Publisher: TULPAR Academic Publishing   (Total: 2 journals)   [Sort by number of followers]

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Challenge J. of Concrete Research Letters     Open Access   (Followers: 7)
Challenge J. of Structural Mechanics     Open Access   (Followers: 8)
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Challenge Journal of Concrete Research Letters
Number of Followers: 7  

  This is an Open Access Journal Open Access journal
ISSN (Online) 2548-0928
Published by TULPAR Academic Publishing Homepage  [2 journals]
  • Cover & Contents Vol.12 No.1

    • Authors: Journal Management CJCRL
      PubDate: 2021-03-12
      Issue No: Vol. 12, No. 1 (2021)
  • Effect of high temperature on SCC containing fly ash

    • Authors: Mehmet Canbaz, Erman Acay
      Pages: 1 - 11
      Abstract: The effect of high temperature on self-compacting concrete, which contains different amounts of fly ash, has been investigated. By considering the effect of concrete age and increased temperatures, the optimum fly ash-cement ratio for the optimum concrete strength is determined using experimental studies. Self-compacting concrete specimens are produced, with fly ash/cement ratios of 0%, 20% and 40%. Specimens were cured for 28, 56 and 90 days. After curing was completed, the specimens were subjected to temperatures of 20°C, 100°C, 400°C, 700°C and 900°C for three hours. After the cooling process, tests were performed to determine the unit weight, ultrasonic pulse velocity and compressive strength of the specimens. According to the experiment results, an increase in fly ash ratio causes a decrease in the compressive strength of self-compacting concrete. However, it positively contributes to self-compaction and strength loss at high temperatures. The utilization of fly ash in concrete significantly contributes to the environment and the economy. For this reason, the addition of 20% fly ash to concrete is considered to be effective.
      PubDate: 2021-03-12
      DOI: 10.20528/cjcrl.2021.01.001
      Issue No: Vol. 12, No. 1 (2021)
  • Application of an artificial neural network for predicting compressive and
           flexural strength of basalt fiber added lightweight concrete

    • Authors: Gokhan Calis, Sadık Alper Yıldızel, Ülkü Sultan Keskin
      Pages: 12 - 19
      Abstract: Concrete is known as one of the fundamental materials in construction with its high amount of use. Lightweight concrete (LWC) can be a good alternative in reducing the environmental effect of concrete by decreasing the self-weight and dimensions of the structure. In order to reduce self-weight of concrete artificial aggregates, some of which are produced from waste materials, are utilized, and it also contributes to develop a sustainable material Artificial neural networks have been the focus of many scholars for long time with the purpose of analyzing and predicting the lightweight concrete compressive and flexural strengths. The artificial neural network is more powerful method in terms of providing explanation and prediction in engineering studies. It is proved that the error rate of ANN is smaller than regression method. Furthermore, ANN has superior performance over nonlinear regression model. In this paper, an ANN based system is proposed in order to provide a better understanding of basalt fiber reinforced lightweight concrete. In the regression analysis predicted vs. experimental flexural strength, R-sqr is determined to be 86%. The most important strength contributing factors were analyzed within the scope of this study.
      PubDate: 2021-03-12
      DOI: 10.20528/cjcrl.2021.01.002
      Issue No: Vol. 12, No. 1 (2021)
  • Study on concrete proportioning methods: a qualitative and economical

