• Nuclear Engineering and Technology
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• v.55 no.3
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• pp.876-883
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• 2023

Radioactive waste should be solidified before being disposed of in the repository to eliminate liquidity or dispersibility. Cement is a widely used solidifying media for radioactive waste, and cement solidified waste should satisfy the minimum compressive strength of the waste acceptance criteria of a radioactive repository. Although the compressive strength of waste should be measured by the test method provided by the waste acceptance criteria, the method differs depending on the operating repository of different countries. Considering the measured compressive strength changes depending on test conditions, the effect of test conditions should be analyzed to avoid overestimation or underestimation of the compressive strength during disposal. We selected test conditions such as the height-to-diameter ratio, loading rate, and porosity as the main factors affecting the compressive strength of cement solidified radioactive waste. Owing to the large variance in measured compressive strength, the effects of the test conditions were analyzed via statistical analyses using parametric and nonparametric methods. The results showed that the test condition of the lower loading rate, with a height-to-diameter ratio of two, reflected the actual cement content well, while the porosity showed no correlation. The compressive strength assessment method that reflects the large variance of strengths was suggested.

• Computers and Concrete
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• v.21 no.3
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• pp.345-353
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• 2018

This paper approaches to improve the mechanical and durability properties of low calcium fly ash geopolymer concrete with the addition of Alccofine as a mineral admixture. The mechanical and durability performance of GPC was assessed by means of compressive strength, flexural strength, permeability, water absorption and permeable voids tests. The correlation between compressive strength and flexural strength, depth of water penetration and percentage permeable voids are also reported. Test results show that addition of Alccofine significantly improves the mechanical as well as permeation properties of low calcium fly ash geopolymer concrete. Very good correlations were noted between the depth of water penetration and compressive strength, percentage permeable voids and compressive strength as well as between compressive strength and flexural strength.

• 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.

• Tunnel and Underground Space
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• v.7 no.2
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• pp.108-115
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• 1997

Uniaxial and biaxial compressive tests were conducted on limestone specimens containing artificial joints and a circular hole to investigate the influence of inclination and number of joints on compressive strength and deformation behavior of rock with a circular hole. Under uniaxial and biaxial compressive condition, the inclination of joints showing the maximum and minimum strength were 0$^{\circ}$ and 30$^{\circ}$ respectively, which was independent of the number of joints. Under uniaxial compressive condition, relative maximum strength of rock with n=1 and 3 to intact rock with a circular hole were 12.5%~82.8% and 11.4~62.5% respectively, and under biaxial compressive condition, 18.2~91.0% and 17.0~87.5% respectively. The influence of the number of joints on the decrease of compressive strength was greater under uniaxial than under biaxial compressive condition. Under uniaxial and biaxial compressive condition, axial and lateral deformations of rock showed the least values where $\alpha$=30$^{\circ}$. Under uniaxial compressive condition, axial and lateral deformation at maximum strength of rock have the increasing tendency with increase the number of joints. But they have the decreasing tendency under biaxial compressive condition. Under uniaxial and biaxial compressive conditions, axial deformation of circular hole was greater than lateral deformation without respect to the number of joints and the inclination of joints.

• Computers and Concrete
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• v.25 no.5
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• pp.401-409
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• 2020

Artificial neural networks are used as a useful tool in distinct fields of civil engineering these days. In order to control long-term quality of Self-Compacting Semi-Lightweight Concrete (SCSLC), the 90 days compressive strength is considered as a key issue in this paper. In fact, combined artificial neural networks are used to predict the compressive strength of SCSLC at 28 and 90 days. These networks are able to re-establish non-linear and complex relationships straightforwardly. In this study, two types of neural networks, including Radial Basis and Multilayer Perceptron, were used. Four groups of concrete mix designs also were made with two water to cement ratios (W/C) of 0.35 and 0.4, as well as 10% of cement weight was replaced with silica fume in half of the mixes, and different amounts of superplasticizer were used. With the help of rheology test and compressive strength results at 7 and 14 days as inputs, the neural networks were used to estimate the 28 and 90 days compressive strengths of above-mentioned mixes. It was necessary to add the 14 days compressive strength in the input layer to gain acceptable results for 90 days compressive strength. Then proper neural networks were prepared for each mix, following which four existing networks were combined, and the combinatorial neural network model properly predicted the compressive strength of different mix designs.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.1199-1202
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• 2001

