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시멘트의 수화특성에 대한 유·무기 복합 나노실리카의 영향
강현주,송명신,박종헌,송수재,Kang, Hyun-Ju,Song, Myong-Shin,Park, Jong-Hun,Song, Su-Jae 한국세라믹학회 2011 한국세라믹학회지 Vol.48 No.6
In this study, as a material used to replace silica fumes for high strength concrete, nano-silica compound with organic functional group for dispersion and with inorganic silica group that can cause a pozzolan reaction is synthesized, These nano silica compound is divided into IC, which is nano size $SiO_2$ with irregularly combined hydroxyl group and carboxyl group, and RC, which is nano size $SiO_2$ with regularly combined hydroxyl group and carboxyl group. The effects of these nano silica compound on the hydration of cement are reviewed. As a result, all of synthesized nano-silica compounds have excellent dispersion on the cement flow, we think that dispersion property is the effect of air entraining by synthesized nano-silica compounds. The result of the microstructure observation showed that the particle size of the synthesized nano-silica is smaller than silica fume and spread evenly among the cement particles. In initial The phenomenon of strength decreasing occurred due to delayed hydration reaction by the synthesized nano-silica with carboxyl(-COOH) and hydroxyl(-OH) functional group.
고성능 감수제 종류에 따른 실리카흄이 혼입된 시멘트 수화 특성
강현주,송명신,박종헌,송수재,Kang, Hyun-Ju,Song, Myong-Shin,Park, Jong-Hun,Song, Su-Jae 한국세라믹학회 2011 한국세라믹학회지 Vol.48 No.6
In this study, the effect of superplasticizers on the dispersibility and hydration properties of cement with silica fume were investigated. Superplasticizers are used Naphthalene type, Ligno-sulfate type and polycarboxylate type. Compared with plastic viscosity of cement paste without superplasticizers(Plain), plastic viscosity of cement paste with superplasticizers are reduced and yield stress of cement pastes with each superplasticizer is increased rather than Plain. And then, plastic viscosity of cement paste with Naphthalene type superplasticizer was the least of all types. Compared with other two types, setting and hydration of cement paste with Polycarboxylate type(PC) superplasticizer is very fast. At compressive strength after 3-day, PC is higher than other two types, But, compressive strength of after 7-day and 28-day, PC is smaller than other two types.
이종호,홍기영,허갑범,이현철,임승길,이은직,김경래,송영득,정윤석,문수재,심문정,박유경,송현용 대한내분비학회 1993 Endocrinology and metabolism Vol.8 No.1
The most impotant parameter in predicting value of osteoporotic fracture is the level of BMD(bone mineral density). The formation of peak bone mass is important in the preventive aspect of osteoporotic fracture. Among the factors influencing the formation of peak bone mass, the hereditary influence is believed to be the most important. We studied the importance of hereditary influence in determing peak bone mass by comparing BMDs of mothers and their daughters in college, who are in the age of achieving peak bone mass. The BMDs of daughters were greater than those of mothers, and mean age of menarche in daughters was earlier than that of mothers. Inmothers, BMD of L2-L4 had significant positive correlatins with height, weight, and BMI, however femur neck had positive correlations with weight and BMI. In daughters, BMD of L2-L4 had significant correlatin with weight, total calorie intake and protein intake, but MBD of femur neck had correlation with weight, body fat and animal calcium intake. Daughters of osteopenic mothers might be advised to evaluate the bone mineral density at critical period for the formation of peak bone mass, to identify the risk factors and to encourage more calcium intake. In conclusion, the BMDs of daughters have strong positive correlation with those of mothers. Hereditary influence on peak bone mass can be strongly suggested, but common environmental factors cannot be excluded. (J Kor Endocrinol 8:66~71, 1993)