Challenge Journal of Concrete Research Letters
https://challengejournal.com/index.php/cjcrl
<a href="https://cjcrl.challengejournal.com"><img src="/public/journals/6/images/CJCRL_small.png" alt="" width="200" height="181" align="left" hspace="10" /></a><p><em style="font-style: normal;"> <a href="https://cjcrl.challengejournal.com"><strong>cjcrl.challengejournal.com</strong></a></em></p><p><em>Challenge Journal of Concrete Research Letters</em> is an international, quarterly published and open access scholarly journal that publishes original research articles as well as short communications, review articles, case studies, discussions, book reviews and letters to the editor in all areas of concrete research.</p><p><em>Challenge Journal of Concrete Research Letters </em>(<em>CJCRL</em>) -formerly known as <em>Concrete Research Letters</em>- publishes as rapidly as possible manuscripts of high quality which addresses eminent topics related to concrete performance, production, durability, sustainability and applications. Being an international, peer-reviewed, online and open-access journal, <em>CJCRL</em> presents a world-wide forum for the dissemination of knowledge among engineers, scientists and mathematicians working in the field of concrete.</p>Tulpar Academic Publishingen-USChallenge Journal of Concrete Research Letters2548-0928Cover & Contents Vol.15 No.1
https://challengejournal.com/index.php/cjcrl/article/view/782
Journal Management CJCRL
Copyright (c) 2024 Tulpar Academic Publishing
2024-03-092024-03-09151The effect of the gravity on the earthquake performance of roller compacted concrete dams
https://challengejournal.com/index.php/cjcrl/article/view/755
<div><p class="CJ-Abstracttext">Roller compacted concrete (RCC) is a dry concrete mixture often utilized in the construction of large dams. The interlayer of the RCC dam, which is the weakest plane of the structure, can easily fail under hydraulic shear load, geological impact, earthquake force and environmental impact. In this study linear and performance analyzes were carried out for eight different scenarios for foundation effect, gravity effect and empty and full reservoir situations. In analyses, the earthquake response and performance of the Akçakoca RCC Dam, taking into account the interaction between the dam and the water. The reservoir water behavior is simulated using the Eulerian-Lagrangian coupled (CEL) approach with finite elements modeling. Linear analyses reveal that hydrodynamic pressure leads to increased displacements and principal stresses. The earthquake performance evaluation of the Akçakoca RCC dam indicates that critical concrete damages are expected based on linear time-history analyses conducted for both empty and full reservoir scenarios. Besides, according to this study, gravity effect clearly increases the earthquake performance of the dam.</p></div>Fethi ŞermetMurat Emre KartalMuhammet Ensar YiğitEmin Hökelekli
Copyright (c) 2024 by the Authors. This is an open access article distributed under the CC BY licence.
2024-03-092024-03-09151202910.20528/cjcrl.2024.01.003Advantageous approach for boron ores used in cement production: optimization of dehydration
https://challengejournal.com/index.php/cjcrl/article/view/753
<div><p class="CJ-Abstracttext">Boron with a certain water content is used for industrial purposes, including cement production. It is necessary to perform and optimize heat treatments and determine the water content. The heat treatment is applied to boron ores that must be used for cement production. However, these processes take time and increase costs. With this study, it will be possible to obtain boron products with the desired properties in a shorter time by determining the optimal parameters for dewatering processes. Colemanite and ulexite ores were reduced to a grain size of 44 microns by ore dressing processes and subjected to dewatering. The Taguchi method was used to optimize the dehydration of colemanite and ulexite ores. The orthogonal design of experiments method L<sub>18</sub>(6<sup>1</sup>3<sup>2</sup>) 3 factors, 18 trials was chosen to determine the design of experiments. The changes in the H<sub>2</sub>O-CaO-Na<sub>2</sub>O-B<sub>2</sub>O<sub>3</sub> concentrations were determined on the basis of the analyses performed. TG/DTA analyses were carried out for comparison with the dehydration processes. In the optimization processes performed using the Taguchi method, the maximum water removal was achieved with 1 g of ore and a period of 6 hours. H<sub>2</sub>O removal was 98.42% at 650 °C for colemanite and 99.1% at 300 °C for ulexite. It has been shown that the dehydration of ulexite and colemanite ores can be optimized and the boron product with the desired properties can be obtained in a short time, which is an advantage for its use in the cement industry. It is expected that this study will serve as an important basis for future applications of B<sub>2</sub>O<sub>3</sub> cement.</p></div>Mustafa Engin KocadağistanHarun Arslan
Copyright (c) 2024 by the Authors. This is an open access article distributed under the CC BY licence.
2024-03-092024-03-0915171910.20528/cjcrl.2024.01.002Reinforcement of concrete beams using waste carbon-nanoclay-fiberglass laminate pieces
https://challengejournal.com/index.php/cjcrl/article/view/713
<div><p class="CJ-Abstracttext">In the last few decades, strengthening of structures in need of repair with fiber reinforced polymer (FRP) composite materials produced with different fiber types has gained great importance. Within the scope of this experimental study, the usability of hybrid glass and carbon composite laminates produced for different purposes and later cut into waste was investigated for concrete reinforcement. Hybrid composite laminates were produced in the form of glass-carbon-glass and carbon-glass-carbon, and the effect was investigated in two different sequences in the study. In addition, there are 3 different rates of nanoclay (0.50%, 0.75% and 1.25%) in the production of composite materials, and the effect of nanoclay ratio was investigated. In the study, two different numbers of composite laminates were adhered to the concrete samples produced in 70x70x280 mm dimensions and subjected to flexural strength test. In the Carbon-Glass-Carbon series using triple waste laminate pieces, the highest flexural strength was reported in the CGC-0.75-3 series, which achieved an increase of approximately 55% and 42% compared to the Control and Control-E series. It was determined that the effectiveness of the reinforcement technique of concrete with laminates in flexure did not change significantly depending on the number of laminate pieces. The main mode of failure in the experimental work was due to concrete fracture.</p></div>Zinnur ÇelikEmrah TuranMeral OltuluGülşah Öner
Copyright (c) 2024 by the Authors. This is an open access article distributed under the CC BY licence.
2024-03-092024-03-091511610.20528/cjcrl.2024.01.001An overview on the hazards and handling methods of construction and demolition wastes: Special focus on recycled concrete aggregates
https://challengejournal.com/index.php/cjcrl/article/view/738
<div><p class="CJ-Abstracttext">With the demand increased in construction activities within the last century, several scientific research studies have been focusing on different aspects of construction and demolishing wastes, while considering the severity of environmental problems that they cause. This work presents the results of out an extensive literature survey in order to provide an overview on the hazards and handling methods of construction and demolishing wastes. Results of this literature review indicate that landfilling has been the most commonly used method, even though the recycling of the construction and demolishing wastes was found out to be the most environmentally-friendly solution. It was observed that groundwater and soil may be heavily affected by the leaching constituents of landfilled construction wastes. On the other hand, using these wastes in the form of recycled concrete aggregates was observed to eliminate these hazards. The results of literature survey pointed out that the use of demolished concrete wastes as recycled concrete aggregates could be widely adopted by construction sector only if the resulting concrete is of satisfactory quality. Hence, information on different quality aspects of concrete made of recycled concrete aggregates are presented systematically as a clear guide in this work, to verify its feasibility as an environment-friendly waste elimination method.</p></div>Alhamza DerkiPınar Akpınar
Copyright (c) 2023 by the Authors. This is an open access article distributed under the CC BY licence.
