• Journal of the Korean Recycled Construction Resources Institute
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• v.4 no.2
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• pp.101-111
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• 2016

It is possible that aggregates add on to geopolymer based fly ash to mix mortar and concrete like cement. This is necessary to evaluate mineral composition, particle shape, surface, size distribution, density and absorption ratio for fine aggregates due to few detailed research to examine influence of fine aggregates properties on unhardened geopolymer concrete. In this research, used two different fine aggregates, Jumunjin sand(having quartz, mica, feldspar, pyroxene in mineral composition, more than 96% of total size between -0.60 and +0.30mm, angular shape and rough surface) and ISO sand(having almost all quartz in mineral composition, more than 51% size between -1.40 and +0.60mm, simultaneously varied size distribution, spherical shape and smooth surface). After an experimental result of the varied ratio of Si/Al=1.0-4.1 geopolymer paste, mix proportion respectively applied Si/Al=1.5 having the highest compressive strength to mortar and Si/Al=3.5 having the highest consistency to concrete. Geopolymer mortar by mixing with Jumunjin and ISO sand in varied range of 20-50wt.% showed flow size increase between 69.5 and 112.0mm, between 70.5 and 126.0mm respectively. Geopolymer concrete at an addition of 77wt.% of total aggregates ratio showed that average compressive strength was 32MPa and the consistency was favorable to molding. Since ISO sand observing varied size distribution, spherical shape, smooth surface, low absorption ratio resulted in advantageous properties on consistency of geopolymer, geopolymer concrete can be suitable for using the fine aggregates similar to ISO sand.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.2
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• pp.124-134
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• 2013

This study investigated the effect of surface water on concrete substrate on adhesive strength in tension of very high flowable SBR-modified cement mortar. The specimens were prepared with proportionally mixing SBR latex, ordinary portland cement, silica sand, superplasticizer and viscosity enhancing agent. Polymer cement ratio (P/C) were 10, 20, 30, 50 and 75% and the weight ratio of fine aggregate to cement were 1:1 and 1:3. The specimens obtained with different P/C and C:F were characterized by unit weight, flow test, crack resistance and adhesion test. After basic tests, two mixtures of P/C=20% and 30% in case of C:F=1:1, and one mixture of P/C=50% in case of C:F=1:3 were selected, respectively. These three selected specimens were studied about the effect of surface water evenly sprayed on concrete substrate by a amount of 0, 0.006, 0.012, 0.017, 0.024g per unit area ($cm^2$) of concrete substrate surface The results show that surface water on concrete substrate increases the adhesive strength in tension of high flowable SBR-modified cement mortar and improve the flowability compared to the non-sprayed case.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2011.11a
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• pp.107-108
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• 2011

The purpose of present study is to examine the application of effective curing to hardener-free epoxy-modified mortars. The epoxy-modified mortars are prepared with polymer-cement ratios, subjected to two types of curing conditions, and tested for compressive, flexural and tensile strengths. As a result, hardener-free epoxy-modified mortars with steam curing is markedly improved with increasing air-dry curing period. High strength development of the epoxy-modified mortars may be achieved by the dense microstructure by cement and the hardener of the epoxy resin in the mortars.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2013.11a
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• pp.175-176
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• 2013

Nowadays, energy-saving has become important in the construction industry. Above all things, outside insulation on buildings is important in measure of energy-saving. However, its insulation performance is degraded by the problem of that Cement-polymer modified waterproof coatings are used mostly for covering plaster mortar. In this study, we examine the optimum size of the silica and how does silica's size effect on physical properties of outside insulation covering plaster mortar.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.05a
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• pp.1011-1016
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• 2001

The purpose of this study is to find out the effect of polymer glass transition temperature on mechanical properties of polymer latex-modified mortars in comparison with ordinary cement mortar. The Polymer latex-modified mortars are prepared with 5, 10, 15 and 20% of polymer cement ratio respectively, and properties of modified mortars such as air content, compressive, flexural and tensile strengths are tested. The test results indicate that the types of polymer dispersion and the polymer-cement ratio are very important factors to characterize the properties of polymer-modified mortars, and also the glass transition temperature of polymer dispersions has an important effect on the performance of polymer-modified mortars. The modifying effects of two kinds of polymer dispersion, St/BA-1 and SBR, are evaluated.

• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.499-500
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• 2009

This study was performed to evaluate bonding strength of the composites section made of existing concrete and repair mortar in domestic. The pull-out tester was used to test bonding strength for the composites section made of each materials. The results of the test was used to evaluate the korean industrial standard of polymer modified cement mortars for maintenance in concrete structures.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.533-536
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• 2005

Drying shrinkage and strength of the redispersible SBR and PAE powder-modified mortars were experimentally investigated. Results of the study that the drying shrinkage rapidly increased until 7 days of age and it was then saturated to the value of about $1\~2\times10^{4}$ after 14 days. It turned out that the polymer-cement ratio exerted more influence on the drying shrinkage than the content of powder shrinkage-reducing agent did. Flexural (compressive) strength of the mortar increased (decreased) as the polymer-cement ratio increased and it was 7$\~$11 (23$\~$39) MPa at 7 days of age. The average (maximum) increasing (decreasing) rate turned out to be about 10 (30) $\%$. As in the drying shrinkage case, the polymer-cement ratio exerted more influence on both flexural and compressive strengths than the content of powder shrinkage agent did.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.537-540
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• 2005

Durability of the polymer-modified mortars using the redispersible SBR and PAE powder-modified mortars were experimentally investigated. Results of a previous study were used to determine the mix proportion that optimized the strength, and the freezing-thawing resistence, the carbonation depth and the chloride intrusion depth of the mortar for various polymer-cement ratios were studied. After 300 freezing-thawing cycles, the rate of weight reduction decreased from 7 to below 2 $\%$ as the polymer-cement ratios increased from 0 to 15 $\%$, and, on the 150 cycle basis, durability index increased from 60 to 98. Carbonation depth decreased from initial value of 5.5 to about 2.5 mm and chloride intrusion depth did from 3.5 to 1.5 mm

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.3
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• pp.102-109
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• 2011

In this study, in order to develop ultra rapid hardening mortar(URHM) for tunnel repairs using bottom ash of low recycle ratio and Admixture as Eco concept, watertightness and durability properties of URHM on temperature condition of construction field were performed. Test result, seepage quantity and water absorption coefficient regarding watertightness of URHM were as in the following : series II > series I. Seepage quantity for the standard condition were smaller than low temperatures. all specimens were satisfied below 20g as standards of seepage quantity on KS F 4042. Because of the decrease of unit cement content by to replacement of blast furnace slag, the neutrlization resistance for durability properties was reduced. The result of alkali resistance and acide resistance, compressive strengths for specimens soaked in calcium hydroxide solution of seriesI were lower than compressive strengths for specimens not soaked. On the other hand, the case of series II show that the deterioration of compressive strengths for specimens was not almost showed. Compressive strengths of specimens soaked were similar with specimens not soaked except series II-C in $5^{\circ}C$. Therefore, specimens using both blast furnace slag and bottom ash were good in alkali resistance and acide resistance.

• Journal of the Korea Institute of Building Construction
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• v.15 no.5
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• pp.483-489
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• 2015

The Purpose of this study was to establish the basic data on the mechanical properties of PCM in the high temperature range. To this end, an experiment was conducted on the characteristics of the residual compressive strength by temperature (100, 200, 400 and $600^{\circ}C$) with a fixed temperature heating. An after heating test was performed to investigate the properties after fire damage. The result showed that the residual compressive strength of PCM had a tendency to decrease, regardless of the type of polymer. It was also found that when the contents were low, the residual compressive strength started to greatly decrease from the high temperature range of $400^{\circ}C$, and that the specimen containing PAE showed a steeper slope than the specimen containing EVA. However, since little studies have been conducted on the mechanical properties of PCM with the high temperature, it is considered that, in addition to this study, basic studies must be preceded, including studies on the repairing methods.