• Journal of The Korean Society of Agricultural Engineers
• /
• v.48 no.1
• /
• pp.51-60
• /
• 2006

This study was conducted to investigate experimentally the drying shrinkage and the strength properties of redispersible SBR and PAE powder-modified mortars. Polymer-cement ratio, content of shrinkage-reducing agent and antifoamer content were manipulated as the experimental variables. The peculiarity of this study is to obtain a high early-age strength by using the portland cement and alumina cement with the ratio of 8 : 2. Until 7 days of age, the drying shrinkage remarkably increased up to $1\~2\times10^{-4}$, while it tended to decrease as the ratio of polymer to cement ratio and the content of shrinkage-reducing agent increased. Polymer-cement ratio was effective in improving the flexural, tensile and adhesive strengths: As the ratio increased, the strengths correspondingly increased. The flexural strength was in the range of $7\~11$ MPa, the tensile strength was $3.5\~5$ MPa and the adhesive strength was $1.2\~3.9$ MPa. On the other hand, the compressive strength tended to decrease as the polymer-cement ratio increased, and it was in the range of $23\~39$ MPa. All strengths, flexural, tensile, adhesive and compressive strengths, decreased as the content of powder shrinkage-reducing agent increased. It turned out that the polymer-cement ratio influenced more on the behavior of drying shrinkage and the properties of strength than the powder shrinkage-reducing agent did.

• KIEAE Journal
• /
• v.10 no.5
• /
• pp.131-137
• /
• 2010

The building industry must aim at high-durability and sustainability. A holistic life cycle based approach is recommended to reduce the environmental load. In recent years, technical innovations in the construction industry have advanced to a great extent, and caused the active research and development of high-performance and multifunctional construction materials. Nowadays, various polymer powders have been commercialized to manufacture construction materials in the form of prepackaged-type products, which have rapidly been developed for lack of skilled workmen in construction sites. Recently, terpolymer powders of improved quality have been developed and commercialized as cement modifiers. And, hydrocalumite is a material that can adsorb the chloride ions (Cl-) causing the corrosion of reinforcing bars and liberate the nitrite ions (NO2-) inhibiting the corrosion in reinforced concrete, and can provide a self-corrosion inhibition function to the reinforced concrete. The purpose of this study is to ascertain the self-corrosion inhibition function of polymer-modified mortars using redispersible powders with hydrocalumite. Polymer-modified mortars using VA/E/MMA and VAE redispersible powders are prepared with various calumite contents and polymer-binder ratios, and tested for chloride ion penetration depth, corrosion inhibition. As a result, regardless of the polymer-binder ratio, the replacement of ordinary portland cement with hydrocalumite has a marked effect on the corrosion-inhibiting property of the polymer-modified mortars. Anti-corrosion effect of polymer-modified mortars using VA/E/MMA terpolymer powder with hydrocalumite is higher than that of VAE copolymer powder.