Biography: Dr. Kung-Chung Hsu received Ph.D in Department of Chemical Engineering at The Penn State University, in 1985. He worked as a senior scientist in the R & D Department of China Steel Corp. in 1985-1990. He was an Associated Professor in 1990-1996, and has been a professor in the Department of Chemistry of National Taiwan Normal University, Taipei, Taiwan, since 1996. Dr. Hsu has research interests in (1) preparation and application of dispersing agents in ceramic materials, (2) preparation and development of superplasticizer and self-curing agents in concrete, and (3) preparation and application of nano powder and graphene/polymer composites. So far he has published more than 50 peer-reviewed papers and obtained over 20 patents.

Topic: Pozzolanic Material/Hydrogel Composites: Synthesis and Applications in Concrete

Abstract: Superabsorbent polymers (SAP) or hydrogels can absorb water up to thousands of times its dry weight. Their high absorption property enables SAPs to be used as a concrete internal curing agent which can effectively delay the decrease in internal humidity, mitigate the drying shrinkage and autogenous shrinkage of concrete. Currently, crosslinked polyacrylic acid (PAA) and acrylic acid-co-acrylamide (P(AA/Am) are mainly used as an internal curing agent. Several papers indicated that incorporation of these hydrogels caused a reduction of compressive strength of the resulting cementitious materials.
To resolve the problem mentioned above, several pozzolanic material-containing P(AA/Am) hydrogel composites (P(AA/Am)/Po) were prepared. The pozzolanic materials such as fly ash and silica fume were used. The water absorption behavior of P(AA/Am)/Po in the pore solutions was studied. The prepared polymer composites were added in mortars and the effects of Po content on the properties of cementitious materials were investigated. The results indicated that the water absorbency of hydrogel composites in the pore solution was higher than the pure hydrogel without Po present. Mortars with P(AA/Am)/Po composite showed higher compressive strength and lower drying shrinkage than those with P(AA/Am). The reasons are that the Po-containing composite has higher compressive strength than the pure hydrogel. Furthermore, the pozzolanic material inside the composite could proceed the pozzolanic reaction with the pore solution and formed C-S-H gels.