2023-12-182023-12-1815111812710.20528/cjcrl.2023.04.003Effect of hemp and basalt fiber on fracture energy of cement-based composites: a comparative study
https://challengejournal.com/index.php/cjcrl/article/view/736
<div><p class="CJ-Abstracttext">Fiber-reinforced composites are one of the most used construction materials. Nowadays, some types of fibers like steel, carbon, glass and basalt are commonly used in these composites. However, the production of these fibers consumes natural resources and a high amount of energy. Researchers have started working on natural fibers to reduce commonly used fibers productions’ drawbacks for more sustainable composites. However, the effect of natural fibers on the properties of cement-based composites -especially fracture energy- still needs further research and comparing with the behavior of commonly used fibers. In this study the effect of hemp fiber on the mechanical properties and fracture energy of cement-based fiber-reinforced mortar mixtures was investigated. The results were compared with those of the basalt fiber-reinforced mixtures. The results showed that the flexural strength and fracture energy improved with the use of hemp and basalt fiber compared to the fiber-free mixture. The flexural strength increased up to 10.7% and 19.6% with the inclusion of hemp and basalt fibers, respectively. The mean peak load and fracture energy of hemp fiber-reinforced mortar was higher than those of the fiber-free mixture by 32.2% and 17.9%, respectively. The corresponding values for basalt fiber addition 60.8% and 146.4%.</p></div>Adil Gultekin
Copyright (c) 2023 by the Authors. This is an open access article distributed under the CC BY licence.
2023-12-182023-12-1815110711710.20528/cjcrl.2023.04.002Cover & Contents Vol.14 No.4
https://challengejournal.com/index.php/cjcrl/article/view/699
Journal Management CJCRL
Copyright (c) 2023 by the Authors. This is an open access article distributed under the CC BY licence.
2023-12-182023-12-18151Optimization of reinforced concrete beam using hybrid algorithms with multi-objective function as CO2 emission and cost
https://challengejournal.com/index.php/cjcrl/article/view/726
<div><p class="CJ-Abstracttext">In this study, algorithms with two objective functions are defined considering the TS500 (2000) (Reinforced concrete structures design and construction rules) and TBDY (2018) (Turkey Building Earthquake Regulation) standards for rectangular beam design. These objective functions were determined as CO<sub>2</sub> emission and cost. Optimizations were performed in MATLAB program using the Hybrid Algorithm of Teaching-Learning Based Optimization and Jaya Algorithm. In the case of using two objective functions, cases were created by multiplying the coefficient values found in the objective function according to the formula with the cost and CO<sub>2</sub> emission values at different rates in order to prevent CO<sub>2</sub> emission which is one of the biggest problems for the world. In the objective function, each rate used for CO<sub>2</sub> and cost is implemented in a manner that increases or diminishes the impact of these values. In this way, comparisons were made between the cross-section dimensions to be formed according to not only impact rates but also the reinforcement area to be used, the CO<sub>2</sub> emission and cost values that will arise as a result of these. Impact rates are related to cost and CO<sub>2</sub> rate in the objective function, and the total rate is chosen as 1. Impact rates for cost are chosen as 0.1, 0.3 along with 0.5, and comparisons between the results are checked. In addition, recyclable and non-recyclable steel with different properties were used in separate analyses and the values were compared. Since the CO<sub>2</sub> rate released by the non-recyclable steel is very high compared to the recyclable steel, the results show that the CO<sub>2</sub> emission value is higher and this causes the objective function value to increase.</p></div>Muhammed ÇoşutGebrail BekdaşSinan Melih Nigdeli
Copyright (c) 2023 by the Authors. This is an open access article distributed under the CC BY licence.
2023-12-182023-12-181519610610.20528/cjcrl.2023.04.001Evaluation of the lightweight foamed concrete characteristics
https://challengejournal.com/index.php/cjcrl/article/view/702
<div><div><p class="CJ-Abstracttext">The purpose of this paper is to assess the properties of light weight foamed concrete. In this research, two phases are investigated. The first stage explored the characteristics of fresh and hardened foamed concrete using a foaming agent. The following parameters were employed in this study: foaming agent used as a volume of concrete mix by 10, 20, and 40%, fly ash used as a replacement of cement content by 10, 25, and 50%, and polypropylene fiber used with varied volume fractions of 0.5, 0.75, and 1.0%. Slump values are applied to evaluate the fresh properties. To evaluate the hardened concrete, the dry density and compressive strength at 7 and 28 days are computed. Furthermore, the 28-day tensile splitting strength and flexural strength are studied. The effect of a high temperature was evaluated. The second stage investigated the effects of polypropylene fiber on both fresh and hardened concrete. It was observed that foaming agents improve fresh characteristics while decreasing compressive strengths and dry density. Furthermore, utilizing fly ash improves the characteristics of both fresh and hardened foamed concrete. The fiber reduces the fresh characteristics while enhancing the toughened properties. Because of its low density, foamed concrete is being used for structural applications because of this study. Such as those utilized for thermal insulation, acoustic impedance, and fire breaks. Also used to create road foundations for roads built on soft soil.</p></div></div>Zeinab A. EtmanSamar A. Rokbah
Copyright (c) 2023 by the Authors. This is an open access article distributed under the CC BY licence.
2023-09-152023-09-15151596810.20528/cjcrl.2023.03.001Performance of light weight ferrocement composite walls
https://challengejournal.com/index.php/cjcrl/article/view/712
<div><p class="CJ-Abstracttext">The aim of this research is to examine the performance of reinforced lightweight ferrocement walls under vertical and horizontal loading. The walls were made up of two thin layers of ferrocement reinforced with one, two, three, or four layers of welded wire mesh or expanded steel mesh. The panels’ core was constructed of lightweight extruded foam. An experimental program of thirteen lightweight walls with total dimensions of 100x650x1250 mm was casted to achieve this goal and tested until failure. ABAQUS finite-element package was conducted. The parameters in this study were the kind of reinforcement; welded and expanded wire meshes, the steel bars, and. the number of layers of steel mesh. Ultimate load, mode of failure, initial cracking load, service load, energy absorption, and ductility ratio were calculated and observation to evaluate the findings. The findings displayed that the performance of the ferrocement walls reinforced with expanded wire meshes is better than that of the walls reinforced with welded wire meshes. The energy absorbed increased by 40 % for specimens reinforced with expanded wire meshes is more than that of the walls reinforced with welded wire a good agreement was observed among the theoretical and experimental observations. This paper highlights uses of employing light weight ferrocement units in building of economic housing, which is particularly valuable for both developed and developing nations, with significant frugal benefits.</p></div>Yousry Bauomy I. ShaheenZeinab Abd El khaleq EtmanDoha Elmetwally Abdelmonem Kandil
Copyright (c) 2023 by the Authors. This is an open access article distributed under the CC BY licence.
2023-09-152023-09-15151698810.20528/cjcrl.2023.03.002Mechanical, durability and solar reflectance properties of colored self‒compacting concrete
https://challengejournal.com/index.php/cjcrl/article/view/716
<div><p class="CJ-Abstracttext">Urbanized areas are known to have significantly higher temperatures than rural areas. The Urban Heat Island (UHI) effect is caused by surfaces such as asphalt, buildings, and other heat-absorbing surfaces that store more heat than natural vegetation. Sunlight reflecting properties of building materials are improved with different applications. The present study investigates the mechanical, durability and solar reflectance properties of the colored self-compacting concrete. SCCs containing yellow, green, and black pigments were produced and evaluated. The fresh properties were determined with the slump, L-Box and V-funnel tests. Furthermore, compressive strength, solar reflectance and magnesium sulfate resistance tests were conducted. Yellow pigment added SCC showed a great potential (with the albedo of 0.42) in terms of solar reflectance and decreasing the contribution to the urban heat island effect.</p></div>Sadık Alper Yıldızel
Copyright (c) 2023 by the Authors. This is an open access article distributed under the CC BY licence.
2023-09-152023-09-15151899510.20528/cjcrl.2023.03.003Cover & Contents Vol.14 No.3
https://challengejournal.com/index.php/cjcrl/article/view/698
Journal Management CJCRL
Copyright (c) 2023 by the Authors. This is an open access article distributed under the CC BY licence.
