• Magazine of the Korean Society of Agricultural Engineers
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• v.39 no.1
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• pp.83-92
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• 1997

An experimental study of the application of Silica fume for the high strength concrete was conducted. Nine specimens with three different contents of silica fume, 0%, 10%, 20% and with three water-cement ratio 30%, 40%, 50% were tested. Results shows that 10% of silica fume and 30% of water-cement ratio has a maximum strength with 700kg/$cm^2$ of compressive strength and 64kg/$cm^2$ of splitting tensile strength and 100kg/$cm^2$ of flexural strength. Slump value of the tested samples decreases with increasing water-cement ratio and elapsed time of silica fume. Splitting tensile strength$({\sigma}_f)$ and flexural strength $({\sigma}_f)$ and static modulus of elasticity(E) can be correlated with compressive strength $({\sigma}_c)$ from a regression analysis.

• Journal of the Korea Concrete Institute
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• v.11 no.4
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• pp.137-145
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• 1999

The use of steel fiber reinforced to improve the strength and flexural toughness of concrete is well known, but reinforcement of polymer concrete with steel fibers has been hardly reported till now. Polymer concrete has high strength, durability and freeze-thaw resistance than that of cement concrete, but it has disadvantage such as low flexural toughness. In this paper, the strength characteristics and flexural toughness of steel fiber reinforced polymer concrete are investigated experimentally with various steel fiber aspect ratios($\ell$/d), and contents(vol.%). As the result, the flexural and splitting tensile strengths and flexural toughness were increased aspect ratio, and reach the maximums at a aspect ratio of 50. The relationship between the compressive, flexural and splitting tensile strength were high. And the relationship between flexural strength and strain energy was approximately linear.

• Journal of the Korean Society of Safety
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• v.20 no.3 s.71
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• pp.126-133
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• 2005

Behavior of saw-dust concrete has not studied because many people have thought that saw-dust concrete cannot be applicable for structural member, up to now. This study is to findout how much the concrete can be structurally applicated. 5mm grid sieve was used to select satisfactory sawdust for better concrete quality. Test molds size of ${\phi}10{\times}20cm$ long were made of normal without sawdust, 0.05%, 0.1%, 0.2%, 0.4%, 0.6%, 0.8%, 1.0%, 1.2%, 1.4%, 1.6%, 1.8% 2.0%, for making concrete strengh of 180kg, 210kg, 240kg, 270kg which they are normally used in practice presently. A various strengths tests such as compressive splitting tensile, flexible strength behavior of structural member named beam using size of $20{\times}30{\times}120cm$ have been done for the structural aspects. Tensile strength shows that it can be more affected than higher strength of it.

• Advances in concrete construction
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• v.8 no.1
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• pp.1-7
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• 2019

The possibility of using recycled coarse glass aggregates as a substitute for natural crushed stone are relatively limited. In order to promote it for engineering application, this paper reports the effect of coarse glass aggregate on mechanical behavior of concrete. The coarse aggregates are substituted for coarse glass aggregate (CGA) as 0%,20%,40%,60%,80% and 100%.The results show that increasing the coarse glass aggregate content cause decrease in compressive strength, the elastic modulus, the splitting tensile strength, the flexural strength. An equation is presented to generate the relationship between cube compressive strength and prism compressive strength, the relationship between cube compressive strength and elastic modulus, the relationship between cube compressive strength and splitting tensile strength, the relationship between cube compressive strength and flexural strength of coarse glass concrete.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.11a
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• pp.23-24
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• 2023

This study attempted to derive an appropriate application range by reviewing the integration performance of joints according to the application range of SRA concrete. As a result, it was confirmed that the integration performance was improved even if SRA concrete was placed only by 75mm, which is 0.5 times the thickness of the member.

• International Journal of Concrete Structures and Materials
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• v.9 no.3
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• pp.337-343
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• 2015

Previous studies have shown that the drying shrinkage of recycled aggregate concrete (RAC) is greater than that of natural aggregate concrete (NAC). Drying shrinkage is the fundamental reason for the cracking of concrete, and tensile creep caused by the restraint of drying shrinkage plays a significant role in the cracking because it can relieve the tensile stress and results in the delay of cracking occurrence. However, up till now, all research has been focusing on the compressive creep of RAC. Therefore, in this study, a uniaxial restrained shrinkage cracking test was executed to investigate the tensile creep properties caused by the restraint of drying shrinkage of RAC. The mechanical properties, such as compressive strength, tensile splitting strength, and Young's modulus of RAC were also investigated in this study. The results confirmed that the tensile creep of RAC caused by the restraint of shrinkage was about 20-30 % larger than that of NAC.

