The influence of processed fly ash on the properties of Self compacting concrete in fresh and hardened state

Abstract

During the last two decades new cementitious materials are available in the construction industries. These represent a sort of technical revolution with respect to traditional concretes. The most important innovative high technology material is Self Compacting Concrete (SCC). This paper presents the results of an investigation to evaluate the suitability of different percentages of processed fly ash as cement replacement material in SCC. An experimental study has been performed with different SCC mixtures containing total binder content of 450, 500 and 550 kg/m³ in which 30%, 40% and 50% of the contents have been replaced by processed fly ash with fineness residue retention on 325 mesh sieve less than 12%. The water content for all the mixtures was kept constant as 195 lit/m³ and self compacting ability was arrived by using superplasticizer. The different mixtures were investigated on fresh concrete with respect to selfcompactability (slump flow, L- box, V- funnel and U – funnel flow) and mechanical properties, viz., compressive strength, split tensile strength, modulus of rupture and durability properties of rapid chloride permeability test (RCPT). The slump flow, L – box ratio and U – box ratio values satisfied the stipulation laid down in European Federation dedicated to specialist construction chemicals and concrete systems EFNARC 2005 by all the mixtures except the V- funnel flow test. The mechanical properties of all the mixtures showed increase in strength with increase in curing ages and marginal reduction in strength by increasing the processed fly ash levels. The charges passed in RCPT test showed marginal reduction by increasing the cement replacement levels by processed fly ash and enormous reduction in values with increase in curing age. This paper briefly discussed about the preparation of mixtures and test methods, test results and discussions and the conclusions arrived based on the test results.