2023-09-152023-09-15151Use of crushed bricks and recycled concrete as replacement for fine and coarse aggregates for sustainable concrete production
https://challengejournal.com/index.php/cjcrl/article/view/656
<div><p class="CJ-Abstracttext">The growing concern over the significant ecological changes requires sustainable developments in all fields. Concrete production is one of the largest consumers of natural resources as it consumes a huge volume of natural fine and coarse aggregates, which constitute 70% - 80% of the concrete volume. It is evident that such large amount of concrete production in the growing construction industry puts significant impact on the use of natural resources and the environment. Hence, investigating the use of recycled materials to replace the finite natural resources became evident and is the focus of researchers. In this research, the use of waste crushed bricks (CB), and crushed recycled concrete (CRC) as a partial replacement of fine and coarse aggregates in concrete was studied. The replacement ratios of 10%, 50%, and 100% by weight of either fine or coarse aggregates were used. Eight concrete mixes with 168 specimens were tested for compressive, splitting tensile as well as, flexural strength. All tests were carried out at ages of 7, 28 and 56 days. The results indicated that there is a feasibility of using bricks and concrete wastes in concrete mix as a partial replacement of course and fine aggregates. It is deduced that a 50% replacement ratio of coarse aggregate with crushed concrete resulted in a 30%, 25%, and 23% increase in compressive, tensile, and flexural strengths, respectively. While 50% replacement ratio of fine aggregate with crushed bricks resulted in a 23%, 28%, and 19% increase in compressive, tensile, and flexural strengths, respectively. The most effective mix was at 50% replacement ratio of coarse aggregate with crushed concrete in combination with 50% replacement ratio of fine aggregate with crushed bricks. The results of this mix showed 32%, 28%, 26% increase in compressive, tensile, and flexural strengths, respectively.</p></div>Alaa Abdeltawab AboalellaAbeer Elmalky
Copyright (c) 2023 by the Authors. This is an open access article distributed under the CC BY licence.
2023-06-202023-06-20151394610.20528/cjcrl.2023.02.002Chemical resistance of hardened mortar containing andesite and marble industry waste powder
https://challengejournal.com/index.php/cjcrl/article/view/687
<div><p class="CJ-Abstracttext">The sludge generated during forming processes of marble and andesite rocks is kept in dust form after drying. Due to the high consumption of andesite and marble, the storage and health problems of these dusts arise. Therefore, reducing the environmental impacts of waste and recovering them for the economy is an important issue. For this purpose, in this work, mortar specimens were manufactured using 0%, 5%, 10%, 15% and 20% of waste marble and andesite powders separately by Portland cement. Strength properties of the samples were investigated before and after immersion to the hydrochloric acid (HCl), sodium sulfate (Na<sub>2</sub>SO<sub>4</sub>) and magnesium sulfate (MgSO<sub>4</sub>) solutions. The results indicated that partial substitution of Portland cement by andesite and marble powder up to 10% have positive influence on the mechanical properties of the mortars at ambient conditions. In addition, the andesite incorporated mortars have the better performance under the acid and sulfate environments than the other mortars. On the other hand, substitution of Portland cement by marble powder more than 5% has negative influence on the chemical resistance of the mortars.</p></div>İsmail İsa AtabeySerhat ÇeliktenMehmet Canbaz
Copyright (c) 2023 by the Authors. This is an open access article distributed under the CC BY licence.
2023-06-202023-06-20151313810.20528/cjcrl.2023.02.001Efficacies of suggested strength-based prediction models for estimation of compressive and tensile properties of normal concrete
https://challengejournal.com/index.php/cjcrl/article/view/701
<div><p class="CJ-Abstracttext">One of the most crucial challenges faced by today’s construction industry for a speedy delivery is undeniably the ‘time-factor’ accompanied by promised quality within the framework of distinct budget. Strength based - Prediction models helps in estimating the early strengths as well as later-stage strength or strength at any age of concrete. Such models assist the structural and execution engineers in arriving at a fair judgement of compressive strength of concrete. A normal practice usually followed by the material testing laboratories and quality assurance cell at site is to assess the cube compressive strength of concrete which is an intrinsic engineering property governing the design and performance phase of structures. It is found from the literature that most of the prediction models that are formulated to estimate the compressive strength of concrete at any age are actually based on cylinder compressive strength of concrete. Therefore, this paper attempts to use some of the suggested prediction models with two sets of data, that is, one by considering experimental results of cube compressive strength found at the age of 7, 14 and 28-days and two by utilizing a conversion value, suitable cylinder compressive strength is obtained. These datasets are thoroughly used in the prediction models to accurately estimate the compressive strength of concrete. Similarly, appropriate prediction models are sought to determine the split tensile strength of normal concretes based on cubic compressive strength and cylinder compressive strength. Particularly, results of the present study showcase that although the prediction models are developed based on cylinder compressive strength, they can agreeably be used on cube strength data as the ratio of (Pi/Ai) obtained is the higher range of 0.85-1.00 and with only an early cube strength result, it is possible to predict an accurate value of split tensile strength of concrete at an age of 28-days. The effectiveness of suggested prediction models through statistical parameters are determined and their efficiencies are found to be in the higher range of 94% to 98%.</p></div>Mukunda Matada Nalina
Copyright (c) 2023 by the Authors. This is an open access article distributed under the CC BY licence.
2023-06-202023-06-20151475810.20528/cjcrl.2023.02.003Cover & Contents Vol.14 No.2
https://challengejournal.com/index.php/cjcrl/article/view/697
Journal Management CJCRL
Copyright (c) 2023 by the Authors. This is an open access article distributed under the CC BY licence.
2023-06-202023-06-20151Axial compression behaviour of concrete-filled auxetic tubular short columns
https://challengejournal.com/index.php/cjcrl/article/view/684
<div><p class="CJ-Abstracttext">Concrete-filled steel columns (CFSCs) are of great interest in the literature as they are capable of carrying higher loads by combining the exceptional qualities of steel and concrete. With auxetic materials being introduced to civil engineering applications, the influence of these materials on CFSCs remains a matter of curiosity. The current study implements a nonlinear finite element analysis to evaluate the performance of circular CFSCs with six auxetic tubes under axial compression and the proposed numerical model was validated using published experimental data. The effect of the auxetic steel tube’s porosity and Poisson’s ratio on CFSCs was examined parametrically in terms of ultimate strength using the confined concrete model. Moreover, the stress distributions of the concrete and the auxetic steel tubes were also thoroughly examined. Based on the findings of the analysis, the ultimate load of CFSCs, utilising auxetic tubes with the same density and porosity but different Poisson’s ratio, increased proportionally with the increase of auxetic behaviour. When it comes to auxetic tubes with different densities and porosities, the influence of the Poisson’s ratio of the tubes diminished and the stiffness of tubes became more dominant over the mechanical characteristics of columns as the density of the auxetic steel tubes increased or decreased. The stiffness of the auxetic tubes reduced as porosity increased, as did the ultimate load of the columns. Additionally, the ultimate loads of the auxetic steel tube columns are found to be lower than those of bare steel tube columns filled with concrete due to perforations.</p></div>Kemal SolakSüleyman Nazif Orhan
Copyright (c) 2023 by the Authors. This is an open access article distributed under the CC BY licence.
2023-03-072023-03-071511910.20528/cjcrl.2023.01.001Cause of distress of an old building through analytical and micro‒analytical methods ‒ a case study
https://challengejournal.com/index.php/cjcrl/article/view/534
<div><p class="CJ-Abstracttext">The case study pertains to the methods such as nondestructive, semi-destructive, chemical, electrochemical and micro-analytical, utilized to assess the cause of cracking and spallation of a reinforced concrete building near to the eastern coastline of India. Cause of degradation of the structure is assessed to arrive at the appropriate repair methodology. From the analysis methods, direct cause of failure could not be attributed to a single cause since many factors co-exist such as structural cracking, carbonation and presence of chloride and the synergistic effect; hence concludes that an appropriate repair methodology has to be evolved to address each issue.</p></div>Rajappan PreethaKalpana KumariBalakrishnan SakthiChandrasekharan Nair HarikumarHaneef Ibrahim Abdul Gani
Copyright (c) 2023 by the Authors. This is an open access article distributed under the CC BY licence.
