• Advances in materials Research
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• v.11 no.4
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• pp.251-277
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• 2022

Disposal of industrial waste in cities where municipal authorities permitting higher floor area ratio coupled with increasing living standards, a lot of demolition waste is being generated. Its disposal is a challenge particularly in megacities where no landfills are available. The ever-increasing cost of building construction materials also necessitates consuming demolition wastes in a useful manner to save fresh natural raw materials. In the present work, the crushed waste glass is used in high-strength concrete as a partial replacement of fine aggregate. The control concrete of grade M60 was proportioned following BIS 10262-2009. The crushed waste glass has been used as a partial replacement with varying percentages of 10, 20, 30, and 40% by weight of fine aggregate. Experimental tests were carried on the fresh and hardened state of the concrete. The effect of crushed waste glass on the workability of the concrete has been investigated. Non-destructive tests, acid attack tests, compressive strength, split tensile strength, and X-ray diffraction analysis was carried out for the control concrete and concrete containing crushed waste glass after 7, 28, and 270 days of normal curing. The results show that for the same w/c ratio, the workability of concrete increases with increasing replaced crushed waste glass content. However, the decrease in compressive strength of the concrete after 28 days of normal curing and further after 28 days of acid attacks, up to 30% replacement level of fine aggregate by the crushed waste glass is insignificant.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.204-207
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• 2004

In this paper, mechanical properties of the high strength lightweight self-compacting concrete with simple mixed design method was investigated. Experimental tests were performed as such compressive strength, splitting tensile strength, modulus of elasticity and density of high strength lightweight self-compacting concrete. The 28 days compressive strength of high strength lightweight self-compacting concrete with the LC replacement ratio of $100\%$ reduces about $31\%$ but LF replacement ratio of $100\%$ increase about $20\%$ compared that of the control concrete. The structural efficiency of high strength lightweight self-compacting concrete increase with proportional to the replacement into of LF. The relationship between the splitting tensile strength and 28 days compressive strength can be represented by the equation $f_s=0.076f_{ck}+0.5582$. The modulus of elasticity was found to be lower than that of normal weight concrete, ranging form 24 to 33 GPa.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.11a
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• pp.269-272
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• 2003

This study is intended to investigate the properties of concrete using AE Water Reducing Agent of Early-Strength Type. According to the results, as for the replacing method of mineral admixture, setting time is shortened faster in order of replacement for fine aggregate, combination and replacement for cement, and when AE Water Reducing Agent of Early-Strength Type is used, it is shortened by about 4 hours, compared with normal AE Water Reducing Agent Compressive strength is lower in the case of replacement for fine aggregate, but higher in the other case than that of plain concrete. And When AE Water Reducing Agent of Early-Strength Type is used, early compressive strength is very high in comparison to normal AE Water Reducing Agent. Early strength development is very favorable by the use of AE Water Reducing Agent of Early-Strength Type regardless of the replacing method of mineral admixture at $20^{\circ}C$, but at $l0^{\circ}C$, it is effective for Early strength development that W/B is lowered to below 45%, BS of 20% is replaced for fine aggregate, and AE Water Reducing Agent of Early-Strength Type is used.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.741-744
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• 2003

In this study, the influence of chemical admixture on early strength development of concrete is discussed. According to the results, fluidity with variation of kinds of chemical admixture is lower in the case of acceleration type than in the case of normal type. Setting time of naphthalene acceleration type is shortened by I hour, and that of melamine is nearly same, but that of polycarbonic acid is somewhat retarded in comparison with that of naphthalene normal type. Early compressive strength gains 5MPa in about 18hours regardless of the kinds of chemical admixture. But as time elapses, compressive strength is higher in order of polycarbonic acid, naphthalene and melamine type. The relativity between compressive strength and the rebound value of P-type schmidt hammer is also favorable at early age, and compressive strength of 5MPa is estimated at the rebound value of 22.

• Proceedings of the Korea Concrete Institute Conference
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• 1995.04a
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• pp.8-13
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• 1995

High strength ready-miced concrete with delivering time of about 90 minutes is successfully produced at ready-mixed concrete plant and placed columns and retaining walls of a tall building without any problems. The design strength of the concrete is 450 kgf/$\textrm{cm}^2$ and the required average compressive strength is 540 kgf/$\textrm{cm}^2$ according to ACI 363R-84 report with assumed coefficient of variation of 12% For the producing of good quality concrete, many laboratary and field tests are carried out. As the results of this study, the slump loss of high strength concrete is largely influenced by kinds of superplasticizer. The measured pump pressure of high strength concrete with slump of 22cm is higher than that of normal strength concrete with slump of 18cm by about 20~30% The measured average 28-day compressive strength of the concrete is 551 kgf/$\textrm{cm}^2$ and the coefficient of variation is 2.3%

