• Journal of the Korea Institute of Building Construction
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• v.3 no.3
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• pp.107-112
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• 2003

This study is to investigate the properties of concrete with crushed sand on site and to propose a quality guideline for its use as artificial sand and concrete. From our experimental result in laboratory and site, we found that demand water of concrete with crushed sand for target slump increased by 18kg/m3 compared to mixed sand and l8kg/m3 compared to sea sand respectively. The compressive strength increased by around 3∼6% when compared to concrete with sea sand. Accordingly, our study showed that the combined sand mixed with sea sand would be desirable to obtain workability and strength of concrete including dry shrinkage and bleeding test. Furthermore, the optimal replacement percentage of crushed sand was 50% with sea sand. As such, crushed sand would be sufficient as fine aggregate for concrete in terms of economic efficiency and quality. Crushed sand, on the other hand can only be used as fine aggregate when VFS(Very Fine Sand) is below 3.5 percentage of weight of sand and particle shape is above 55 percentage. Also, the particle shape and microsand passing NO.200 sieve should continually be improved to increase workability of concrete on site.

• Advances in concrete construction
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• v.16 no.4
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• pp.177-188
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• 2023

In the context of the shortage of river sand, two types of manufactured sand (MS) were used to partially replace river sand (RS) to design manufactured sand concrete (MSC). A total of 81 specimens were designed for uniaxial compression test and beam flexure test. Two parameters were considered in the tests, including the types of MS (i.e. limestone manufactured sand (LMS), pebble manufactured sand (PMS)) and the MS replacement percentage (i.e., 0%, 25%, 50%, 75%, 100%). The stress-strain curves of MSC were obtained. The effects of these parameters on the compressive strength, elastic modulus, peak strain, toughness and flexural strength were discussed. Additionally, the sensitivity of particle size distributions to the performance of MSC was evaluated based on the grey correlation analysis. The results showed that compared with river sand concrete (RSC), the rising slope of the stress-strain curves of limestone manufactured sand concrete (LMSC) and pebble manufactured sand concrete (PMSC) were higher, the descending phrase of LMSC were gentle but that of PMSC showed an opposite trend. The physical and mechanical properties of MSC were affected by the MS replacement percentage except the compressive strength of PMSC. When the replacement percentage of LMS and PMS were 50% and 25% respectively, the corresponding performances of LMSC and PMSC were better. In generally, when the replacement percentage of LMS and PMS were same, the comprehensive performance of LMSC were better than that of PMSC. The constitutive model and the equations for mechanical properties were proposed. The influence of particle ranging from 0.15 mm to 0 mm on the performance of MSC was lower than particle ranging from 4.75 mm to 0.15 mm but this influence should not be ignored.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.10a
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• pp.342-349
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• 1998

The objective of this study is to investigate the characteristic change of antiwashout underwater concrete with variation of blend ratio of sea sand and fine aggregate percentage through experimental researches. According to the experiments results, when sea sand are mixed in antiwashout underwater concrete mixture by about 40% per total fine aggregate, in fine aggregate percentage of 40%, it is found that the flowability fit and the compressive strength is higher others.

• Proceedings of the Korea Concrete Institute Conference
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• 1996.10a
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• pp.10-16
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• 1996

This study is aimed for investigating a decision of the saturated surface dry of crushed stone sand and measuring the moisture with increasing percentage of VFS(Very Fine Sand) replacement each crushed stone sand. The results indicated that moisture of crushed stone sand is generally increased with increasing percentage of VFS replacement and the rate of increase of moisture is about 30% every time that VFS replacement increases 3.5%. Also the saturated surface dry for crushed stone sane is proposed as a point of time where shape of flow-cone first slumps in this paper.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.04a
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• pp.147-152
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• 1998

This study is to investigate the application of concrete with crushed sand on site. As a result, it is showed that the combined sand mixed with sea sand is very desirable for obtaining workability and strength of concrete, and the optimal replacement percentage of crushed sand is 50% with sea sand. After all, the crushed sand could be sufficiently used as a fine aggregate for concrete in the aspect of economical efficiency and quality, but the particle shape and microsand passing No.200 sieve should be firstly improved for increasing workability of concrete on site.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.04a
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• pp.227-230
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• 1998