    • Authors: Shoib Bashir Wani, Tahir Hussain Muntazari, Nusrat Rafique
      Pages: 20 - 29
      Abstract: The various approaches, established for concrete mix design, are not universal because design mixes are explicit to local climate, available materials, and type of exposure. The new-generation mix design method should be developed based on the performance criteria. The concrete strength obtained from the designed concrete mix and optimum cement content should not be considered as the only parameter for the suitability of the concrete mix. This study was carried to compare the proportioning of concrete mixes obtained by following procedures of Indian Standard (IS), American Concrete Institute (ACI) and British Standard (BS) of concrete mix design without the use of admixtures to validate for use in a moderate climate like Kashmir, India. The concrete mixes have been prepared with the necessary 28 days resistance in compression as “15 MPa, 20 MPa, 25 MPa, 30 MPa and 35 MPa”. The assessment of water-cement (w/c) ratio; cement, water, fine aggregate (FA) and coarse aggregate (CA) proportion was carried. The w/c ratio among all formulated mixes is significantly high in the BS method and low for IS method. The BS method uses less quantity and IS method uses the maximum quantity of cement. In addition, the ratio of total aggregate content (TAC) and the aggregate-cement ratio is higher in BS design method as compared to IS and ACI design methods. The aggregate content in ACI mix design appears to be consistent and it added to the relative high compressive strength. The specimens cast following BS guidelines failed to attain the target mean strength (TMS) due to a higher volume of aggregate content, high w/c proportion, less quantity of cement in the mix. The specimens cast by ACI and IS mix design upon compression testing showed higher results than the calculated TMS. The cost analysis per cubic meter of concrete revealed that IS and ACI mix proportioning are expensive than BS method. The IS procedure results in dense concrete followed by ACI procedure. It is expected that with a comprehensive investigation on selected design parameters concentrating more on local challenges, the present study will floor the way for the development and adoption of performance-based design mix selection for moderate climate.
      PubDate: 2021-03-12
      DOI: 10.20528/cjcrl.2021.01.003
      Issue No: Vol. 12, No. 1 (2021)
  • Effect of different fiber types on the mechanical properties of normal and
           high strength concrete at elevated temperatures

    • Authors: Mohamed Amin, Khaled Abu el-hassan
      Pages: 30 - 38
      Abstract: The effects of the types of fibers on mechanical properties of normal and high strength concrete under high temperature, up to 700 °C, was investigated. Three different- type fiber; "Steel Fiber (SF), Glass Fiber (GF) and Polypropylene Fiber (PPF)" are added into the concretes in five different ratios (0, 0.50, 1.00, 1.50 and 2.0%)of the volume under the following temperatures; 22, 100, 400 and 700°C. The results indicate that all the different types of fibers researched contribute to both the compressive and flexural strengths of concrete under high temperature, however, it is also found that this contribution decreases with an increase in temperature. The flexural strengths and compressive strengths for NSC and HSC mixes at 28 days under high temperature decreases as the temperature increases especially up to 400°C. Also, the best compressive and flexural strengths performance under high temperature was also those of SF. The compressive strength of the concrete incorporating SF was reduced under high temperature only, while the mixes containing PPF and GF were reduced under high temperature or with fiber addition. The optimum fiber addition ratios of the mixes containing PPF and GF are between 0.5-1.0 percent by volume. And for SF, it is 1.5% by the volume.
      PubDate: 2021-03-12
      DOI: 10.20528/cjcrl.2021.01.004
      Issue No: Vol. 12, No. 1 (2021)
  • Cover & Contents Vol.11 No.4

    • Authors: CJCRL Journal Management
      PubDate: 2020-12-20
      Issue No: Vol. 12, No. 1 (2020)
  • Cover & Contents Vol.11 No.3

    • Authors: CJCRL Journal Management
      PubDate: 2020-09-08
      Issue No: Vol. 12, No. 1 (2020)
  • Cover & Contents Vol.11 No.2

    • Authors: CJCRL Journal Management
      PubDate: 2020-06-17
      Issue No: Vol. 12, No. 1 (2020)
  • Cover & Contents Vol.11 No.1

    • Authors: CJCRL Journal Management
      PubDate: 2020-03-25
      Issue No: Vol. 12, No. 1 (2020)
  • Properties of steel fiber self-compacting concrete incorporating quarry
           dust fine powder