2023-03-072023-03-07151183010.20528/cjcrl.2023.01.003Optimization of reinforced concrete frame structures and matrix displacement method
https://challengejournal.com/index.php/cjcrl/article/view/688
<div><div><p class="CJ-Abstracttext">In this study, reinforced concrete frame system is generated, and all structural elements which are beam and columns are optimized according to the applied distributed loads and different concrete classes by using Matlab program. Jaya algorithm which is a Metaheuristic Algorithm that enables to optimization process and finds the best cross sections, reinforcement area as well as cost of the system, is proposed. It is observed that cross-section, reinforced area as well as cost of the system are changed when concrete classes are used differently. After finding the optimum design values for frame system, the matrix displacement method is utilized to specify the system displacements and all nodes forces. Furthermore, columns and beam displacement results are not similar, and also internal forces are different for nodes. TS500 (2000) (Reinforced concrete structures design and construction rules) and TBDY (2018) (Turkey Building Earthquake Regulation) are used together to specify variables, constraints and also necessity values. The proposed method is feasible for frame structures consisting of different members.</p></div></div>Muhammed ÇoşutGebrail BekdaşSinan Melih Nigdeli
Copyright (c) 2023 by the Authors. This is an open access article distributed under the CC BY licence.
2023-03-072023-03-07151101710.20528/cjcrl.2023.01.002Cover & Contents Vol.14 No.1
https://challengejournal.com/index.php/cjcrl/article/view/696
Journal Management CJCRL
Copyright (c) 2023 by the Authors. This is an open access article distributed under the CC BY licence.
2023-03-072023-03-07151Cover & Contents Vol.13 No.4
https://challengejournal.com/index.php/cjcrl/article/view/630
Journal Management CJCRL
Copyright (c) 2022 by the Authors. This is an open access article distributed under the CC BY licence.
2022-12-132022-12-13151Effect of steam‒curing on the glass fiber reinforced concrete
https://challengejournal.com/index.php/cjcrl/article/view/662
<div><p class="CJ-Abstracttext">Due to the increased need to use precast concrete to reduce construction duration and to accelerate the cement reaction process to achieve the required concrete resistance that enables the elements to gain the required strength to handle the loads generated by the transportation process, many companies use steam curing methods to expedite the hydration process. The steam curing process negatively affects the concrete strength, especially in the long term. Fibers of different types are used to improve the interior composition of concrete and increase its crack resistance. The purpose of the current study was to determine the effect of the glass fiber on the behavior of steam-cured concrete. In this study 90 concrete cubes were used with 15cm dimensions, three different weight ratios of glass fibers (0%, 0.12%, and 0.24%) with two curing methods standard curing in the water tank (water curing - WC) for 3, 7, and 28 days, and steam curing (SC) for 4 and 8 hours. Nine specimens of each mix were cast in 12 mm, and 24 mm fibers length and tested for each curing duration and method. The results of this study indicate that fiber glass addition to the steam-cured concrete has a positive effect on the concrete unit weight and the ultrasonic pulse velocity. Moreover, the result showed that the tensile and compressive strength of the concrete has been positively affected by the length of the fiber more than the fiber weight percentage.</p></div>Mehmet CanbazMouad BensaoudHakan ErolHasan Selim Şengel
Copyright (c) 2022 by the Authors. This is an open access article distributed under the CC BY licence.
2022-12-132022-12-1315110711510.20528/cjcrl.2022.04.001Economical evaluation of reinforced concrete hospital construction cost using bottom ash and fly ash
https://challengejournal.com/index.php/cjcrl/article/view/670
<div><p class="CJ-Abstracttext">The use of waste materials in nature (e.g. fly ash, bottom ash) in the construction phase of buildings is of great importance both in terms of environmental pollution and the construction cost of the structures. Therefore, in this study, the effects of bottom ash and fly ash on the construction cost of reinforced concrete (RC) hospital buildings are investigated by considering experimental tests and 3D nonlinear analyzes. During the experiments, four different concrete series are created and fly ash and bottom ash are added to replace 0–5 mm grain size aggregates in the concrete mixture at different ratios. The RC beams created according to four different concrete series are subjected to experimental tests. Afterward, it is determined that the most critical mixing ratio for RC beams subjected to experimental tests is selected as 75% bottom ash ratio and fly ash. For the purpose Ankara Bilkent City Hospital is selected for 3D nonlinear seismic analyses and the hospital structure is subjected to 10 various earthquake analyses. This study showed that there was a noticeable decrease in the construction cost when the costs of the hospital structure were compared as a result of the earthquake analysis. Another important point is that the use of bottom ash and fly ash is thought to contribute to savings in the energy to be used for the storage of wastes by causing less electrical energy use in cement production, less greenhouse gas emissions, natural raw material consumption and nature pollution.</p></div>Burak OzMemduh KaralarMurat Çavuşli
Copyright (c) 2022 by the Authors. This is an open access article distributed under the CC BY licence.
2022-12-132022-12-1315111612610.20528/cjcrl.2022.04.002Effects of fibers geometry and strength on the mechanical behavior and permeability properties of slurry infiltrated fiber concrete (SIFCON)
https://challengejournal.com/index.php/cjcrl/article/view/673
<div><div><p class="CJ-Abstracttext">The use of slurry-infiltrated fiber concrete (SIFCON) has been increasing in recent years. SIFCON is a very good alternative, especially in structural reinforcement processes. In this study, the effects of 2 different steel fibers of normal strength (3D) and high strength (5D) with different geometry and strength properties and polyolefin origin synthetic fiber are examined on the mechanical behavior and capillary water permeability properties of SIFCON. Steel fibers were used in 2 different ratios by volume 4% and 8%, while polyolefin synthetic fiber was used at 4% by volume. The bending strength and splitting tensile strength of SIFCON containing 5D steel fiber are 46.47 MPa and 18.47 MPa, respectively, 4.9 and 2.1 times higher than plain concrete. In addition, the fracture energy of SIFCON containing 5D steel fiber is 20400 N/m, and it is 358 times higher than plain concrete, 1.6 and 3.1 times higher than concrete containing the same amount of 3D fiber and polyolefin synthetic fiber, respectively. The capillary water absorption of SIFCON, which contains 4% synthetic fiber and 8% 3D steel fiber by volume, is 0.121 mm and 0.112 mm, respectively, which is higher than all other mixtures in the study. As a result of the study, higher splitting tensile strength, bending strength and fracture energy values were obtained in concretes containing 5D steel fiber, which have high tensile strength and have better adhesion to concrete due to its geometry. The use of synthetic fibers or high amounts of steel fibers increased the permeability.</p></div><p> </p></div>Fatih Özalp
Copyright (c) 2022 by the Authors. This is an open access article distributed under the CC BY licence.
2022-12-132022-12-1315112713610.20528/cjcrl.2022.04.003Cover & Contents Vol.13 No.3
https://challengejournal.com/index.php/cjcrl/article/view/629
Journal Management CJCRL
Copyright (c) 2022 by the Authors. This is an open access article distributed under the CC BY licence.
2022-09-292022-09-29151Assessing effects of waste coal bottom ash on construction cost of reinforced concrete structures considering experimental data
https://challengejournal.com/index.php/cjcrl/article/view/641
<div><p class="CJ-Abstracttext">In this study, it has been examined whether the bottom ash (BA) released to the nature as waste material from the thermal power plant can be used in reinforced concrete structures (RCS) and how much cost reduction will be caused in construction technology if BA is used in RCS. For this purpose, coal BA produced by Turkey-Zonguldak Cates power plant is mixed in different ratios into the concrete mixture of the beams. The different coal bottom ash ratio (BAR) is used instead of aggregate in the mixture. The beams created for 5 different BARs are subjected to tests and it is observed that the beam with the most critical bending is the beam with 75% coal BA. This BAR is applied to bearing elements of finite element model (FEM) and then current cost of the building and the construction cost used 75% coal BAR are compared with each other. It has been observed that when 75% coal BAR is used instead of aggregate in RCSs, there is a 40% reduction in construction costs. This result is of great importance both for the recycling of BA and for revealing that BA reduces construction costs.</p></div>Memduh KaralarBurak ÖzMurat Çavuşli
Copyright (c) 2022 by the Authors. This is an open access article distributed under the CC BY licence.
