• Proceedings of the Korean Institute of Building Construction Conference
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• 2006.11a
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• pp.53-56
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• 2006

The objection of this study is to investigate the properties of cement mortar with the kinds and addition of expansive additives. 3 kinds of expansive additives produced in our country and 0, 5, 10, 15, 20% of ratio of addition rate are selected for this experiment. According to experimental results, flow of cement mortar with expansive additives is nearly same with flow of plain mortar and compressive strength, tensile strength, bend strength of cement mortar with expansive additives at 28 days is higher than that of plain mortar.

• Biotechnology and Bioprocess Engineering:BBE
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• v.6 no.2
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• pp.112-116
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• 2001

The production of extracellular polysaccharide, EPS WN9, from Paenibacillus sp. and its suitability as a viscosity modifying admixture for cement mortar mixing were investigated. After 48h culture in an optimized medium, cell growth and EPS production were 1.2g/L and 4.0g/L, respectively. By adding EPS WN9 to mortar, it was possible to prepare a homogeneous mortar without material segregation and excess air entrapment. The optimal amount of EPS addition to mortar found to be 0.02 to 0.05%(w/w) of the cement used. Increasing the dosage of EPS WN9 from 0 to 0.05%(w/w) resulted in a setting retardation of 0.14h to 0.8h and an increase in the compressive strength of mortar of 10 to 20%.

• Journal of the Korea Institute of Building Construction
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• v.11 no.6
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• pp.587-596
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• 2011

Ultra rapid-hardening cement is widely used for latex-modified mortar and concrete as repair and finishing material during urgent work. The purpose of this study is to evaluate the improvements in strength made to SBR cement mortars by the adding of various admixtures and by the use of different curing methods. SBR cement mortar was prepared with various polymer-cement ratios, curing conditions and admixture contents, and tested for flow, flexural and compressive strengths. From the test results, it was determined that the flow of SBR cement mortar increased with an increase in the polymer-cement ratio, and the water reducing ratio also increased. The strength of cement mortar is improved by using SBR emulsion, and is strengthened by adding metakaoline. The strength of SBR cement mortar cured in standard conditions was increased with an increase in the polymer-cement ratio, and attained the maximum strengths at polymer-cement ratios of 15 % and 10 %, respectively. The maximum strengths of SBR cement mortar are about 1.8 and 1.3 times the strengths of plain mortar, respectively. In this study, it is confirmed that the polymer-cement ratio and curing method are important factors for improving the strengths of rapid-hardening SBR cement mortar.

• Proceedings of the Korea Concrete Institute Conference
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• 1995.04a
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• pp.142-147
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• 1995

In this study, styrene-maleic anhydride copolymer (SMA) was synthesized from styrene and maleic anhydride and further reacted with sulfuric acid to obtain water-soluble SMA and the flow and strength tests of cement mortar mixed with copolymers were carried out to evaluate the capability of copolymers as high range water reducer for the concrete. It was found from flow experiment that the fluidity of cement mortar mixed with sulfonated SMA (SSMA) was larger than that miced with aminophenol-substituted SSMA (SmSMA). The decreasing rate of the flow of cement mortar mixed with SSMA and SmSMA was decreasing rate of the flow of cement mortar mixed with SSMA and SmSMA was significantly lower than that mixed with naphthalene condensate (NSC). The compressive strength of the hardened cement mortars containing 0.5% copolymers after 28 days curing was examined. The compressive strength of hardened cement mortar containing SSMA and SmSMA was increased up to 32% and 13%, respectively, when compared to the plain. As the results, the copolymers (SSMA and SmSMA) used in this study are greatly expected as a good high range water reducers for the concrete.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.1273-1278
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• 2007

The cement-asphalt mortar is a mixture of cement and asphalt emulsion, and is utilized as a underpouring materials for the railway track which is used to fill under slab panel space so as to provide a stabilized track support and a tool for reduction of noise and vibration. To increase the workability of grouting, this study investigates the effect of temperature on cement-asphalt mortar by analyzing its physical and mechanical properties before/after hardening according to the temperature (10, 15, 20, 25, $30^{\circ}C$). According to the test results, it is found that as for the physical property of fresh cement-asphalt mortar the more mixture temperature become higher or lower, the more fluidity become worse. But by increasing reducing agent amount and its unit quantity, the required fluidity is met. The compressive strength as physical property of hardened cement-asphalt mortar become lower when temperature is lower but taking it by and large the physical properties of cement-asphalt mortar before/after hardening aren't so affected by temperature and well satisfy the requirement. And it has proved that rate of expansion and freezing and thawing resistance aren't affected by temperature.

• Cement Symposium
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• no.22
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• pp.162-169
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• 1994

• Magazine of the Korea Concrete Institute
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• v.8 no.6
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• pp.163-172
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• 1996

Recently, the disposal of used vehicle tires is a big social problem because the amount of used vehicle tires has been increased with development of' automobile industry. Many researches have been made on the recycling of used vehicle tires in the various fields of industry as well as construction industry. When the crumb rubber made of vehicle tires is mixed in cement concrete and mortar, it is indicated that the adhesive strength of interface between the crumb rubber and cement hydrates is very low. The purpose of this study is to improve the fundamental properties by increasing of the adhesion strength of styrene-butadiene rubber(SF3R) latex coated crumb rubber in ; cement mortar. SBR-modified mortar using crumb rubber is also tested as the same method. From the test results, the cement mortar using SBR latex coated crumb rubber have a good fundamental properties compared with that using uncoated crumb rubber. The mechanical properties of SBR-modified mortar using crumb rubber with polymer-cement ratios of 10% are also improved.