    • Authors: Joseph Abah Apeh, Juliet Eyum Ameh
      Pages: 1 - 10
      Abstract: Self-compacting concrete (SCC) has great potentials as it offers several environmental, economic and technical benefits. Moreover, the use of fibers extends its possibilities since fibers arrest cracks and retard their propagation. Incorporation of Quarry Dust (QD) in SCC help to reduce environmental hazards during the production of QD. This study evaluated the fresh and hardened properties of steel fiber self-compacting concrete (SFSCC) incorporating QD. The optimum fiber and QD contents with no adverse effects on fresh and hardened properties were determined. A comparative study on behavior of SCC and SFSCC mixtures in terms of workability, compressive strength, compressive strength development ratio, tensile, flexural and energy absorption capacity was carried out. Test results showed that compressive strength increased with increase in QD contents at fixed fiber content by mass of Portland cement (PC) and then decreased. Strength development ratio (C28/C7) for SCC was 1.13, while it was 1.06, 1.08, 1.10 and 1.01 after reinforcing with 0.10, 0.20 and 0.30 contents of fiber. The compressive, tensile, flexural and energy absorption capacity or Toughness of SFSCC increased with the inclusion of the aforementioned contents of steel fiber up to 0.20 % volume of total binder at constant QD content and then decreased when compared with control SCC values. From these results, optimum value for the variables studied was obtained from mix QD20 + 0.2fr. Hence, steel fiber and QD could be successfully used in SCC production not minding the slight draw back on workability of SCC caused by inclusion of steel fiber, but with a modified dosage of super-plasticizer (SP), fresh and hardened properties, in accordance with specifications in relevant code(s) can be achieved.
      PubDate: 2020-03-25
      DOI: 10.20528/cjcrl.2020.01.001
      Issue No: Vol. 12, No. 1 (2020)
  • Destructive and non-destructive testing of bronze-waste tire-concrete

    • Authors: Tuba Bahtlı, Nesibe Sevde Özbay
      Pages: 11 - 15
      Abstract: In this study, the effects of finely-milled bronze and waste tire on the mechanical properties of concrete have been investigated. Approximately 2.5% and 5% by weight for each additive (bronze sawdust and waste tire) were added to dry concrete. The open porosity, density, compressive strength values of cured concrete have been determined. In addition, the Schmidt rebound hammer (SRH) and the ultrasonic pulse velocity (UPV) tests, which are non-destructive test methods, were applied. The microstructure and fracture surfaces of these materials were characterized by scanning electron microscopy (SEM). It was observed that the density of pure concrete was 2.35 g/cm3 while the density was 2.19 g/cm3 for a C+5%B+5%T material. Similarly, pure concrete had an almost three times better compressive strength and a two times better SRH value than those of the C+5%B+5%T material. The density and mechanical properties of concrete materials containing bronze and waste tire decreased due to micro crack formations, weak bonding and deep cracks forming especially between the concrete and additives.
      PubDate: 2020-03-25
      DOI: 10.20528/cjcrl.2020.01.002
      Issue No: Vol. 12, No. 1 (2020)
  • Exploring optimum percentage of fly-ash as a replacement of cement for
           enhancement of concrete properties

    • Authors: Sarvat Gull, Shoib B. Wani, Ishfaq Amin
      Pages: 16 - 25
      Abstract: Researchers and decision makers are continuously looking out to determine the potential and effectiveness of fly-ash as a partial replacement of cement in concrete. The current study is carried out to check the optimum or nearly optimum quantity of fly-ash with which cement should be replaced to get most of the properties of concrete enhanced and to give the idea about the quantities of fly-ash that can be used in a better way and better cause so that a proper management scheme of its usage and disposal can be implied. Further, a comparison is given between normal concrete and fly-ash concrete to show the properties which can be enhanced by proper utilization of fly-ash as a partial replacement of cement. After carrying out the lab experiments, it has been seen that the replacement of fly-ash in concrete has resulted in general increase in compressive strength, flexural strength and splitting tensile strength up to 15% replacement and after then the strength is decreased considerably than that of normal concrete. Addition of fly-ash in concrete has resulted in decrease in the water absorption of concrete and hence decreases in permeability of concrete. There is a progressive increase in workability with increase in percentage of fly-ash in concrete. The current study has led to a conclusion that in order to achieve best results in use of fly-ash concrete, the fly-ash used for replacing cement in concrete should have the required properties as specified by the standards and proper techniques of processing fly-ash as well as mixing of fly-ash with cement must be employed.
      PubDate: 2020-03-25
      DOI: 10.20528/cjcrl.2020.01.003
      Issue No: Vol. 12, No. 1 (2020)
  • Metaheuristic algorithms in optimum design of reinforced concrete beam by
           investigating strength of concrete