• Advances in materials Research
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• v.8 no.2
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• pp.103-115
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• 2019

Polypropylene (PP) fibers for making fabric which is used for packing cement have a high strength and high tear resistance. Due to these excellent properties the present study investigates the effect of PP fibers on the mechanical strength of concrete. Mechanical strength parameters such as compressive strength, splitting tensile strength and flexural strength are evaluated. Structural integrity of concrete using Ultrasonic Pulse Velocity (UPV) was also studied. Concrete containing PP fibers in percentage of 0%, 0.15%, 0.25%, 0.5% and 0.75% was developed with a characteristic compressive strength of 25 MPa. Concrete cubes, cylinder and prismatic specimens were cast and tested. It was found that the UPV values recorded for all specimens were of the similar order. Test results indicated the used of PP fibers can significantly improve the flexural and splitting tensile strengths of concrete materials whereas it resulted a decreased in compressive strength. The relative increase in split tensile and flexural strength was optimum at a fiber dosage of 0.5% and a mild decreased were observed in 28 days compressive strength. The findings in this paper suggested that PP fibers deriving from these waste cement bags are a feasible fiber option for fiber-reinforced concrete productions.

• Steel and Composite Structures
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• v.39 no.1
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• pp.81-93
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• 2021

Splitting tensile strength (STS) is an important mechanical parameter of concrete. This study offers novel methodologies for the early prediction of this parameter. Artificial neural network (ANN), which is a leading predictive method, is synthesized with two metaheuristic algorithms, namely atom search optimization (ASO) and equilibrium optimizer (EO) to achieve an optimal tuning of the weights and biases. The models are applied to data collected from the published literature. The sensitivity of the ASO and EO to the population size is first investigated, and then, proper configurations of the ASO-NN and EO-NN are compared to the conventional ANN. Evaluating the prediction results revealed the excellent efficiency of EO in optimizing the ANN. Accuracy improvements attained by this algorithm were 13.26 and 11.41% in terms of root mean square error and mean absolute error, respectively. Moreover, it raised the correlation from 0.89958 to 0.92722. This is while the results of the conventional ANN were slightly better than ASO-NN. The EO was also a faster optimizer than ASO. Based on these findings, the combination of the ANN and EO can be an efficient non-destructive tool for predicting the STS.

• Journal of the Korea Concrete Institute
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• v.24 no.1
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• pp.53-60
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• 2012

The main object of this paper is to investigate the effects of high temperatures on the physical and mechanical properties of natural sand concrete(NSC) and crushed sand concrete(CSC). Test samples were exposed to high temperature ranging from $200^{\circ}C$ to $800^{\circ}C$. After exposure, various tests were conducted. Color image analysis and weight losses were determined and compressive strength test and splitting tensile strength test were conducted. The results indicated that weight losses increased as exposure temperature increased with comparable decreasing rate. The results also showed that compressive strength and splitting tensile strength and modulus of elasticity decreased as exposure temperature increased. The results also showed that residual compressive strength of NSC decreased more drastically than that of CSC at $200^{\circ}C$ and $400^{\circ}C$. Residual splitting tensile strength of NSC decreased more than that of CSC at $200^{\circ}C$, while NSC and CSC showed comparable residual strength ratio at $800^{\circ}C$.

• Journal of the Korean Society for Nondestructive Testing
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• v.35 no.2
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• pp.150-156
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• 2015

In this study, the effects of different mix proportions and fire scenarios (exposure temperatures and post-fire-curing periods) on fire-damaged concrete were analyzed using a nonlinear resonance vibration method based on nonlinear acoustics. The hysteretic nonlinearity parameter was obtained, which can sensitively reflect the damage level of fire-damaged concrete. In addition, a splitting tensile strength test was performed on each fire-damaged specimen to evaluate the residual property. Using the results, a prediction model for estimating the residual strength of fire-damaged concrete was proposed on the basis of the correlation between the hysteretic nonlinearity parameter and the ratio of splitting tensile strength.