High-performance Concrete Admixtures

The development tendence of concrete is high performance concrete (HPC) with high strength, high working performance and high durability. In order to meet needs of HPC, some HPC admixtures were synthesized to insure high reducing water ratio, high adaptability, high durability and well workability in concrete. The HPC admixtures not only can reduce the mixing water content in concrete and keep fresh concrete good workable during transport and construct procedure, but also ensure concrete harden concrete having well properties of strength, impermeability, frost-resistant, corrosion resistant.High water reducing agents in domestic market usually are naphthalin, tripolycyanamide, sulfamate and lipopectic serials. Serials of naphthalin and tripolycyanamide have low water reducing efficiency, bad flow degree under low water cement ratio and sharp loss of concrete slump. Those properties have disadvantage on concrete transport and construct procedure. Serials of sulfamate are excessively sensitive to water content. Because the low addition amounts of sulfamate have little effect on the water reducing efficiency and the high addition amounts may result segregation and bleeding in concrete, so the addition amounts of sulfamate are difficult to control in the practice. The traditional serials of lipopectic have not been widely used because its produced periodic time is very long, its deep color may effects the concrete color and it may cause sharp loss of concrete slump. The research in the paper is to modify the traditional serials of lipopectic and to synthesize new high water reducing agents.The serials of lipopectic water reducing agents were synthesized by condensation reaction between aldehyde and ketong, the α -H sulfomethylation reactions were introduced sulfonic group to control molecular weight and water solubility, and the condensation degree and sulfonation degree of were controlled by adjusting the proportion of aldehyde and ketong. Thus molecular structure with high water reducing effect, good maintained plastic property could be abtained.The results reveal that principal chain structures without big radicals are prepared by changing traditional preparation method of lipopectic water reducing agents, the reaction time can...