    • Authors: Serdar Ulusoy, Aylin Ece Kayabekir, Gebrail Bekdaş, Sinan Melih Nigdeli
      Pages: 26 - 30
      Abstract: The locations of structural members can be provided according to architectural projects in the design of reinforced concrete (RC) structures. The design of dimensions is the subject of civil engineering, and these designs are done according to the experience of the designer by considering the regulation suggestions, but these dimensions and the required reinforcement plan may not be optimum. For that reason, the dimensions and detailed reinforcement design of RC structures can be found by using optimization methods. To reach optimum results, metaheuristic algorithms can be used. In this study, several metaheuristic algorithms such as harmony search, bat algorithm and teaching learning-based optimization are used in the design of several RC beams for cost minimization. The optimum results are presented for different strength of concrete. The results show that using high strength material for high flexural moment capacity has lower cost than low stretch concrete since doubly reinforced design is not an optimum choice. The results prove that a definite metaheuristic algorithm cannot be proposed for the best optimum design of an engineering problem. According to the investigation of compressive strength of concrete, it can be said that a low strength material are optimum for low flexural moment, while a high strength material may be the optimum one by the increase of the flexural moment as expected.
      PubDate: 2020-06-17
      DOI: 10.20528/cjcrl.2020.02.001
      Issue No: Vol. 12, No. 1 (2020)
  • Reliability analysis of a reinforced concrete bridge under moving loads

    • Authors: Hakan Bayrak, Ferhat Akgül
      Pages: 31 - 38
      Abstract: This study presents a reliability analysis procedure for a reinforced concrete bridge exposed to different moving loads. Bridges are one of the important part of transportation infrastructure systems. As bridges age, structural weakening due to heavy traffic and aggressive environmental factors lead to an increase in repair frequency and decrease in load carrying capacity. Therefore, bridges require periodic maintenance and repair in order to function and be reliable throughout their lifetimes. In other words, condition and safety of the bridges must be monitored at regular time intervals to avoid the disadvantages of deterioration. Otherwise, sudden collapse of a bridge may lead to irreversible loss of life and property. Therefore, the importance of the structural assessment of bridges is rapidly increasing in developed countries. In this study, reliability analysis which is one of the structural performance prediction method is applied to a reinforced concrete bridge subjected to the different moving loads. The aim of this study is to observe the safety of the bridge for the effect of the increasing traffic factor over the years.
      PubDate: 2020-06-17
      DOI: 10.20528/cjcrl.2020.02.002
      Issue No: Vol. 12, No. 1 (2020)
  • Investigation of optimal designs for concrete cantilever retaining walls
           in different soils

    • Authors: Esra Uray, Serdar Çarbaş, İbrahim Hakkı Erkan, Murat Olgun
      Pages: 39 - 45
      Abstract: In this paper, the investigation of the optimum designs for two types of concrete cantilever retaining walls was performed utilizing the artificial bee colony algorithm. Stability conditions like safety factors sliding, overturning and bearing capacity and some geometric instances due to inherent of the wall were considered as the design constraints. The effect of the existence of the key in wall design on the objective function was probed for changeable properties of foundation and backfill soils. In optimization analysis, wall concrete weight which directly affect parameters such as carbon dioxide emission and the cost was considered as the objective function and analyzes were performed according to different discrete design variables. The optimum concrete cantilever retaining wall designs satisfying constraints of stability conditions and geometric instances were obtained for different soil cases. Optimum designs of concrete cantilever retaining wall with the key were attained in some soil cases which were not found the feasible optimum solution of the concrete cantilever retaining wall. Results illustrate that the artificial bee colony algorithm was a favorable metaheuristic optimization method to gain optimum designs of concrete cantilever retaining wall.
      PubDate: 2020-06-17
      DOI: 10.20528/cjcrl.2020.02.003
      Issue No: Vol. 12, No. 1 (2020)
  • Effect of catalysts amount on mechanical properties of polymer concrete

