• Advances in concrete construction
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• v.5 no.5
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• pp.481-492
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• 2017

The aim of this paper is to investigate the effect of quartz powder (Qp), quartz sand (Qs), and different water curing temperature on mechanical properties including 7, 14, 28-day compressive strength and 28-day splitting tensile strength of Ultra High Performance Concrete and also finding the correlation between these variables on mechanical properties of UHPC. The response surface methodology was monitored to show the influences of variables and their interactions on mechanical properties of UHPC, then, mathematical models in terms of coded variables were established by ANOVA. The offered models are valid for the variables between: quartz powder 0 to 20% of cement substitution by cement weight, quartz sand 0 to 50% of aggregate substitution by crushed limestone weight, and water curing temperature 25 to $95^{\circ}C$.

• Journal of the Korea Concrete Institute
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• v.27 no.3
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• pp.273-281
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• 2015

In this paper, the performance of alkali-activated slag cement (AASC) is assessed in terms of compressive strength and drying shrinkage, using three different types of silica sand and river sand. The sand type has an important influence on the properties of AASC mortar. Three silica sands (SS1, SS2 and SS3) and river sand (RS) were considered. Three series of blended sands have been tested. A first series (S1) with RS and SS1, a second series (S2) with RS and SS2 and third series (S3) with RS and SS3 with a different blended ratios. The result shows a very significant influence of the blended sand on the AASC mortar properties. The compressive strength and drying shrinkage related with the particle sizes and blended ratios of sands are investigated considering blended sand properties like fineness modulus (FM) and relative specific surface. The type and blended ratio of sand seems to have very significant and important consequences for the mix design of the AASC mortar.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.329-332
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• 2008

Recently, land sand is being used more because of the deficiency of river sand. In this paper, in order to manufacture high strength concrete in the range of 70MPa, the effect of sand/aggregate ratio and adding fly-ash. As results, we could come to conclusion that the reduction of sand/aggregate ratio caused the increase of fluidity in the range of $37{\sim}45%$ and the maximum strength was 77MPa obtained at S/a=39%, which could be considered as optimum S/a. Besides, we could also get a conclusion that the larger amount of fly-ash increased the fluidity within 20% of replacement ratio (fly-ash to cement ratio) and the compressive strength at the age of 28days was equal to or larger than that of plane concrete, which represented no replacement by fly-ash, at the same range. from the results, it could be seen that the optimum replacement ratio of fly-ash was in the range of $10{\sim}15%$.

• Structural Engineering and Mechanics
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• v.87 no.5
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• pp.499-516
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• 2023

To defend against harmful gamma radiation, new types of materials for use in the construction of heavyweight concrete (HWC) are still needed to be developed. This research introduces new materials to be employed as a partial replacement for fine aggregate (FA) to manufacture high-performance heavyweight concrete (HPHWC). These materials include hematite, black sand, ilmenite, and magnetite, with substitution ratios of 50% and 100% of FA. In this research, the hardening and fresh characteristics of HPHWC were obtained. Concrete samples' Gamma-ray linear attenuation coefficient was evaluated utilizing a gamma source of Co-60 through the thicknesses of 2.5, 5, 7.5, 10, 12.5, and 15 cm. High temperatures were studied for HPHWC samples, which were exposed to up to 700℃ for two hours. Energy-dispersive x-rays and a scanning electron microscope carried out microstructure analyses. Magnetite as an FA attained the lowest compressive strength of 87.1 MPa, but the best radiation protection characteristics and the highest density of 3100 kg/m³ were achieved. After 28 days, the attenuation efficiency of concrete mixtures was increased by 6.5% when fine sand was replaced with black sand at a ratio of 50%. HPHWC, which contains hematite, black sand, ilmenite, and magnetite, is designed to reduce environmental and health dangers and be used in medicinal, military, and civil applications.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.503-506
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• 2005

Recently, corrosion of reforcement of reinforced concrete structures and carbonation is raised problem of durability because of exhaustion of river sand and rapid increase of sea sand and also, concrete structure of sea environment is attacked to combined deterioration according to penetration of chloride ion and carbonation, change of temperature, repetition of dryness and wetness. Therefore, In this study, data base were presented to solve the problem about using sea sand to concrete structure situated in combined deterioration environment by exposuring concrete specimen contained chloride ion under the individual and combined deterioration.