2022-09-292022-09-29151809210.20528/cjcrl.2022.03.001Mechanical behavior investigation of rubberized concrete barriers in impact load
https://challengejournal.com/index.php/cjcrl/article/view/650
<div><p class="CJ-Abstracttext">Approximately 1.5 million waste tires are produced annually. Waste tires in landfills and stocks cause toxic chemicals to pollute the soil and cause major fires. Waste tires are a global environmental problem. This problem gave an idea of recycling of waste tires instead of landfills and stocks. In this paper, an experimental study is conducted to review the behavior under impact load of rubberized concrete with conventional concrete. Three different mixes were made by adding crumb rubber (0%, 5% and 10%) by volume to the concrete. Nine cantilever column specimens of three type cross section (10x10, 15x15 and 20x20 cm2) were used to investigate the behavior under impact load. The specimens with higher rubberized concrete have longer impact load duration at the initial peak point. Specimens with rubber content become much flexible than normal specimens. Furthermore,<strong> </strong>the damage level of columns is greater with increasing rubber content. Therefore, the specimens with higher rubberized concrete absorb more impact energy. The barriers with higher rubber content minimize injury and demise when an accidental impact happens. Using concrete with rubber content reduces costs and produces an environmentally sustainable solution.</p></div>Hasan Selim ŞengelAhmet Şahin ÖzgörenHakan ErolMehmet Canbaz
Copyright (c) 2022 by the Authors. This is an open access article distributed under the CC BY licence.
2022-09-292022-09-291519310010.20528/cjcrl.2022.03.002Effect of waste concrete powder on slag-based sustainable geopolymer composite mortars
https://challengejournal.com/index.php/cjcrl/article/view/668
<div><p class="CJ-Abstracttext">In this study, the effect of waste concrete powder (WCP) on slag-based geopolymer composite mortars was investigated. Blast furnace slag (BFS) and WCP were used as binders in geopolymer mortars. WCP was substituted into the geopolymer mortar composites at rates of 10%, 20%, 30%, and 40% by weight of slag. Sodium hydroxide (NaOH) solution was used as the alkali activator in the mixtures and the solution activator concentration was chosen as 16 molars (M). After the prepared mortars were cured at 100°C for 24 hours, they were subjected to flexural strength (<em>f<sub>fs</sub></em>), compressive strength (<em>f<sub>cs</sub></em>), and ultrasonic pulse velocity (UPV) tests. When the obtained results were examined, it was observed that <em>f<sub>fs</sub></em>, <em>f<sub>cs,</sub></em> and UPV results decreased with the increase in WCP replacement ratio. These decrements were seen clearly, especially after the 20% replacement ratio. However, despite these decrements, the compressive strengths of all groups were found to be above 50 MPa. In addition, it is thought that environmental pollution can be reduced by using WCP in geopolymer composite mortars.</p></div>Erdinç Halis AlakaraÖzer Sevimİlhami DemirGazi Günel
Copyright (c) 2022 by the Authors. This is an open access article distributed under the CC BY licence.
2022-09-292022-09-2915110110610.20528/cjcrl.2022.03.003Minimum weight design of reinforced concrete beams utilizing grey wolf and backtracking search optimization algorithms
https://challengejournal.com/index.php/cjcrl/article/view/647
<div><p class="CJ-Abstracttext">In this study, optimal weight design of a reinforced concrete beam subjected to various loading conditions is investigated. The purpose of the optimization is to attain the minimum weight design of the reinforced concrete beam under distributed and two-point loads. The design problem is handled under three different design load cases. The two-point loads are affected on beam-to-beam connection nodes of reinforced concrete beams. Thus, while the magnitudes of distributed load and two-points load are remained constant, the distances between two-points loads are taken as 2m, 3m and 4m, respectively. The width and height of the rectangular cross-section of the concrete beam, and the diameters of the longitudinal and confinement steel rebars are treated as design variables of the optimum design problem. The design constraints of the optimization problem consist of the geometric constraints and necessities of the Turkish Requirements for Design and Construction of Reinforced Concrete Structures (TS500), and Turkish Building Earthquake Code (TBEC). As two novel metaheuristics, grey wolf (GW) and backtracking search (BS) optimization algorithms are selected as optimizers. Both algorithms are independently operated five times for three different design problems. Thus, the obtained results are examined statistically to compare in accordance with algorithmic performances. The optimal findings from optimization algorithms show that the GW algorithm is a little bit more robust on the exploitation phase, while the BS algorithm is stronger on the exploration phase. Moreover, it can be deducted from optimal beam designs that the GW algorithm is more viable to minimize reinforced concrete beam design.</p></div>Osman TuncaSerdar Çarbaş
Copyright (c) 2022 by the Authors. This is an open access article distributed under the CC BY licence.
2022-06-062022-06-06151727910.20528/cjcrl.2022.02.003Research on micro limestone for concrete pavements produced with natural aggregates in the Erzurum region
https://challengejournal.com/index.php/cjcrl/article/view/640
<div><p class="CJ-Abstracttext">The use of naturally formed aggregates in concrete pavements is an innovative and sustainable solution both environmentally and economically. This study investigates the usability of fine and coarse aggregates formed spontaneously in Oltu, Narman, Pasinler and Uzundere in concrete pavements by improving the mechanical properties of concrete. In the study, the compressive strength, flexural strength, water absorption capacity and capillarity permeability of the concrete samples planned to be used on concrete pavements were obtained by considering the contribution of these aggregates. In addition, microscopic electron scanning analyzes (SEM) were applied to visualize the internal cracks that may occur in the concrete. The test results showed that the concrete formed with aggregates from Oltu and Pasinler regions had the highest compressive, flexural and hardened unit weights. It has been concluded that the concrete produced from Uzundere region, which gives results below 35 MPa in terms of compressive strength, is not applicable on concrete pavements. In addition, considering the high compressive, flexural, unit weight and capillary permeability, it is predicted that the most suitable concrete design for the construction of concrete pavements is the P<sub>0</sub> (concrete formed with aggregates from Pasinler region) concrete sample.</p></div>Ali Öz
Copyright (c) 2022 by the Authors. This is an open access article distributed under the CC BY licence.
2022-06-062022-06-06151627110.20528/cjcrl.2022.02.002Cover & Contents Vol.13 No.2
https://challengejournal.com/index.php/cjcrl/article/view/628
Journal Management CJCRL
Copyright (c) 2022 by the Authors. This is an open access article distributed under the CC BY licence.
2022-06-062022-06-06151Effect of curing time on polymer concrete strength
https://challengejournal.com/index.php/cjcrl/article/view/625
<div><p class="CJ-Abstracttext">With the advancement of polymer technology, polymer concrete (PC) has become increasingly popular throughout the world and it has among the major construction materials due to its many advantages. The strength and durability of PCs are directly related to paste quality and curing time. The curing time is of the utmost importance to ensure desirable mechanical properties. An understanding of the strength-time relationship of PCs is crucial to understanding the effects of loading on concrete at an older age. The objective of this paper is to study the behavior of PC under different curing times with an emphasis on compressive and flexural strengths. Therefore, a total of 63 specimens were tested at seven different ages (1 day, 3 days, 5 days, 7 days, 14 days, 28 days, and 105 days) throughout the study. According to the results obtained from the tests, it is shown that the curing time plays a critical role in the flexural and compressive strengths of PCs. PCs gain more than 80% of their mechanical strength within three days, and the long-term strength does not change significantly after seven days.</p></div>Ferit Cakir
Copyright (c) 2022 by the Authors. This is an open access article distributed under the CC BY licence.
