1997 Volume 8 Issue 2 Pages 51-59
To obtain a super workable concrete which can be cast without vibration, both deformability and resistance to segregation must be taken into consideration. Some agents made from polysaccha-rides are reported to have resistible activities of material segregation, but there is no report on an application of polyamino acids as a resistible agent to segregation. Then, we applied to use a γ-polyglutamic acid (γ-PGA) for the agent. As the result, the super workable concrete containing the γ-PGA produced from Bacillus subtilis (natto) indicated a suitable resistance to segregation. To estimate the mechanism of the resistible activity, the plastic viscosity and the yield value of cement pastes were measured. The γ-PGA increased the yield value rather than the plastic viscosity. It was suggested that the γ-PGA contributed to making the interaction between cement particles without increasing the viscosity of water.