The void ratio, continuous void ratio, coefficient of permeability, compressive strength and tensile strength were considered according to the EAF(Electric Arc Furnace) slag replacement and sand percentage in permeable concrete used with EAF slag as aggregate. The sand percentage was directly proportional to the permeable coefficient, but inversely proportional to the compressive strength. When the compressive strength and coefficient of permeability were 230 kg/$\textrm{cm}^2$ and 1$\times$$10^{-1}$ cm/sec, the useful sand percentage was 8%. When the EAF slag replacement was 25%, the coefficient of permeability was the most low and compressive strength was the most high.

• Geomechanics and Engineering
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• v.10 no.2
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• pp.155-174
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• 2016

A total of 104 laboratory model tests on a square footing subjected to eccentrically inclined loads supported by sand reinforced with randomly distributed polypropylene fibers were conducted in order to compare the results with those obtained from unreinforced sand and with each other. For conducting the model tests, uniform sand was compacted in a test box at one particular relative density of compaction. The effect of percentage of reinforcement used, thickness of the reinforced layer, angle of inclination of load to vertical and eccentricity of load applied on various prominent factors such as ultimate load, vertical settlement, horizontal deformation and tilt were investigated. An improvement in ultimate load, vertical settlement, horizontal deformation and tilt of foundation was observed with an increase in the percentage of fibers used and thickness of reinforced sand layer under different inclinations and eccentricities of load. A statistical model using non-linear regression analysis based on present experimental data for predicting the vertical settlement ($s_p$), horizontal deformation ($hd_p$) and tilt ($t_p$) of square footing on reinforced sand at any load applied was done where the dependent variable was predicted settlement ($s_p$), horizontal deformation ($hd_p$) and tilt ($t_p$) respectively.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.383-386
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• 2005

This paper is to investigate the effect of W/B, blend ratio of crushed sand with sea sand on fluidity and strength properties of high strength concrete utilizing crushed sand. W/B set up 0.25, 0.30, 0.35 and the blend ratio of crushed sand with sea sand set up 0:100, 30:70, 50:50, 70:30, 100:0 The results of this study are summarized as the follows; 1) The increase of the blend rate of crushed sand, affected on the enhancement of flow, the increase of dosage of SP and water content, but the decrease S/a 2) Compressive strength is increased when crushed sand $30\~70\%$ was replaced with sea sand. 3) The optimal replacement percentage of crushed sand is $50\%$ with sea sand.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.1A
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• pp.229-236
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• 2006

Recently, the use of crushed sand produced by the crushing of stone is continuously increasing to reach an utilization rate of about 20% of the whole fine aggregates that is foreseen to grow larger in the future. However, the lack of recognition concerning quality during the production of crushed sand results in the use of crushed sand that do not satisfy the KS F 2527 standard during the manufacture of concrete. And, studies investigating the effects of such crushed sand on concrete are still neglected. Therefore, this study intends to provide data that can be exploited for concrete using crushed sand through the analysis of the effects of the grain shape of crushed sand on the quality of concrete. Results revealed problems in the workability, air entraining and durability for a value of 53% for the solid volume percentage for shape determination specified by the current KS F 2527. Analysis showed that the adjustment of the solid volume percentage for shape determination from the currently specified 53% to 55% will improve the quality of concrete using crushed sand in high strength concrete particularly.

• Journal of the Korea Concrete Institute
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• v.11 no.5
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• pp.51-60
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• 1999

When placed under water, concrete is diluted with separating cementitious material and as a result the quality of concrete becomes poor. So as to solve the problem, underwater concrete is increasingly used for the construction and repair of the concrete structure under water. In this paper, 4 kinds of antiwashout admixtures and varying sand percentages were chosen to measure the suspended solids, pH, air contents, setting time and compressive strength of underwater concrete, and they meet "Standard for antiwashout admixture used for concrete". When sand percentage is 43%, the fluidity and filling of underwater concrete are superior to the others.he others.