2022-06-062022-06-06151546110.20528/cjcrl.2022.02.001Optimization of axial load carrying capacity of CFST stub columns
https://challengejournal.com/index.php/cjcrl/article/view/604
<div><p class="CJ-Abstracttext">Concrete filled steel tubular (CFST) columns are widely used due to their enhanced mechanical properties. The interaction between the concrete core and the steel casing increases structural stability and magnifies the compressive strength of concrete. Besides the structural performance, in alignment with the commitment of the concrete industry to reduce its environmental impact, lowering the carbon emissions caused by the production of concrete structures is gaining importance in recent years. The current paper gives an overview of the equations available in the literature that predict the axial load carrying capacity of rectangular CFST columns. A modified version of the Jaya metaheuristic algorithm is being proposed and the outcome of this algorithm is being presented. The algorithm is used in order to maximize the axial load-carrying capacity of a stub column. As an optimization constraint the CO<sub>2</sub> emission associated with the production of the CFST column is being kept below a predefined level throughout the optimization process. The optimization process as well as the cross-sectional dimensions associated with the optimum solution are presented.</p></div>Celal ÇakıroğluGebrail Bekdaş
Copyright (c) 2022 by the Authors. This is an open access article distributed under the CC BY licence.
2022-03-242022-03-241511410.20528/cjcrl.2022.01.001Structural behavior of ferrocement composite hollow-cored panels for roof construction
https://challengejournal.com/index.php/cjcrl/article/view/589
<div><p class="CJ-Abstracttext">The main objective of the following work is to study the effect of using different types of metallic and non-metallic mesh reinforcement materials on the flexural behavior of ferrocement hollow-cored panels as a viable alternative for conventional reinforced concrete roofs. The proposed panels are lighter in weight relative to the conventional reinforced concrete panels. Three types of the steel meshes were used to reinforce the ferrocement skin layers. Namely: welded wire mesh, expanded metal mesh, and tenax mesh with various numbers of layers. Experimental investigation was conducted on the proposed panels. A total of ten slabs having the total dimensions of 2000 mm length, 500 mm width and 120 mm thickness were cast and tested under flexural loadings until failure. The deformation characteristics and cracking behavior were recorded and observed for each panel at all stages of loadings. The results showed that high ultimate and serviceability loads, crack resistance control, high ductility, and good energy absorption properties could be achieved by using the proposed panels. This could be of true construction merits for both developed and developing countries alike. The experimental results were then compared to analytical models using (ABAQUS/Explicit) programs. The finite element (FE) simulations achieved better results in comparison with the experimental results.</p></div>Yousry B. I. ShaheenZeinab A. EtmanAya M. Elrefy
Copyright (c) 2022 by the Authors. This is an open access article distributed under the CC BY licence.
2022-03-242022-03-2415152710.20528/cjcrl.2022.01.002Effect of expanded polystyrene beads on the properties of foam concrete containing polypropylene fiber
https://challengejournal.com/index.php/cjcrl/article/view/609
<div><p class="CJ-Abstracttext">In this study, foam concrete was produced using 3 different volumes of EPS beads (up to 100%), 3 different volumes of polypropylene(PP) fiber (up to 0.1)%, sand and 40% pre-produced foam which is fixed by volume. The water-cement ratio was 0.4 and the sand-cement ratio was chosen as 1. The foam concrete were cast into molds with a size of 100 x 100 x 500 mm and 150 x 150 x 150 mm prism. Unit weight, ultrasonic pulse, water absorption, splitting tensile strength, bending strength and compressive strength tests were achieved. Foam concrete were kept in laboratory standard conditions. According to the results of study, unit weight and ultrasonic pulse velocity vary between 970-1350 kg/m<sup>3</sup> and 1.6-2.6 km/sec, respectively. The water absorption of the foam concrete decreased up to 65% as the EPS beads ratio increased. Since EPS beads do not contribute to the strength and act like a void, splitting tensile strength in specimens containing EPS beads decreased by up to 70%. The use of fiber contributes to the splitting tensile strength, especially in specimens that do not contain EPS beads, and it increased the strength by 78%. Similarly, the flexural strength of the PP fiber addition increased by up to 70%. As the EPS beads ratio increased, the flexural strengths decreased by 77%. With the addition of PP fiber, the compressive strength increased by 55%. However, since EPS beads' strength is negligible, it caused a 60% decrease in compressive strength.</p></div>Mehmet CanbazAli Can Türeyen
Copyright (c) 2022 by the Authors. This is an open access article distributed under the CC BY licence.
2022-03-242022-03-24151283510.20528/cjcrl.2022.01.003Effect and optimization of incorporation of nano-SiO2 into cement-based materials – a review
https://challengejournal.com/index.php/cjcrl/article/view/606
<div><p class="CJ-Abstracttext">Incorporation of nanomaterials into cement-based materials has great potentials to improve their performance to great levels and to produce construction materials with superior and unique properties. Various nanoparticles have been utilized in cementitious composites to improve their properties. This paper provides a detailed review about the effect of the most widely incorporated nanomaterial into cement-based materials, namely nano-silica, on different on properties of cement-based materials. The investigated properties are mechanical properties (compressive strength, split tensile strength and flexural strength), durability parameters (permeability, freeze and thaw resistance, high temperature resistance, fire resistance and sulfate attack resistance) and microstructural properties of mortar and concrete. The cost effectiveness of use of nano-silica in cement-based materials is also discussed. The optimum replacement percentage of cement with this nanomaterial to improve the performance of mortar and concrete is also investigated. The investigation showed that nano-silica has the ability to enhance the mechanical properties, durability and microstructural properties of concrete and mortar to a remarkable level. It also showed that the optimum content of nano-silica in concrete and mortar is 1.0-4.0% by weight of binder materials.</p></div>Mohammed Gamal Al-HagriMahmud Sami Döndüren
Copyright (c) 2022 by the Authors. This is an open access article distributed under the CC BY licence.
2022-03-242022-03-24151365310.20528/cjcrl.2022.01.004Cover & Contents Vol.13 No.1
https://challengejournal.com/index.php/cjcrl/article/view/627
Journal Management CJCRL
Copyright (c) 2022 by the Authors. This is an open access article distributed under the CC BY licence.
2022-03-242022-03-24151Predictability of concrete damage level by non-destructive test methods
https://challengejournal.com/index.php/cjcrl/article/view/601
<div><p class="CJ-Abstracttext">Non-destructive methods have many advantages over traditional test methods, especially since it does not damage the specimen, it can be used multiple times on the same specimen. These advantages also provide a great benefit in terms of following the property development in concrete as the same specimens are used which eliminates the variations related to the specimens. In this study, it is aimed to determine the damaged amount of concrete produced with different binders by electrical bulk resistivity, resonance frequency, and ultrasonic pulse velocity methods. Firstly, concretes containing different binders were produced, and along with the mechanical properties, ultrasonic wave velocity, resonance frequency, and electrical resistivity values of the produced concrete were determined at the 7, 28, and 90 days. Besides, the specimens were subjected to gradually increase compressive loads and non-destructive methods were used to estimate the extent of damage on specimens. It was attempted to establish a relationship between the damage on concrete specimens and the results obtained by non-destructive methods. Consequently, the compressive strength, electrical resistivity, ultrasonic pulse velocity and resonance frequency values of all specimens increased with the advancing age. It was concluded that the resonant frequency method is more successful than other methods in estimating the amount of damage in concrete.</p></div>Boğaçhan AkçaSüleyman Bahadır KeskinAysu Göçügenci
Copyright (c) 2021 by the Authors. This is an open access article distributed under the CC BY licence.
2021-12-162021-12-1615113815010.20528/cjcrl.2021.04.004Strength properties of biopolymer treated clay/marble powder mixtures
https://challengejournal.com/index.php/cjcrl/article/view/595
<div><p class="CJ-Abstracttext">Depending on their unique layer structures and chemical structures, soil problems such as swelling, settlement and loss of strength can be seen especially on clay soils when exposed to water. Settlement occurring on clay soils on which the structure is built, causes various damages in the building. Additionally, in the clay soil interacting with water, strength loss occurs due to the effect of the building load. Today, when soil improvement techniques are developed and diversified, clay soils can be stabilized by using different additives. A clay soil that has been improved by adding waste marble powder within the scope of this study in certain percentages (5%, 15%, 25%), biopolymer added clay / marble powder samples were obtained by interacting with locust bean gum in certain percentages (0.5%, 1%, 1.5%). There are many studies in the literature on improving clay soils using only marble powder or only biopolymer. In this study, marble powder and biopolymer were used together and thus, the feasibility of a more effective soil improvement has been investigated. The results showed that the unconfined compressive strength of the biopolymer added clay-marble powder mixtures are higher when compared with natural clay. Similarly, shear box test results showed that the unconsolidated-undrained cohesions and internal friction angles of the doped clay samples increased. It was observed that the strength values of marble powder-added clay increased after improving with biopolymer.</p></div>Zeynep Nese Kurt AlbayrakBanu Altun
Copyright (c) 2021 by the Authors. This is an open access article distributed under the CC BY licence.