    • Authors: Ferit Cakir, Pinar Yildirim, Mustafa Gündoğdu
      Pages: 46 - 52
      Abstract: Polymer materials are used in different engineering applications because of their excellent engineering properties. The use of these materials in different engineering fields has increased in recent years. It is predicted that polymer materials will be one of the most remarkable and popular engineering materials in the near future because of their unique properties. This paper focuses on Methyl Ethyl Ketone Peroxide (MEKP), which is one of the main catalysts and investigate its effect on the mechanical properties of Polymer Concrete (PC). The main aims of the study are to understand the mechanical properties of the polymer concrete including different amount of MEKP and to investigate the influence of MEKP on the mechanical characterizations of the PCs. For this purpose, five different samples containing 0.15% (Mixture-1), 0.25% (Mixture-2), 0.35% (Mixture-3), 0.45% (Mixture-4) and 0.55% (Mixture-5) MEKP of the total weight were prepared and some experimental studies were performed on the prepared mixtures. The obtained strength values were discussed and evaluated effect of MEKP on mechanical properties of PCs.
      PubDate: 2020-09-08
      DOI: 10.20528/cjcrl.2020.03.001
      Issue No: Vol. 12, No. 1 (2020)
  • Analytical and experimental study on shear performance of RCC beam
           elements reinforced with PSWC rebars: a comparative study

    • Authors: Shoib Bashir Wani, Sarvat Gull, Ishfaq Amin, Ayaz Mohmood
      Pages: 53 - 68
      Abstract: Early distress in RCC (Reinforced Cement Concrete) structures in the recent times poses a major problem for the construction industry. It is found that in most of cases, distresses in reinforced concrete structures are caused by corrosion of rebar embedded in the concrete. The HYSD (High Yield Strength Deformed)  rebars which are used to offer excellent strength properties is detrimental to durability due to action of ribs as stress concentrators. Nowadays, concept of PSWC rebars (plain surface with wave type configuration rebars, formerly known as C-bars/mild steel rebar with curvy profile) is emerging to have a compromise between strength and durability. This investigation assesses the flexural behaviour of RCC elements reinforced with PSWC rebars. The flexural performance of RC beams of size 1000mm x 150mm x 150mm reinforced with PSWC rebars at 4mm and 6mm deformation level was studied by conducting test as per IS 516-1959 under four point loading. The performance of PSWC bar reinforced elements are compared with beams reinforced with mild steel rebars, HYSD rebars with spiral and diamond rib configuration to assess the viability of PSWC rebars to replace conventional reinforcement. The test results are validated by numerical analysis with the help of ANSYS software. Totally 15 beams are subjected to flexure test and the performance evaluators are first crack load, deflection at first crack load, ultimate load carrying capacity, deflection at ultimate load, load-deflection behaviour, load-strain behaviour and failure pattern. It is found that PSWC rebars as reinforcement in concrete beams enhanced the ductile behaviour of beams as compared to conventional HYSD and mild steel rebar beams. The energy absorbing capacity has increased significantly for beams reinforced with PSWC rebars when compared with conventional HYSD and mild steel rebar beams. The load-deflection behaviour and failure mode of PSWC rebars reinforced concrete beams were found to be similar to that of high yield strength rebars irrespective of deformation level. The analytical investigation from ANSYS software gave good agreement with the experimental results. It is concluded that PSWC bar has the potential to replace conventional HYSD rebar. Further study needs to be done to optimize the profile level and stirrup locations; and usage with high concrete grade for effective exploitation.
      PubDate: 2020-09-08
      DOI: 10.20528/cjcrl.2020.03.002
      Issue No: Vol. 12, No. 1 (2020)
  • Fracture patterns and mechanical properties of GFRP bars as internal
           reinforcement in concrete structures

