• Proceedings of the Korean Institute of Building Construction Conference
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• 2014.11a
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• pp.135-136
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• 2014

In this study, the experimental study on the early age compressive strength of cement mortar using anti freezer and hardening accelerator at low temperature was conducted. For this study, all of materials for experiment were kept in a low temperature for 24 hours before mortar mixing. After mortar curing at low temperature, compressive strength was measured at the early ages. Furthermore, properties of hardened cement material was analysed using TG-DTA and MIP.

• Journal of the Korea Concrete Institute
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• v.28 no.6
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• pp.665-672
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• 2016

This study is conducted to investigate the effect of phase change materials (PCM) on hydration heat and strength characteristics of cement mortar. Two types of Barium and Strontium-based PCMs were used in this study and the addition ratio of each PCM to the cement mortar ranged from 1% to 5% by cement weight. Flow test, semi-adiabatic temperature rise test, compressive strength and flexural strength test were carried out to examine the PCM effect on heat and mechanical properties of cement mortar. Test results indicated that PCMs used in this study were effective to control hydration heat of cement mortar, and Barium-based PCM slightly reduce flow value. The compressive and flexural strength of cement mortar with PCM decreased with increasing the adding mount of PCM. The prediction model for compressive strength of cement mortar with different addition levels of PCMs are suggested in this study.

• Journal of Korean Society of Rural Planning
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• v.11 no.3 s.28
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• pp.53-57
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• 2005

Up to recently building are constructed focusing on the convenience of residential condition. However, environmental-friendly materials is required for construction as people are spending more time inside buildings and causes of many problems like sick-building syndrome are known due to the noxious gases and polluted air originated from construction materials. Although loess(hwangtoh) is an environmental-friendly material, it has limitations in compressive strength far a construction material. The purpose of this study is to suggest the optimal ratio of loess(hwangtoh) mortar by tests of compressive strength comparing with standard strength of floor finishing mortar and evaluate the usability of loess(hwangtoh) mortar for floor finishing material through an impact test, a cracking test and a abrasion test. Based on the results of this study, 86% of loess(hwangtoh) and 14% of inorganic binder is suggested for the optimal mixture ratio of loess(hwangtoh) mortar. Moreover, the characteristics of loess(hwangtoh) is suitable for floor finishing material in impact, crack, abrasion.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.11a
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• pp.165-166
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• 2022

In this paper, the characteristics of slag cement mortar added with neutralized liquid red mud with nitric acid to reduce pH by neutralizing liquid red mud with nitric acid were reviewed to improve strength degradation of cement concrete added with liquid red mud. As a result, the compressive strength of cement mortar added with liquid red mud was higher than that of Plain on 1 and 3 days, and the strength of red mud neutralized with nitric acid was lower than that of cement mortar added with liquid red mud on 7 days, but the strength was recovered on 28th. It was found that the addition of red mud has the effect of improving the strength in the early age.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2004.05a
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• pp.15-20
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• 2004

To the development on reusing method of the heat-source waste at Daegu Bisan dyeing-complex, this study is aimed to application of it's crushing material (hereafter waste sand) as concrete fine aggregate. The results are as follows; 1. Flow and unit weight of mortar using waste sand as concrete fine aggregate are decreased. 2. At the results of compressive strength test and bending strength test, mortar using waste sand superior to plain mortar within 80％ substitute ratio of waste sand. Because increasing rate of compressive strength is similar through increasing age, waste sand performs as filler's function of no-effect with cement only. 3. At the results of concrete application test, unit weight of concrete using waste sand is similar to plain concrete and compressive strength of concrete is superior to plain likewise the results of mortar test

• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.99-102
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• 1999

In the study, the effect of the replacement content(20, 40, 60, 80%) and particle fineness and the chemical activator of the fly-ash on the flow and strength development of mortar was investigated. We found that the higher raito of the fly-ash replacement produced the lower the mortar strength and the higher fineness of the fly-ash yielded the higher strength. Also, we used Na2SO4 as activator of fly-ash to rise compressive strength mortar. The result as follows: the fly-ash mortar which stimulated by chemical activator, was higher strength development at early than the fly-ash mortar without chemical activator. But in the late age, the result indicated adversely.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.220-223
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• 2004

It is fact that the cement is the most important material to harden the mortar and concrete, and Potland cement is used widely. Also, the chemical and physical properties of cement are different according to the kinds of cement. This is an experimental study to compare and analyze the influence of cement strength on the compressive strength of mortar to improve the quality of mortar and concrete. According to test results, it was found that correlation between cement strength and mortar strength was very high in all mixture.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2020.11a
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• pp.94-95
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• 2020

Oyster shells are characterized by coarse and coarse grains, but similar in strength to sand, and egg shells are fine grains but weak in strength. In terms of supply and demand of raw materials, oyster shells can be supplied only in limited periods and regions in winter and south coast of the year, but egg shells have the advantage of being able to supply and supply nationwide 365 days. This study aims to study the change in strength characteristics by mixing oyster shell powder and egg shell powder with the same particle size and mixing up to 150%. The conclusions of the flexural and compressive strength tests of mortar mixed with oyster shell powder and egg shell powder are as follows. The 7-day flexural and compressive strength with ESP added and the 3-day flexural and compressive strength with OSP added were similar, which is thought to be because the strength of OSP is higher than that of ESP.

• Proceedings of the Korea Concrete Institute Conference
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• 1994.10a
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• pp.441-446
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• 1994

In this study proposed to rapid and simple test method for early decision of quality of concrete. As the this paper is experimental study for compressive strength of mortar using resistance method, the obtained results are summarized as follow ; $\circled1$ The resistance ratio was decreased as the incement of water-cement ratio $\circled2$ The compressive strength presented to the tendency of increment as resistance ratio is increaing

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.05a
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• pp.63-64
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• 2023

In order to reduce the high absorption ratio of spent coffee grounds, this study examined the compressive strength and absorption ratio of mortar replacing coated spent coffee grounds according to the type of water repellent. In order to examine this, as the water repellent used, a silane-based water repellent (fluorine-based water repellent) and an acrylic-based water repellent, which are film-type water repellents, and a silane/siloxane-based water repellent, which are penetration-type water repellents, were used. The spent coffee grounds were coated with each of three water repellents, and mortar was prepared by mixing cement and fine aggregate. As a result of the experiment, the compressive strength and absorption ratio of the mortar replaced with coated spent coffee grounds coated with the film-type water repellent were superior to the penetration-type water repellent. Therefore, in order to reduce the high absorption ratio of spent coffee grounds, a suitable water repellent is a film-type water repellent. Among them, it is judged that the acrylic type has excellent water repellency and is suitable.