2021-12-162021-12-1615113113710.20528/cjcrl.2021.04.003Effects of dry particle coating with nano- and microparticles on early compressive strength of portland cement pastes
https://challengejournal.com/index.php/cjcrl/article/view/600
<div><p class="CJ-Abstracttext">It is known that nano-and microparticles have been very popular in recent years since their advantages. However, due to the very small size of such materials, they have very high tendency to agglomeration particularly for nanoparticles. Therefore, it is critical that they are properly distributed in the system to which they are added. This paper investigated the effects of dry particle coating with nano-and microparticles to solve the agglomeration problem. For a clear evaluation, paste samples were preferred to detemine the compressive strength. Nano-SiO<sub>2</sub> and nano-CaCO<sub>3</sub>, micro-CaCO<sub>3</sub> and micro-SiO<sub>2</sub>, also known as silica fume, were selected as particulate additives. It was studied by the addition of various percentages (0.3, 0.7, 1, 2, 3 and 5%) of nano-and microparticles in cementitious systems, replacing cement by weight with and without dry particle coating. Dry particle coating was made by using a high-speed paddle mixer. Portland cement and additive particles were mixed at 1500 rpm for 30 seconds in high-speed powder mixer designed for this purpose. The 3-day compressive strength of the cement-based samples to which particles were added at the specified rates was determined and the effect of the dry particle coating on the early strength was investigated. According to the results, it was observed that the production of paste with the dry particle coating technique gave higher compressive strength compared to the production of paste directly in early period. Especially with dry particle coating, compressive strength increased more than 100% in paste samples containing 0.3% nano-SiO<sub>2</sub> compared to direct addition without coating.</p></div>Hediye YorulmazSümeyye ÖzuzunBurak UzalSerhan İlkentaparUğur DurakOkan KarahanCengiz Duran Atiş
Copyright (c) 2021 by the Authors. This is an open access article distributed under the CC BY licence.
2021-12-162021-12-1615112513010.20528/cjcrl.2021.04.002Ballistic strength of aerated concrete
https://challengejournal.com/index.php/cjcrl/article/view/588
<div><p class="CJ-Abstracttext">In regional studies conducted by the Law Enforcement Agency and the Armed Forces within the scope of counter-terrorism activities, to ensure peace and security throughout the country and for the police and military personnel to provide security services, the need to produce different solutions has arisen in the face of attacks on the security points established at many important points, especially at the entrance and exit points of the cities. In this context, by changing the direction and angle of the wall types made of aerated concrete used in construction techniques, 7 variations were tested on these wall types with materials formed with adhesive mortar+plaster, monolithic elastomer polyurea, and non-Newtonian fluid, and the strength of these materials were tested with BR6 and BR7 bullets. The main purpose of this study was to determine the most suitable material in terms of security parameters in the shortest time and at a low cost and to create a reliable structure for security cabins. At the end of the study, the best results were obtained with the shots made on the narrow surface of the aerated concrete and the shots made on the platform formed with non-Newtonian fluid.</p></div>Gökhan DurmuşSefa Ekinci
Copyright (c) 2021 by the Authors. This is an open access article distributed under the CC BY licence.
2021-12-162021-12-1615111412410.20528/cjcrl.2021.04.001Cover & Contents Vol.12 No.4
https://challengejournal.com/index.php/cjcrl/article/view/579
CJCRL Journal Management
Copyright (c) 2021 by the Authors. This is an open access article distributed under the CC BY licence.
2021-12-162021-12-16151Cover & Contents Vol.12 No.3
https://challengejournal.com/index.php/cjcrl/article/view/578
CJCRL Journal Management
Copyright (c) 2021 by the Authors. This is an open access article distributed under the CC BY licence.
2021-09-152021-09-15151Predicting and comparing the fire performance of a small-scale composite structure
https://challengejournal.com/index.php/cjcrl/article/view/571
<div><p class="CJ-Abstracttext">The purpose of this paper is to investigate a strategy for the fire testing of reduced scale structural models which will help engineers design safer structures and reduce the loss from fires. The concept of this work is how composite frame floor arrangements, beam-column connections might be modelled at a small scale suitable for fire testing. Testing full-scale is expensive, besides the testing of scaled model produces reasonable results which help us to understand the failure mechanism and all significant thermo-structural responses involved in a fire. Thermal effects within a structural element generate fire curve, thermal input and structural displacement output, in other words cause and impact. Dimensional analysis, which is a condition for dynamic similarity between prototype and model, can be achieved when all the dimensionless groups are set equal for both model and prototype. On the other hand, scaling rules are used to decide how much insulating material will be used on a structure. 5-storey composite building with composite floors and steel columns has been modelled at small scale with 1/5. The obtained results from various parametric investigations show that the reduced scale model fire test method would be a feasible way to investigate the fire performance of composite structures.</p></div>Burak Kaan Cirpici
Copyright (c) 2021 by the Authors. This is an open access article distributed under the CC BY licence.
2021-09-152021-09-15151728710.20528/cjcrl.2021.03.001Mechanical strength variation of zeolite-fly ash geopolymer mortars with different activator concentrations
https://challengejournal.com/index.php/cjcrl/article/view/581
<div><p class="CJ-Abstracttext">Zeolite is of a significance for geopolymers as it is a natural precursor and does not require additional heat treatment for activation. However, aluminosilicates sourced from natural sources require additional handling for the best use of exploitation. In this study, geopolymers were synthesized by binary use of zeolite and fly ash as main binding material and sodium silicate and sodium hydroxide as alkaline activator. The influence of alkaline activator ratios and sodium hydroxide concentrations on the compressive strength and flexural strength of the zeolite-fly ash based geopolymers were studied. In this research, zeolite-fly ash based geopolymer mortars were produced by using 50% of natural zeolite (clinoptilolite) and 50% of C-type fly ash. Four different activator ratios (Na<sub>2</sub>SiO<sub>3</sub>/NaOH: 1, 1.5, 2 and 2.5) and two sodium hydroxide molarities (10M and 12M) was utilized to activate zeolite and fly ash in order to determine the effect of these parameters on the mechanical strengths of the produced geopolymer mortars. The results indicated that as the alkaline activator ratio and NH molarity were increased the compressive strength of the zeolite-fly ash based geopolymers also increased. The maximum compressive and flexural strength values obtained after 28 days of curing were 20.1 MPa and 5.3 MPa respectively and corresponds when used activator ratio of 2.5 and sodium hydroxide concentration of 12 molarity. The obtained results indicated that both the alkaline activator ratio and sodium hydroxide concentration affected the compressive and flexural strengths of zeolite-fly ash based geopolymer mortar specimens.</p></div>Roble İbrahim LibanÜlkü Sultan KeskinOğuzhan Öztürk
Copyright (c) 2021 by the Authors. This is an open access article distributed under the CC BY licence.
