• International Journal of Concrete Structures and Materials
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• v.4 no.1
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• pp.3-8
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• 2010

This paper present the results of investigation on the use of rice husk ash as a partial substitute for cement in construction. One hundred and eighty specimens of concrete cubes were cast. 0, 5, 10, 15, and 20% partial replacement of cement with rice husk ash were carried at 1:2:4 mixes by weight with 0.60, 0.65, 0.70 water/cement ratio. The results indicated that compressive strengths of cubes at 0.6, water/cement were higher than 0.65 and 0.70. Also 5% partial replacement cement with rice husk ash at $28^{th}$ day average compressive strength value of $25.4\;N/mm^2$ compared well with 0% partial replacement of cement with rice husk ash of $26.28\;N/mm^2$. This shows that at 5% partial replacement of cement with rice husk ash can be used for structural concrete and at 15% replacement or more it can be used for non - structural construction works or light weight concrete construction. The cost analysis shows substantial amount of savings for the country.

• Resources Recycling
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• v.12 no.5
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• pp.23-28
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• 2003

Converter slag was reduced and modified with the addition of 5~10 weight percent of $SiO_2$, $Al_2O_3$ and $SiO_2+Al_2O_3$. which was water quenched and used as a cement additives. Additive was mixed from 10 to 30 weight percent with ordinary portland cement and made 9 kinds of mixed cement. Compressive strength of mixed cement mortar was tested md compared with com pressive strength of ordinary portland cement mortar. Effect of hydration reaction on the compressive strength of cement mortar was investigated by means of x-ray diffraction and scanning electron microscopy.

• Journal of the Korea Concrete Institute
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• v.11 no.4
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• pp.21-29
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• 1999

In this study, an experiment was performed to analyze the influence of water-cement ratio on the fundamental characteristics of antiwashout underwater concrete using blended sand (sea sand:river sand = 1:1). The water-cement ratio (45%, 50%, 55%, 60%), andtiwashout underwater agent contents (0.82%, 1.00%, 1.14% of water contents per unit volume of concrete), and superplasticizer contents (1.5%, 2.0%, 2.5% of cement contents per unit volume of concrete) were chosen as the experimental parameters. The experimental results show that the underwater segregation resistance, unit weight of hardening concrete and compressive strength were increased as the water-cement ratio decreased and as the antiwashout underwater agent contents increased. On the other hand, the flowability(slump flow) was increased to the 55% of the increase of water-cement ratio, however, it was decreased at the ratio of 60%. From this study, the antiwashout underwater concrete can potentially be used as a materials underwater work of ocean if the water-cement ratio and chemical admixture contents for the suitable balance between cost and performance are properly selected.

• Computers and Concrete
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• v.10 no.6
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• pp.649-662
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• 2012

This paper presents the results of an investigation on the compressive strength and weight loss of mortars containing three types of fillers as cement replacements; Limestone Filler (LF), Silica Fume (SF) and Trass (TR), subjected to elevated temperatures including $400^{\circ}C$, $600^{\circ}C$, $800^{\circ}C$ and $1000^{\circ}C$. Results indicate that addition of TR to blended cements, compared to SF addition, leads to higher compressive strength and lower weight loss at elevated temperatures. In order to model the influence of the different parameters on the compressive strength and the weight loss of specimens, artificial neural networks (ANNs) were adopted. Different diagrams were plotted based on the predictions of the most accurate networks to study the effects of temperature, different fillers and cement content on the target properties. In addition to the impressive RMSE and $R^2$ values of the best networks, the data used as the input for the prediction plots were chosen within the range of the data introduced to the networks in the training phase. Therefore, the prediction plots could be considered reliable to perform the parametric study.

• Advances in concrete construction
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• v.11 no.2
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• pp.151-161
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• 2021

The major shortcoming of concrete in most of the applications is its high self-weight and thermal conductivity. The emerging trend to overcome these shortcomings is the use of foam-concrete, which is a lightweight concrete consisting of cement, filler, water and a foaming agent. This study aims at the development of a cost-effective high-volume fly-ash foam-concrete insulation wall cladding for existing buildings using natural fiber like rice straw in different proportions. The paper reports the results of systematic studies on various mechanical, acoustic, thermal and durability properties of foam-concrete with and without replacement of cement by fly-ash. Fly-ash replaces 60 percent by weight of cement in foam-concrete. The water-solid ratio of 0.3, the filler ratio of 1:1 by weight, and the density of 1100 kg/㎥ (approx.) are fixed for all the mixes. Rice straw at 1%, 3% and 5% by weight of cement was added to improve the thermal and acoustic efficiency. From the investigations, it was inferred that the strength properties were increased with fly-ash replacement up to 1% rice straw addition. In furtherance, addition of rice straw and fly-ash resulted in improved acoustic and thermal properties.

