جستجوی مقالات مرتبط با کلیدواژه "melamine powder" در نشریات گروه "شیمی"

Coastal area construction provides the biggest challenges in the country's development. Mechanical strength and durability are the two main challenges in coastal areas when compared to conventional construction. The proposed study explores the effect of recycled melamine powder and  poly (vinyl-co-ethylene) copolymer on workability, setting time, aggregate-to-cement adhesion, and the effect of moisture and saline water on concrete mechanical properties. Portland cement was sieved and dried sand, and aggregate was mixed in the ratio of 1:2:4 (cement: sand: aggregate) by weight. The three constituents were manually mixed with 40-45 wt. % tap water, based on cement content, until a homogenous mixture was visibly observed. Cylindrical samples with continuous tampering to avoid voids were cast in standard molds of 4”x 8” (100 x 200 mm) dimensions. The molds were covered and left for 24 hours for setting. Unmolded concrete samples were cured for 7 and 28 days in tap water. The concrete samples were dried and stored for further testing. The same concrete samples were prepared with an additional 1 wt. % and 3 wt. %, based on the cement content, of melamine and poly(vinyl-co-ethylene) copolymer. The samples were subjected to water slump height, water permeability, compressive strength and flexural tests, and carbonation tests. The results showed a 10 % and 16 % decrease in slump height for 1 % and 3 % loadings, respectively for both polymers when compared to controlled samples. Reinforced concrete showed less water penetration for both polymers due to their hydrophobic nature. Higher compressive and flexural strengths and low carbonation depth were obtained for reinforced concrete irrespective of the polymers used in this research.