2021-09-152021-09-151519610310.20528/cjcrl.2021.03.003Diffusion study of chloride and binding of water in concrete pore by molecular dynamics simulation using LAMMPS
https://challengejournal.com/index.php/cjcrl/article/view/561
<div><p class="CJ-Abstracttext">As for the communication between concrete and the particles, the surface shows Cl− shock and Na adsorption. With expanded particle focus, the solid adsorption capacity for Cl− is upgraded as a result of a detailed overview of the dynamic molecular simulation studies examining the chloride diffusion coefficient. Different characteristics of the diffusion process, including molecular models, system-size effects, temperature, and pressure conditions, and the type of protection, are discussed. This paper focus on Molecular Dynamic Simulation to determine the diffusion coefficient of chloride ion and water molecules in concrete. The diffusion coefficient for NaCl salt obtained 6.60178x10<sup>-10</sup>m<sup>2</sup>/s and the diffusion coefficient for CaCl<sub>2</sub> salt obtained 7.29305x10<sup>-10</sup>m<sup>2</sup>/s. So, the average chloride diffusion coefficient 6.9475x10<sup>-10</sup>m<sup>2</sup>/s. Diffusion coefficient obtained from graph 5.562x10<sup>-10</sup>m<sup>2</sup>/s. Diffusion coefficients for water molecules for NaCl solution are 6.125x10<sup>-10</sup>m<sup>2</sup>/s, 6.85x10<sup>-10</sup>m<sup>2</sup>/s, 1.044x10<sup>-10</sup>m<sup>2</sup>/s, 8.525x10<sup>-10</sup>m<sup>2</sup>/s, 6.25x10<sup>-10</sup>m<sup>2</sup>/s. diffusion coefficient of water molecules in CaCl<sub>2</sub> solution are 4.5x10<sup>-10</sup>m<sup>2</sup>/s, 6.725x10<sup>-10</sup>m<sup>2</sup>/s, 1.254x10<sup>-10</sup>m<sup>2</sup>/s, 7.725x10<sup>-10</sup>m<sup>2</sup>/s, 1.3x10<sup>-10</sup>m<sup>2</sup>/s. Average value obtained for water molecule diffusion are 4.545x10<sup>-10</sup>m<sup>2</sup>/s, 7.4062x10<sup>-10</sup>m<sup>2</sup>/s and 1.149x10<sup>-10</sup>m<sup>2</sup>/s. This diffusion of chloride effects the binding of water in concrete pore.</p></div>Md. Shafiqul IslamSayem AhmeedSumon Kumar Ghosh
Copyright (c) 2021 by the Authors. This is an open access article distributed under the CC BY licence.
2021-09-152021-09-15151889510.20528/cjcrl.2021.03.002Effect of retardant admixtures type and their using method on the behavior of concrete
https://challengejournal.com/index.php/cjcrl/article/view/585
<div><div><p class="CJ-Abstracttext">Construction sites may be exposed to crisis conditions during the casting process, resulting in delays of several hours and causing destruction of ready-mix concrete. This study suggests an experimental analysis of the possibility of using a specific additional dose of retardant admixtures, which may be used to ready-mix concrete before the initial setting of the concrete occurs. The effect of this additional dose on concrete characteristics in terms of workability, setting time, and compressive strength is also being studied. To conduct this investigation, three types of retardant admixtures from three branded companies were used. In addition, a penetration resistance experiment was conducted on the concrete to determine its setting time. The setting time of concrete was measured at different period intervals depending on when the additional dose of the retardant admixtures was added from the start of the concrete mixing. The results showed that concrete maintained proper workability for a period of more than 5 hours after using the additional dose of retarding admixtures. The additional dose of retarding admixtures not only delayed the concrete setting but also improved the compressive strength of the concrete. This implies that the use of an additional dose of retardant admixtures specifically tailored for ready-mix concrete is an effective option to avoid the return of ready-mixed fresh concrete.</p></div></div>Tamer Ibrahim AhmedMohamed Roshdy Afify
Copyright (c) 2021 by the Authors. This is an open access article distributed under the CC BY licence.
2021-09-152021-09-1515110411310.20528/cjcrl.2021.03.004Mechanical properties and freeze-thaw resistances of bronze-concrete composites
https://challengejournal.com/index.php/cjcrl/article/view/555
<div><p class="CJ-Abstracttext">Studies in the literature show that the physical and mechanical properties of concrete could be improved by the incorporation of different kinds of industrial waste, including waste tire rubber and tire steel. Recycling of waste is important for economic gain and to curb environmental problems. In this study, finely ground CuAl10Ni bronze is used to improve the physical and mechanical properties, and freeze-thaw resistances of C30 concrete. The density, cold crushing strength, 3-point bending strength, elastic modulus, toughness, and freeze-thaw resistances of concrete are determined. In addition, the Schmidt Rebound Hammer (SRH) and the ultrasonic pulse velocity (UPV) tests, which are non-destructive test methods, are applied. SEM/EDX analyses are also carried out. It is noted that a more compacted structure of concrete is achieved with the addition of bronze sawdust. Then higher density and strength values are obtained for concretes that are produced by bronze addition. In addition, concretes including bronze sawdust generally show higher toughness due to high plastic energy capacities than pure concrete.</p></div>Tuba BahtliNesibe Sevde Ozbay
Copyright (c) 2021 by the Authors. This is an open access article distributed under the CC BY licence.
2021-06-232021-06-23151394810.20528/cjcrl.2021.02.001Properties of Portland cement concrete cast with magnetized water: a review
https://challengejournal.com/index.php/cjcrl/article/view/570
<div><p class="CJ-Abstracttext">The water utilized in concrete manufacture plays an important role within the concrete mix, beginning from controlling the process of hydration of cement, besides appropriate curing to achieve the required strength, not to mention controlling the workability and durability of the concrete structure. The utmost significant challenge for concrete technology is to improve the properties of concrete. Nowadays, the engineering field needs to produce structures in harmony with the concept of sustainable development through the utilization of high-performance materials with an eco-friendly impact that is produced at a low-cost. The magnetic water (MW) provides one of the utmost towards this objective. The cost of magnetizing water is low because of the simple instruments used and the cost can be adapted to the scale of the work. In the last two decades, a new technology, so-called MW technology, has been extended to use in concrete manufacturing. Therefore, currently, the researchers are interested in the use of MW in the manufacture of cementitious materials helping to rationalize the cement usage and reducing reliance on chemical additives that have a negative environmental impact. Consequently, this paper presents the effect of the magnetization process in the structure of water molecules, the main properties of water. Additionally, the effect of using MW on the fresh and mechanical properties, as well as the durability characteristics and performance of cementitious materials have been reviewed. Moreover, the factors that affect the magnetization process of water, which highlighted discuss in this study. The results revealed that using MW significantly enhances the flowability and the characteristic strengths of cementitious materials as well as the durability properties.</p></div>Mariam Farouk GhazyMetwally Abd Allah Abd ElatyOmar Hussein Khalifa
Copyright (c) 2021 by the Authors. This is an open access article distributed under the CC BY licence.
2021-06-232021-06-23151587110.20528/cjcrl.2021.02.003Ductility of simply supported rubberized concrete beams
https://challengejournal.com/index.php/cjcrl/article/view/567
<div><div><div><p class="CJ-Abstracttext">Dispose of waste rubberized tires become a dangerous problem around the world, represented a big serious risk to the sur-rounded environment. Many studies show that over 1000 million tires reach their expired date yearly and this figure is anticipated to be 5000 million tires by reaching 2030. A minor part of them is employed as recycled materials and the residual amount is stockpiled or buried. This paper aimed to successfully utilize the vast amounts of tire rubber waste existing currently in landfills. This paper represents a practical investigation of the ductility performance of the reinforced rubberized concrete beams. Thirteen reinforced concrete beams simply supported, with waste rubber tires mixtures vary from 0 to 8 percentage as aggregates replacements, were tested by mid-span load. Therefore, to examine the ductility performance of reinforced rubberized concrete beams, three sets of samples were made. In the first group, coarse aggregates in the concrete mix were replaced by different percentages of the waste rubber partials, while for the second group, crumb rubber was replaced for the fine aggregates, and for the third one, a mix of waste and crumbed rubber were replaced for both types of aggregates. Experimental results of rubberized specimens were also compared with that of the reference beam (without rubber replacement), the comparison results declare that concrete contains rubber particles is less ductile than conventional concrete.</p></div></div></div>Ahmed Youssef Kamal
Copyright (c) 2021 by the Authors. This is an open access article distributed under the CC BY licence.
2021-06-232021-06-23151495710.20528/cjcrl.2021.02.002