    • Authors: Mehmet Canbaz, Uğur Albayrak
      Pages: 69 - 74
      Abstract: Glass Fiber Reinforced Plastic (GFRP) composites as rolled bars can be used as steel rebar to prevent oxidation or rust which is one of the main reasons concrete structures deteriorate when exposed to chlorides and other harmful chemicals. GFRP is successful alternative for reinforcement with high tensile strength- low strain, corrosion resistance and congenital electromagnetic neutrality in terms of longer service life. The main goal of the study is to investigate the mechanical and bonding properties of GFRP bars and equivalent steel reinforcing bars then compare them. GFRP and steel rebar are embedded in concrete block with three different levels. Mechanical properties of GFRP and steel bars in terms of strength and strains are determined. On the other hand; modulus of elasticity of GFRP and steel bars, modulus of toughness and modulus of resilience were calculated using stress-strain curves, as a result of the experiments. Pull-out tests are conducted on each GFRP and rebar samples which are embedded in concrete for each embedment level and ultimate adherence strengths are determined in terms of bar diameter–development length ratio. Yield strength, strain and modulus of elasticities of GFRP samples are compared to steel rebar. According to the test results reported in this study, GFRP bars are used safely instead of steel bars in terms of mechanical properties.
      PubDate: 2020-09-08
      DOI: 10.20528/cjcrl.2020.03.003
      Issue No: Vol. 12, No. 1 (2020)
  • Comparative study of optimum cost design of reinforced concrete retaining
           wall via metaheuristics

    • Authors: Aylin Ece Kayabekir, Melda Yücel, Gebrail Bekdaş, Sinan Melih Nigdeli
      Pages: 75 - 81
      Abstract: Design engineers may find various options of metaheuristic method in optimization of their problems. Because of the randomization nature of metaheuristic methods, solutions may trap to non-optimum solutions which are just optimums in a limited part of the selected range of the design variables. Generally, metaheuristics use several options to prevent this situation, but the same optimization process may solve different performances in every run of the process. Due to that, a comparative study by using ten different algorithms was done in this study. The optimization problem is the cost minimization of an L-shaped reinforced concrete (RC) retaining wall. The evaluation is done by conducting 30 multiple cycles of optimization, and comparing minimum cost, average cost and standard deviation values.
      PubDate: 2020-09-08
      DOI: 10.20528/cjcrl.2020.03.004
      Issue No: Vol. 12, No. 1 (2020)
  • The physico-mechanical properties of concrete with red-mud at high

    • Authors: Ibrahim A. Alameri, Meral Oltulu
      Pages: 82 - 91
      Abstract: Reuse of treated waste can provide significant environmental, social and economic benefits. It is necessary to use it in the right places while keeping the properties of the waste in mind. Aluminum-rich wastes such as red mud derived from bauxite may be used in places exposed to high temperatures. This article discusses the effects of high temperatures of 25, 200, 300, 400, 600 and 800°C and 3 hours of exposure on concrete samples replaced by red mud at 0, 10, 15 and 20%. To study the concrete’s mechanical and permeability properties, loss in weight, compressive strength, splitting tensile strength, capillary water absorption and water permeability tests were performed for all mixes. Results were closer to those of the control specimen, which ultimately supported the use of red mud at a ratio of 10%.
      PubDate: 2020-12-20
      DOI: 10.20528/cjcrl.2020.04.001
      Issue No: Vol. 12, No. 1 (2020)
  • Influence of nano-modification on mechanical and durability properties of
           cement polymer anticorrosive coating

