HIGH VOLUME FLY ASH CONCRETES WITH RICE HUSK ASH (R.H.A.) AS AN ADMIXTURE -STRENGTH

摘要

Investigations using high volumes of fly ash replacing cement in concrete have been carried all over the world to study its suitably for construction works. M.N. Haque et al concluded that high volume fly ash concretes up to 75% replacement of cement by fly as are suitable for base and sub base courses. Studies reported by Dr. Seshagiri Rao et al have indicated that incorporating Rice husk ash as an admixture in the strength and durability characteristics. Another set of studies reported by Dr. Seshagiri Rao et al on incorporating high volume of fly ash up to 100% as an additional materials has indicated improvement in strength up to 70% of fly ash by weight of cement as an additional material. In the present studies, investigations are carried out using high volumes of fly ash as high as 100% by the weight of cement as an additional material and 10% Rice husk ash as an admixture to study the strength characteristics of the concretes and the results have shown that the strengths have been improved with the addition of 10% rice husk ash as an admixture. However addition of high volumes of fly ash results in drop in workability, which is due to the increase in surface area, necessitating the usage of super plasticizers. The addition of rice husk ash as an admixture doesn't contribute much to the strength characteristics of high volume fly ash concrete. Further it is observed that it decrease the workability due to the cellular structure.