The objective of this study is to examine the effect of frost damage immediately after placement on compressive strength of concrete. Obviously frost damage produced under low curing temperature at early ages causes the loss of compressive strength of concrete. In order to find the degrees of the loss of compressive strength, compressive strength tests was peformed at 7 and 28-day ages on concrete specimen with various curing temperature history. The results from the tests showed that the loss of compressive strength relative to concrete cured under isothermal temperature at $20^{\circ}C$ was generally from 20 to 50% for 7-day ages and below 20% for 28 day ages. Considering the serious loss of compressive strength over 50% for some cases, careful attention may be needed to placing of concrete under low atmospheric temperature.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2006.05a
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• pp.155-158
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• 2006

Deduction of compressive strength in concrete members is very important to decide stability of structures. In this study, we compare the compressive strength of concrete between nondestructive test done to the building which was to be demolished at residential reconstruction site and destructive test of core specimen from the site. The result is more reliable because ore can compare the measurement of nondestructive tell with the result from destructive test using drilled cores. Compressive strength of each material was calculated with the result of rebound number test. In addition, we performed ultrasonic test for another result of compressive strength. And we made a comparative study of compressive strength of concrete drawn from both nondestructive and destructive tests.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2020.11a
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• pp.96-97
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• 2020

In this study, the compressive strength and porosity characteristics of cement mortar mixed with liquid and powder composite water repellent were evaluated. When the liquid water repellent was mixed, the compressive strength at 28 days of age was 42% compared to OPC, and the compressive strength was greatly reduced. However, the 28-day compressive strength of the powder water repellent mixture and P5L1, P6L1 liquid and powder composite water repellent was about 97% compared to OPC, and there was little decrease in compressive strength.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.11a
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• pp.141-142
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• 2023

In this study, the correlation between the properties of concrete in the fresh state and the compressive strength of hardened concrete was analyzed. It was found that the compressive strength increased as the values of T500 and plastic viscosity increased. However, there is a relationship between T500, which is a qualitative method, and compressive strength, but it seems difficult to predict through this. However, the correlation between plastic viscosity and compressive strength appears to be high, and it is believed that compressive strength can be predicted, but more data will be collected in the future for additional analysis. I think this will be necessary.

• International Journal of Highway Engineering
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• v.20 no.3
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• pp.39-46
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• 2018

PURPOSES: This study is to estimate nondestructive strength equation based on probability for bridges using field test data. METHODS : In this study, a series of the field inspection and the test have been performed on 297 existing bridges, in order to evaluate the bridges, based on the test results of the in-depth inspection, and the estimated strengths by means of the nondestructive strength equations are analyzed and compared with results of the core specimen strengths. RESULTS : According to results of analyses, In case of standard design compressive strength of concrete is 18MPa, 21MPa, similar reliability of RILEM equation were 0.89~0.90, but in case of standard design compressive strength of concrete is 35MPa, 40MPa were 0.4~0.56. According to standard design compressive strength of concrete is 40MPa, similar reliability of ultrasonic pulse velocity method equation were 0.56. CONCLUSIONS :RILEM equation had high similar reliability than other equation in case of standard design compressive strength of concrete is 18MPa, 21MPa, but had low similar reliability than other equation in case of standard design compressive strength of concrete is 35MPa, 40MPa. and ultrasonic pulse velocity method equation had low similar reliability than other equation in case of standard design compressive strength of concrete is 40MPa.