• Korean Journal of Agricultural Science
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• v.6 no.2
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• pp.185-191
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• 1979

Compressive and tensile strengths of commonly being used mortar and mortar specially hardened by adding 1%, 2% and 3% of $CaCl_2$ were compared under the different mixing ratio of mortar and ages to investigate the effect of $CaCl_2$ which is being used as a promotor for coagulation and hardness, on the strength of mortar. The results obtained were as follows: 1. The compressive strength of mortar hardened by addition of $CaCl_2$ was higher than that of commonly being used mortar. The highest compressive strength of mortar was obtained when 2% of $CaCl_2$ were added. 2. The tensile strength of mortar, which was made by adding $CaCl_2$ and aged for seven days, was higher than that of commonly being used mortar. The highest tensile strength of mortar was obtained when 1% of $CaCl_2$ was added and aged for 28 days. And the tensile strength of mortar with 2% of $CaCl_2$ was lower than that of commonly being used mortar. 3. When the amount of $CaCl_2$ added was higher than 3%, the mortar was abruptly hardened and thereby occurred crack was considered lowering strength of mortar. 4. The rich mix was effective for the increasing the compressive and tensile strength before seven days of age and less effective after seven days of age. Therefore, the addition of one to two per cent of $CaCl_2$ would be effective for promoting initial strength of mortar during winter season.

• Journal of the Korea Concrete Institute
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• v.16 no.6 s.84
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• pp.875-881
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• 2004

The quality of recycled aggregate is affected by original concrete strength and the manufacturing process of recycled aggregates. In this study, the porosity of old and new mortar, and the compressive strength of concrete were investigated to examine the influence of recycled aggregate on the concrete. Six kinds of recycled coarse aggregates were produced from concrete blocks of differing strength levels (A:60. 1MPa, B:41.7MPa, C:25.5MPa). Original concrete strength and the bond mortar of recycled aggregate influences the pore structures of both old and new mortar. The pore size distribution of old mortar was found to be greatly affected by age, and the reduction of the porosity of bond mortar on low strength recycled aggregate increased at a greater rate than that of bond mortar on high strength recycled aggregate. The pore size distribution of new mortar in recycled aggregate concrete changed in comparison with that of new mortar in virgin aggregate concrete. The total porosity of new mortar using B level recycled aggregates was smaller than that of new mortar with A, and C level recycled aggregates. Moreover, the compressive strength of recycled aggregate concrete was found to have been affected by original concrete strength. The compressive strength of concrete only changed slightly in the porosity of new mortar over $15\%$, but increased rapidly in the porosity of new mortar fewer than $15\%$.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2014.11a
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• pp.158-159
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• 2014

In general, the shrinkage occurring in the floor mortar is large the influence by the dry shrinkage. In order to reduce the cracks occurring in the floor mortar, studies of physical methods are often performed, but these methods is difficult to prevent cracking of the floor mortar essentially. Therefore, in this study, the dry shrinkage properties of floor mortar of gypsum and red clay type using alpha-hemihydrate gypsum had been evaluated. The experimental variables were cement mortar(CM), gypsum mortar(GM), red-clay mortar(RM), the evaluation items was conducted experiment to evaluate the setting time, the compressive strength, drying shrinkage cracks, the dry shrinkage. As a result, it was confirmed that condensation time of GM is shorter that that of CM, and GM satisfied the compressive strength of the floor mortar standard. Also shrinkage deformation of GM reduced more than the CM.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2013.05a
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• pp.305-307
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• 2013

In this paper, we test and evaluate in terms of workability the epoxy resin mortar and the EVA powder resin mortar used on the concrete structures. The initial viscosity of the epoxy resin mortar is lower than the EVA powder mortar, but after 20 minutes work can not be rapidly increased to 40 minutes. In the other hand, the EVA powder resin mortar is able to measure of viscosity for the past 40 minutes. In the flow test for evaluate workability, the flow of the epoxy resin mortar is rapidly decreased from 230 to 100 in the 90 minutes, but the flow of the EVA powder resin mortar is reduced to 198 to 175 that there is no significant change. In the coverage test of the pinhole on the concrete surface, the EVA powder mortar appears coverage in the all pinhole size but the epoxy resin mortar is not concealed from 2mm pinhole size.

• Journal of the Korea Concrete Institute
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• v.11 no.6
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• pp.121-128
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• 1999

The SHO PATCH System Mortar is a mortar shotcreting system which uses fairly small machine and equipment, and is applied for shotcrete tunnel linings, in particular for small bore tunnels of aqueducts by the TBM(Tunnel Boring Machine) method, and for reparing tunnels suffering from spring water and deterioration. This study shows the characteristics of the new mortar shotcreting system, the SHOT PATCh System Mortar, which exhibits excellent shotcrete performance.

• Proceedings of the Korea Concrete Institute Conference
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• 1993.04a
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• pp.89-92
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• 1993

This paper deals with the effect of siliceous slurry coatings on mortar microstructure under a damp environment. For estimation on effect of siliceous slurry coating, microstructure of coated mortar was observed through SEM. Crystal production in mivrosturcture of coated mortar was periodically increased, and more produced in mortar of high water-cement ratios. And they were generated mainly in mortar ranging from the surface to the inside about 2.5 or 3mm deep.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 1998.10a
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• pp.107-112
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• 1998

The objective of this study was to develop a polymer mortar defensive block with high strength and durability using unsaturated polyester resin to complement defects of conventional cement mortar defensive block. Physical and mechanical properties of the polymer mortar defensive block were also investigated. Low absorptivity, high impact strength, and great bending strength of the polymer mortar defensive block was compared with those of the conventional cement defensive block. In conclusion, the polymer mortar defensive block is excellent and useful as industrial products for erosion control works.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.10c
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• pp.76-81
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• 1998

The physical properties of cement sludge treated with hydrofluosilicic acid were investigated. The compressive strength of cement mortar substituted cement sludge was decreased than that of OPC(ordinary portland cement) mortar. Cement sludge, for improving its physical properties, was treated with hydrofluosilicic acid. And compressive strength of cement mortar substituted TCS was greatly improved than that of OPC mortar. Particularly, cement mortar substituted TCS had the higher value in water-proofness than of OPC.

• Proceedings of the Korea Concrete Institute Conference
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• 1995.04a
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• pp.100-105
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• 1995

The aim of this study is to developed water proofing properties of cement mortar this study the effect of mix proportion on the basic characteristics of cement mortar was investigated. Also water absorption and permeability properties of mortar using several admixtures were tested. from this results, Physical properties of mortar is improved by using the sand witch has a broad particle size distribution. Also the sililca alumina powder is effective for decreasing the water permeability of mortar and zinc stearate is in creasing the water repellence property.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.65-68
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• 2006

In this study, comparison of setting time, compressive strength, watertightness and durability of between reference mortar with mortar using waterproof admixtures based on natural inorganic minerals. Test results shows that waterproof admixtures does not change setting time of mortar, but strongly improve compressive strength, permeability, absorption and durability of mortar. Especially early strength of mortar increased about 40% of reference.