• Magazine of the Korea Concrete Institute
• /
• v.8 no.5
• /
• pp.135-143
• /
• 1996

Diffusion of water in hardened cement concrete and mortar influences on the dry shrinkage. creep. modulus of' elasticity, etc. In general, water loss through drying process in polymer-modified concrete and mortar is small compared with that of unmodified concrete and mortar due to the films formed by polymer as cement modifieder. The purpose of this study is to investigate the diffusion process of water in the polymer-modified mortars. The polymer-modified mortars using three polymer dispersions and epoxy resin are prepared with various polymer-cement ratios, and water diffusion coefficient of polymer-modified mortars according to inside water content is calculated. From the test results, the water diffusion coefficient of polymer modified mortars i s smaller than that of unmodified mortars and decreases with increasing polymer cement ratio.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.4 no.2
• /
• pp.165-171
• /
• 2016

The objective of this study is to evaluate the compressive strength development and ecological characteristics of mortars using expanded vermiculite absorbing bacteria as a fundamental investigation to develop precast eco-concrete products. For bacterial growth under the high-alkalinity and high-dried environments within hardened mortars and for creating plant growth function to mortars, Bacillus alcalophilus and Rhodoblastus acidophilus were separated and cultured. The cultured bacteria were absorbed into expanded vermiculite selected for bacteria shelter. The expanded vermiculite absorbing bacteria was then added into mortar mixture as a volumetric replacement of fine aggregate. Test results showed that the developed technology is very effective in enhancing the plant growth onto the hardened mortars and reducing the COD and T-N concentration in raw water. The optimum replacement level of expanded vermiculite absorbing bacteria can be recommended to be less than 10% considering the compressive strength development and cost of mortars along with the ecological effectiveness.

• Journal of the Korea Institute of Building Construction
• /
• v.13 no.3
• /
• pp.235-241
• /
• 2013

In this study, a mortar was produced using re-dispersible polymer powders that addresses the defects of aqueous polymer and improves the durability of cement mortar. Also, an attempt was made to examine the properties of polymer modified mortars using re-dispersible polymer powders by strength and durability tests between ordinary Portland cement mortars and polymer modified mortars mixed with aqueous dispersion. The test showed that strength and durability are improved considerably compared with ordinary Portland cement mortar, and the performance of aqueous polymer cement mortar was considerably improved. Accordingly, it is expected that high-quality prepackaged polymer modified mortars can be produced using re-dispersible polymer powders.

• International Journal of Concrete Structures and Materials
• /
• v.4 no.2
• /
• pp.109-112
• /
• 2010

Part I of this study was devoted to the electrical accelerated chloride diffusion in mortars. In this second part, natural chloride diffusion has been investigated for four types of mortars under exposure to a 0.5 mol/L NaCl solution for a period of up to 35 days. Two different types of sand were used for the production of test samples: siliceous sand (used as a reference) and limestone sand (used in this study). The effect of water to cement ratio and exposure time on the diffusion coefficients of mortars was also investigated. In this study, the total and free chloride content and penetration depth of mortar were measured after immersion, and Fick's second law of diffusion was fitted to the experimental data to determine the diffusion coefficient. Their results show that the use of crushed limestone sand in mortar had a positive effect on the chloride resistance. The apparent diffusion coefficient in all specimens was smaller than that in siliceous sand mortar. However, the chloride penetration of these mortars was increased as exposure time progressed.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.25 no.1
• /
• pp.39-43
• /
• 2015

The cement mixtures such as flyash, iron-slag and silica fume have been actively studied in order to increase the quality of concrete. In this study, the grinded copper-slag with different proportion was added to portland cement. The physical properties of the cement mortars, (i.e.) flowability, absorption, compressive strength and flexural strength, were investigated for the potential application to the cement. Also, the influence of the acid on the chemical resistance of the cement mortars with copper-slag was evaluated by monitoring the weight variation of the cement mortars under 5 % sulfuric acid for 28 days.

• Journal of the Korean Ceramic Society
• /
• v.24 no.3
• /
• pp.289-295
• /
• 1987

The changes of physical properties of portland cement pastes and mortars were investigated by addition of sodium gluconate. Flow table experiment and viscosity measurement were took in order to find dispersing effect, and time-dependent changesof viscosity and rates of hydration heat evolution were carried out for the sake of finding retardation effect of hydration. And changes of physical properties of cement pastes and mortars were discussed by setting time, compressive strength and porosity.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2006.05b
• /
• pp.301-304
• /
• 2006

The purpose of this study is to evaluate bonding properties of PMMA mortars using EPS with silane coupling agent. PMMA mortars are prepared with various silane coupling agent, and tested for flexural strength test, adhesion test in flexure and tensile strength in underwater and air. It is estimated that the application of silane coupling agent to PMMA mortar is more effective in underwater than air.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1997.10a
• /
• pp.641-646
• /
• 1997

Polymer cement mortar which is used as material for aging concrete structures is generally mixed manually and applied on the job site. but, to secure the required quality of the mortar, pre-mixed polymer cement mortar is favored. This study was initiated to four different pre-mixed polymer cement mortars which are produced in Korea. The for pre-mixed mortars were selected and tested with respect to physical and mechanical properties an proved that their qualities were better than those of common cement concrete mortars.

• Advances in concrete construction
• /
• v.9 no.3
• /
• pp.227-234
• /
• 2020

Raw perlite is a volcanic alumino-silicate and is used as aggregate in the construction industry. The high silica and alumina contained in the raw perlite allows the production of geopolymer mortar with the help of alkaline solutions. In this study, different geopolymer mortars are obtained by mixing ground perlite (GP), sodium hydroxide (NaOH), water and CEN standard sand and the strength and microstructure of these mortars are investigated. Mortar specimens are placed in the oven 24 hours after casting and kept at different temperatures and times, then the specimens are cured under laboratory conditions until the day of strength tests. After curing, unit weight, ultrasound pulse velocity, flexural and compressive strengths are determined. Experimental results indicate that the mechanical properties of the mortars enhance with increasing oven-curing period and temperatures as well as increasing NaOH molarity. In addition, SEM/EDS and XRD analyses are performed on the mortar specimens and the results are interpreted.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2001.05a
• /
• pp.475-480
• /
• 2001

Mechanical properties of mortars and concretes blended with GCC(Ground Calcium Carbonate slurry) and silica fume were investigated. Results from this study showed that air contents of mortars were constant regardless of replacement of GCC and flow values of mortars were decreased with replacement of it. Especially, mortars and concretes replaced with 10% of GCC had a good trend with respect to compressive strength. In case of simultaneous use of GCC and silica fume, the workability and compressive strength of the concretes seem not to be any problems in mechanical properties. This study indicated that the most reasonable replacement of GCC was 10% and the addition as fine aggregate was more effective than that as binder.