• Magazine of the Korea Concrete Institute
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• v.7 no.3
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• pp.149-155
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• 1995

An experimental study was carried out to investigate the strength implovlng effect of stone dust in no fines concrete. The cement aggregate ratios of 1:6, 1:8 and 1:10 and several water-cemment ratios between 30% and 56% were chosen for the mix design of no-fines concrete. For the no-fines concrete with stone dust, the weight ratio of cement to stone dust 1:1 was adopted and super plasticizer, 1.5% of cement in weight, was used to obtain proper and workable state of concrete. The compressive and tensile strength test were performed and the results for the different mix designs were compared with each other. The results show that the compressive strength of no-fines concrete can be improved by 38% and the tensile strength by 17%~72% for the same w/c, when the same weight of stone dust as cement is mixed together.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.1029-1034
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• 2001

The purpose of this research is to develop rapid setting cement latex modified concrete (RSLMC) which will be used to overlay bridge deck for maintaining and repairing. The main experimental variables were the types of rapid setting cement and variation of latex and antifoam agent contents were selected as admixture factor, then the properties of workability and strength development and durability properties were investigated. The results of this study show that latex content give increment of a slump due to surface tension in polymer particles and reduce unit weight of water for preservation of workability. In addition, When no and 1.6~3.2% antifoam agent were mixed, 8%, 2.0~3.8% were respectively obtained. An increasing the amount of latex produced concrete with increased flexural strength, but with slightly lower compressive strength. Rapid chloride permeability and freezing-thawing test carried out. As a results, according to increment of containing ratio antifoamer, strength of RSLMC increase, permeability showed lower value than ignorable 100 coulombs. Also, in the case of more than antifoamer 1.6%, the relativity dynamic modulus is mantained more than 90%, but in case of 0, 5%, it decrease. In consequence, with the view of strength and workability of RSLMC, it is considered that appropriate content ratio of antifoam agent and latex solid are respectively 1.6% by latex weight, 15% by cement weight.

• The Korean Journal of Ceramics
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• v.6 no.3
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• pp.318-321
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• 2000

Most compressive strengths commonly used in the construction field are in a range of 240 to 300 kgf/$\textrm{cm}^2$ at 28 days. To get this rage of strengths, however, high-flowing concrete requires cementitious binders more than 400 to 450 kg/$\textrm{cm}^2$ for preventing segregation and sedimentation of aggregates. This amount of cementitious binder generates a large emission of excessive hydration heat, which may consequently induce harmful cracks in concrete structure. In order to reduce excessive hydration heat, thus, this paper aims at fabricating a high-flowing concrete under the condition that cement content is kept as low as 350kg/$\textrm{cm}^3$ by using viscose agents. In a parametric study, effects of cement types such as a ternary blended cement and Type V on he physical characteristics of high-flowing concrete were evaluated. In addition, the influence of viscosity was also investigated by applying two different viscose agents, one in a range of 6,000 to 10,000 cps and the others of 10,000 to 14,000 cps. In terms of chemical admixtures used in concrete mixture, the superplasticizer was Sulfonated Melamine-Formaldehyde Condensate with about 30,000 of molecular weight, and main component of viscose agent was HPMC (Hydroxy Propyl Methyl Cellulose). Slump flow was fixed at 50cm with different dosages of superplasticizer in weight.

• Journal of The Korean Society of Agricultural Engineers
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• v.54 no.6
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• pp.159-167
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• 2012

In the present study, an investigation has been made on the application of cement-bentonite soil mixtures as the countermeasure against leachate produced by buried animal carcasses. For this purpose, the strength characteristics of the cement-bentonite soil mixtures mixed with geotextile and metakaolin. After the mixtures with different contents of the cement (0 %, 10 %), bentonite (0 %, 5 %, 10 %, 15 %, 20 %), and weathered soil (100 %, 95 %, 90 %, 85 %, 80 %) were prepared, metakaolin and geotextile were added with different contents (metakaolin : 0 %, 5 %, 10 %, 15 %, 20 % of the cement weight; geotextile : 0 %, 0.5 %, 1 %, 1.5 %, 2 %). Experimental results suggested that the early strength of the mixture increases due to the pore filling, the hydration acceleration, and the pozzolan reaction when metakaolin of 5~10 % of the cement weight was added. In addition, the compressive strength increase when 0.5~1 % geotextile contents were added, and the above these contents, the rate of strength increase was gradually decreased because of the fibrous tangles.

• Proceedings of the Korea Concrete Institute Conference
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• 1996.04a
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• pp.166-171
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• 1996

This study examines whether the raw diatomaceous rock, after thermally activated for converting into a pozzolanic form, can improve cement quality(i.e., compressive strength) of the cement-mortar. The diatomaceous rock, heat-treated at 75$0^{\circ}C$ for 30minutes as an optimum pozzolanic form was mixed with OPC(Ordinary Portland Cement) on a weight basis from 0, 2.5, 5.0, 10, 20, 40%. The cement quality was then assessed by the compressive strength and analysis of XRD(S-Ray Diffraction) and SEM(Scanning Electron Microscope).