• Magazine of the Korean Society of Agricultural Engineers
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• v.45 no.1
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• pp.45-54
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• 2003

The effects of binder content and silica sand content on the durability characteristics of lightweight polymer concretes are examined. As a result, the flame lingering times using unsaturated polyester resin and non-combustible polyester resin were 60∼120 and 0∼4 seconds respectively, and the combustion lengths were 9∼11 mm and 0∼3 mm, respectively. Thus it is believed that the lightweight polymer concrete was incombustible and the light weight polymer concrete in which non-combustible material was added was perfectly non-combustible. The percent of original mass of lightweight polymer concrete, according to the freezing-thawing experiment, was below 0.3 %, which was much less than that of cement concrete. The pluse velocity, for the case of the binder content 28 %, showed the minimum decreasing rate for the lightweight polymer concrete with silica sand content of 50 %. The higher the binder content, the greater the durability. That is much higher than other material and believed that the freezing-thawing was suppressed by a low absorption.

• Proceedings of the Korea Concrete Institute Conference
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• 1996.10a
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• pp.17-23
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• 1996

The objective of this study is to present the reference data about the influence of concrete properties using crushed sand, according to the change of powder content and grain shape. From the test results. We obtained that as powder content is increased, sand aggregate ratio, water content and S.P/C are increased in mixing design of concrete. The more powder content is the less slump and air content loss are decreased in fresh state, but the higher compressive strength and drying shrinkage are increased in hardened concrete state. As grain shape become round, water content is decreased in mixing design of concrete. And also, loss of slump and air content in fresh state, compressive strength in hardened state are increased.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.217-220
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• 2005

As this study is to test effects of sulfate attack on deterioration of concrete using in crushed aggregates. Besides tests have been carried out with concrete by river sand and crushed sand by fine sand, concrete mixes various proportions of slica fume and fly ash(up to 15$\%$ by weight fo cement) were prepared and immersed in pure water, sodium sulfate solution for 28 and 60days. Test on the change in the weight and compressive strength of concrete according to the duration of immersion time and the content of slica fume and fly ash was performed.

• Magazine of the Korea Concrete Institute
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• v.9 no.1
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• pp.153-163
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• 1997

This paper is an experimental study of the chemical resistance of mortar which contains silica sand particles. The possible use of silica sand particles in the future as an admixture for improving chemical resistance of mortar is examined in mortar model experiments. The possibility of using mortar model its prediction models for the chemical resistance of concrete is examined. The results obtained are as follows. Since the experimental results from the chemical resistance tests based on the kinds and the amount of replaced admixture are similar to those from the concrete. mortar model could be used as a prediction model of chemical resistance of concrete.

• Advances in concrete construction
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• v.4 no.2
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• pp.145-160
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• 2016

Marble is a metamorphic rock used widely in construction which increases amount of marble powder obtained from it. Marble powder is a waste product obtained from marble during its processing. Marble waste is high in calcium oxide content which is cementing property but it creates many environmental hazards too if left in environment or in water. In this research, partial replacement of cement and sand by waste marble powder (WMP) has been investigated. Seven concrete mixtures were prepared for this investigation by partially replacing cement, sand with WMP at proportions of 0%, 10% and 15% by weight separately and in combined form. To determine compressive strength, flexural strength and split tensile strength of concrete made with waste marble powder, the samples at the curing ages of 7, 28 and 90 days was recorded. Different tests of durability were applied on samples like ultrasonic pulse wave test, absorption and sorptivity. For further investigation all the results were compared and noticed that WMP has shown good results and enhancing mechanical properties of concrete mix on partially replacing with sand and cement in set proportions. Moreover, it will solve the problem of environmental health hazard.