MIX PROPORTIONING OF HIGH PERFORMANCE CONCRETE USING FLY ASH AND SILICA FUME

Abstract

Mix proportioning is the process which involves the determination of correct combination of its ingredients such that the resulting mix yields desired characteristics at its lowest possible cost. The proportioning of HPC requires a special method of mix design as compared to NSC because of its lower water-binder ratio and use of different chemical admixtures and supplementary cementitious materials that would change the properties of concrete in both fresh and hardened state. Chemical admixture is a must for the production of HPC to achieve the desired strength. The effect of admixture on the type of cement should be verified using trail mixes, as HPC uses both chemical and mineral admixtures (SCM). For the strength greater than 70 MPa, silica fume is a must for the production of HPC. BIS method of mix design is applicable for a maximum compressive strength of 40Mpa hence it cannot be applied directly for HPC. The mix proportions for the present study is carried out by the popular method proposed by Aitcin [Mehta P.K. and Aitcin P.C, 1990; Aitcin P.C, 1998]. Concrete of strengths 60, 80 and 100 MPa were developed by using locally available FA and CA with OPC 53 grade cement, SCM and superplasticizer.