    • Authors: Shoib Bashir Wani, Junaid Ahmed, M. S. Haji Sheik Mohammed, Tahir Hussain Muntazari, Nusrat Rafique
      Pages: 92 - 104
      Abstract: In the present study performance evaluation of nano-modified cement polymer anticorrosive coating (CPAC) was undertaken by conducting the Chemical Resistance Test (CRT), Applied Voltage Test (AVT), Bond Strength Test (BST), Accelerated Corrosion Test (ACT) and Coating Flexibility Test (CFT). The site oriented coating comprises of nitrite, styrene-butadiene polymer and other additives. The anticorrosive polymer solution is compatible with concrete or cement when uniformly mixed with fresh ordinary portland cement (OPC). Totally forty-five specimens were subjected to various performance evaluation tests. In CRT observations were made on drilled and undrilled specimens after 45 days test period in liquid and vapour phase. The coating did not blister, soften and lose bond in all the tested medium during CRT and meet the requirement of BIS 13620-1993 and ASTM A775/A775M.The coating has the ability to withstand the electrochemical stresses during one-hour AVT. In the BST, single and double coated rebars showed +126.96% and +46.08% greater usable bond strength respectively than uncoated rebar. In the ACT, there is a significant escalation in time of cracking of specimens of double-coated reinforced rebars by 2 times as compared to uncoated rebars. Cracking time for single coated reinforced rebars was found 1.6 times more than uncoated rebars. In the CFT, coating completely in the inner and the outer radius of the 180° bend rebar fails to meet the requirements of BIS and ASTM standards. Thus the coating has to be applied subsequent to cutting and rebar twisting is finished.
      PubDate: 2020-12-20
      DOI: 10.20528/cjcrl.2020.04.002
      Issue No: Vol. 12, No. 1 (2020)
  • An investigation on the properties of woodcrete exposed to high

    • Authors: Mehmet Canbaz, İlkay Kara, İlker Bekir Topçu
      Pages: 105 - 111
      Abstract: By combining wood wastes with various binders, construction materials can be produced. These materials can be used in non-bearing parts such as wall block, insulation panel. In this study, prismatic specimens were taken from the mixtures produced considering the chip-cement ratio as 0.25, 0.5 and 1. The unit weight, ultrasonic pulse velocity, bending and compressive strengths of the specimens were determined by using the results of the experiments on these specimens. In addition, specimens were kept at 200 and 400°C for 3 hours in order to determine its behavior under high temperature, which is one of the most important problems for wood composites. With the experiments carried out on the cooled specimens, weight and strength losses, changes in ultrasonic pulse velocity were examined. As a result of the study, while determining that the chip-cement ratio can be used as 1, it is recommended to use the chip-cement ratio up to 0.5 when the high temperature effect is taken into consideration.
      PubDate: 2020-12-20
      DOI: 10.20528/cjcrl.2020.04.003
      Issue No: Vol. 12, No. 1 (2020)
  • Fracture properties of self-compacting fiber-reinforced concrete

    • Authors: Mariam Farouk Ghazy, Metwally Abd Allah Abd Elaty, Omar Daboun
      Pages: 112 - 121
      Abstract: Self-compacting concrete (SCC) is an innovative concrete that does not necessitate vibration for placing and compaction. Nineteen concrete mixes were investigated including a control mix without fibers as well as eighteen SCC with fibers (SCFRC) mixes. Three types of fibers (polypropylene, glass and steel) were used. Slump flow, L-box, V-funnel as well as column segregation tests were conducted to assess the fresh properties. Whereas, compressive, splitting tensile and flexural strengths were measured to assess the hardened properties of SCFRC. Three point bending tests were performed for the purpose of assessing the fracture properties of SCFRC. Test results showed that the inclusion of fibers to produce SCFRC mixtures remarkably enhanced the fracture properties including fracture energy (Gf) and fracture toughness (K1c). Inclusion of steel fibers with 2% volume fractions showed an improvement with 26.9 times for Gf over the control mix. Whereas, 104% increase in K1c was recorded for the same mix over the mix without fibers. Adding fibers to SCC to produce self-compacting fiber reinforced concrete (SCFRC) will expand its advantages. However, the application fields still need to understand the properties of SCFRC.
      PubDate: 2020-12-20
      DOI: 10.20528/cjcrl.2020.04.004
      Issue No: Vol. 12, No. 1 (2020)
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