• Proceedings of the Korea Concrete Institute Conference
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• 1996.04a
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• pp.18-23
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• 1996

Since at least three-quarters of the volume of concrete is occupied by aggregate, it is not surprising that its quality is considerable importance. Not only may the aggregate limit the strength of concrete, as weak aggregate cannot porduce strong concrete, but the properties of aggregate greatly affect the durability and sructural performance of concrete. But, it is ture that aggregate strength is usually not a factor in normal concrete strength because the aggregate particle is several times stronger than the matrix and the transition zone in concrete. This study is to consider the influence the strength of concrete according to the kinds of aggregate, such as crushed river rocks, curshed rocks, high strength recycled aggregate, low strength recycled aggregate at water cement ratio 0.25. It is possible to concern the important of the mechanical role of aggegate for the high strength concrete.

• Proceedings of the Korea Concrete Institute Conference
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• 1992.04a
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• pp.53-58
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• 1992

This research is related to the experimental investigation of the inelastic behavior of R/C columns with high strength concrete. A total of eight specimens have been tested with different span ratios, steel reinforcements and load applications. Through tests bending moments were applied incrementally while axial forces being kept constantly at 80 tons. Careful observation were given to initial crack formation, crack patterns and propagation paths. Comparative studies have been made on the load carrying capacity for R/C columns with high strength concrete versus normal strength concrete.

• Korean Journal of Agricultural Science
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• v.24 no.2
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• pp.218-225
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• 1997

This study was performed to evaluate the physical and mechanical properties of surlightweight polymer concrete using synthetic lightweight aggregate. The following conclusions were drawn; 1. Unit weight was in the range of $810~970kgf/m^3$, the unit weights of those concrete were decreased 58~65% than that of the normal cement concrete. 2. The highest strength was achieved by $P_1$, it was increased 112% by compressive strength, 378% by bending strength and 290% by tensile strength than that of the normal cement concrete, respectively. 3. Ultrasonic pulse velocity was in the range of 2,206~2,595m/s, which was low showed compared to that of the normal cement concrete. 4. Durability of surlightweight polymer concrete was superior to that of the normal cement concrete. 5. Compressive, tensile and bending strength were largely showed with the increase of unit weight. But, ultrasonic pulse velocity was low showed with the increase of unit weight.

• Magazine of the Korea Concrete Institute
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• v.8 no.6
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• pp.173-182
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• 1996

An experimental research was carried out to investigate the effect of thc compressive strength of concrete on the stirrup effectiveness in shear behavior of concrete beams. For this purpose. total 24 beams of section dimension of $300{\times}600mm$ were tested: 4 specimens without web reinforcement and 20 specimens with web reinforcement in the form of vertical stirrups. Main variables were two levels(norma1 and high strength) of the compressive strength of concrete and six types of t h e shear rcinfor.cement ratios. Prior to experiment, for given sections and assumed material constants, the reference shear reinforcement ratio(${\rho}_vACI$) which leads to the flexure failure using the provisions of the ACI Building Code(AC1 318-95) was calculated. and the shear reinforcement ratios were relatively selected from the value of ${\rho}_vACI$. From test results, it was shown that thc safety factor of ACI eyuation for p1,ediction of shear strength was decreased with increasing the compressive strength of concrete in beams without stirrups. However. it was observed that as the amount of' stirrup is increased, the safety factor for high strength conci,ete beams with high stirrup ratio is ensured more than that for normal strength concrete beams. Therefore i t appears that the stirrup effectiveness of high strength concrete beams is greater than that of normal strength concrete beams.

• Structural Engineering and Mechanics
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• v.58 no.6
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• pp.989-999
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• 2016

Moist curing of concrete is a time consuming procedure. It takes minimum 28 days of curing to obtain the characteristic strength of concrete. However, under certain situations such as shortage of time, weather conditions, on the spot changes in project and speedy construction, waiting for entire curing period becomes unaffordable. This situation demands early strength of concrete which can be met using accelerated curing methods. It becomes necessary to obtain early strength of concrete rather than waiting for entire period of curing which proves to be uneconomical. In India, accelerated curing methods are used to arrive upon the actual strength by resorting to the equations suggested by Bureau of Indian Standards' (BIS). However, it has been observed that the results obtained using above equations are exaggerated. In the present experimental investigations, the results of the accelerated compressive strength of the concrete are used to develop the regression models for predicting the short term and long term compressive strength of concrete. The proposed regression models show better agreement with the actual compressive strength than the existing model suggested by BIS specification.