Synthesis And Properties Of, New Air Entraining Agent Poa-10

The development of air-entraining agent(AEA)is one of the most important advances in concrete technology last century.It is well-known that AEA can improve the workability of the fresh concrete and improve the frost resistance and permeability of the hardened concrete.However, there are few kinds of air-entraining agent now,which are not now in common use all over China.The composition and the preparing process of a new air-entraining agent for concrete were discussed is this paper.It was composed of the surface-active agent A and the low molecular weight polymer B.First,the surface tension of the solution,the capacity forming air bubbles,the stability of air bubbles and strength of air bubbles film were measured; Then,the component and synthetize method of the new AEA were determined.By testing the effect of the new AEA on the performance of the mortar and concrete,the differene between the new AEA and the one used widely whose main chemical component is triterpenoid saponin were discussed.The test results show that the component and synthetize method of the agent can be optimized by testing surface tension,capacity and stability of air bubbles and strength of air bubbles film.And the best component of the AEA named POA-10 was obtaind.The mol ratio of active functional group of the material A and B is 6:1.Adding POA-10 can reduce the bleeding of the fresh concrete and the self-shrinkage of the mortar.And the resistance to chloride ion penetration and frost are improved obviously.When the air content of the concrete is 5%,the chloride diffusion coefficient is 2.07×10¹²m²/s less than the standard concrete,and the relative dynamic elastic modulus is 70.01%after 300 freeze-thaw circles whereas the standard concrete is destroyed after 200 freeze-thaw circles.When the air content of the air-entrained concrete is 5.1%,the strength loss is 11%.The best mixing amount range of POA- 10 is 0.02%to 0.05%.However,the air content was influenced by many factors,such as the kinds of cement,water to cement ratio,sand ratio,fly ash,water-reducing agent and mixing time and so on.The best mixing amount of AEA should be determined by test on site.By comparing the POA-10 and the AEA whose main chemical component is triterpenoid saponin,the former have better performance improvement and economic demand,the latter have similar performance of strength and anti-frost.The studies show that POA-10 is a new air-entraining agent with high quality,and can be used widely in the civil construction.The economy benefits will be got by using the POA-10.