• Advances in materials Research
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• v.11 no.2
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• pp.121-146
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• 2022

In the recent years, the use of agricultural waste in green cement mortar and concrete production has attracted considerable attention because of potential saving in the large areas of landfills and potential enhancement on the performance of mortar. In this research, microparticles of palm oil fuel ash (POFA) obtained from a multistage thermal and mechanical treatment processes of raw POFA originating from palm oil mill was utilized as a pozzolanic material to produce high-performance cement mortar (HPCM). POFA was used as a partial replacement material to ordinary Portland cement (OPC) at replacement levels of 0, 5, 10, 15, 20, 25, 30, 35, 40% by volume. Sand with particle size smaller than 300 ㎛ was used to enhance the performance of the HPCM. The HPCM mixes were tested for workability, compressive strength, ultrasonic pulse velocity (UPV), porosity and absorption. The results portray that the incorporation of micro POFA in HPCMs led to a slight reduction in the compressive strength. At 40% replacement level, the compressive strength was 87.4 MPa at 28 days which is suitable for many high strength applications. Although adding POFA to the cement mixtures harmed the absorption and porosity, those properties were very low at 3.4% and 11.5% respectively at a 40% POFA replacement ratio and after 28 days of curing. The HPCM mixtures containing POFA exhibited greater increase in strength and UPV as well as greater reduction in absorption and porosity than the control OPC mortar from 7 to 28 days of curing age, as a result of the pozzolanic reaction of POFA. Micro POFA with finely graded sand resulted in a dense and high strength cement mortar due to the pozzolanic reaction and increased packing effect. Therefore, it is demonstrated that the POFA could be used with high replacement ratios as a pozzolanic material to produce HPCM.

• Journal of the Korea Institute of Building Construction
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• v.21 no.1
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• pp.11-19
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• 2021

The aim of the research is providing a fundamental data on quality and constructability of direct tile setting method depending on various cement to sand ratio for tiling dry cement mortar. A large number of tile setting failures reported is related with the cement mortar and its construction for tiling. Because of different materials of tiles, the properties of tiling dry cement mortar, an adhesive for tiling, can influence on quality and constructability of tiling differently. Practically, the easiest way of controlling the properties of the tiling dry cement mortar is to control the proportion of cement and sand. Hence, in this research, sand to cement ratio (S/C) was controlled. Since there is no standarized method on evaluating performance of dry cement mortar for tiling, a several sensory evaluation methods were suggested and executed. According to the experiments conducted in this research, the adhesive performance of cement mortar for tiles can be different depending on the sides such as tile and substrate. Additionally, depending on S/C, finishability, initial adhesive performance, and tile shifting resistance can be changed for ceramic tile. Therefore, under the conditions of this research, about 5 of S/C can be recommended for appropriate performace of tiling dry cement mortar.

• Korean Journal of Agricultural Science
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• v.8 no.2
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• pp.185-194
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• 1981

This study was carried out to determine the effect of accelerated curing on the strength of standard sand mortar and briquette ash mortar. The standard sand mortars and the briquette ash mortars made by mixture of the standard sand:cement and the briquette ash:cement at the ratio of 2 : 1, 3: 1 and 4 : 1, respectively, were cured at 4 different temperature of $20^{\circ}C$, $60^{\circ}C$, $80^{\circ}C$ and $100^{\circ}C$. The compression and tensil strength of mortars were measured at ${\sigma}_3$, ${\sigma}_7$, ${\sigma}_28$. The results obtained are summarized as follows; 1. At each age of curing and each curing temperature, the compression and tensile strength of the mortars made by the mixture of cement and standard sand was significantly higher than that of the mortars made by the mixture of cement and briquette ash. But the increasing rate of strength in compression and tension was significantly higher at the mortars of cement and briquette ash than those of cement and standard sand. 2. The strength of mortars which showed lower strength than Korean Standard at ordinary curing temperature was significantly increased and showed higher value than Korean Standard by the accelerated curing at high temperature. The increasing rate of strength by the accelerated curing was higher at the mortars containing less amount of cement than those containing more cement. The hardening of the mortars containing less amount of cement was significantly promoted by the accelerated curing in high temperature. 3. When the briquette ash was substituted for the materials of cement mortar, decline of the mortar strength is. unavoidable. But the enhancement of the mortar strength is still expected by the experimental results that the strength of cement-briquette ash mortar showed an increase of 137.6% by the accelerated curing at $60^{\circ}C$, 164.1% at $80^{\circ}C$ C and 183.8% at $100^{\circ}C$, respectively, compared with the strength of mortar cured at $20^{\circ}C$ for 28 days. 4. As the strength of cement briquette mortar is lower than that of cement standard sand mortar, the cement briquette ash mortar is expected to be increased in strength by the accelerated curing at high temperature. The cement briquette mortar is expected to be utilized to the production of secondary mortar goods or the constructions which need low strength of mortar.