Corrosion of Reinforcement in HVFA Concrete

Abstract

bstract: Concrete is a composite material composed of fine aggregate and coarse aggregate bonded together with cement that hardens over time. Concrete is one of the most frequently used building materials. Water cement ratio plays an important role which influences various properties such as workability, strength and durability. In concrete cement is main concrete material.The use of fly ash as an addictive material, as replacement of cement. The most important benefit is reduced permeability to water and chemicals. Properly cured concrete made with fly ash creates a denser product because the size of pores is reduced. This increases strength and reduces permeability and corrosion. For concrete mixes 43 grade of ordinary Portland cement and class F type Fly ash is concrete cubes are casted with varying percentage of fly ash and ultrafine fly ash. Three types of percentage is used as replacement of cement with fly ash. For replacement 40% ,50% and 60% fly ash is used. The size of cubes is 150mm x 150mm x150mm.Water/cement ratio 0.36 and Four types of percentage of Ultra fine fly ash is added such as 6%,8%,10% and 12%. Test is carried out after 7 days and 28 days of curing period. The tests conducted on concrete specimens are compressive strength. Results show that the addition of 6 wt.% UFFA significantly improved the early age and later age compressive strengths of HVFA concretes. The HVFA concrete containing 50% fly ash and 6% UFFA exhibited higher corrosion resistance properties. The results also indicate the effectiveness of UFFA in producing high packing density and in accelerating the pozzolanic activity to produce more C–S–H gel by consuming calcium hydroxide (CH) in HVFA concretes.