A Study on the Effect of Size of Aggregate on the Strength and Sorptivity Characteristics of Cinder Based Light Weight Concrete

Abstract

It is known that the largest maximum size of aggregate possible to handle could be used in concrete under a given set of conditions. There are benefits of choosing a correct maximum size of aggregate (MSA), viz. reduction in the cement content and drying shrinkage. Variation in the size of aggregate alters the micro cracking of concrete which there by modifies the strength and durability as well. Also, the strength and durability of concrete is dependent on sorptivity, an index of concrete permeability. The pore structure in LWA, which is otherwise porous in nature, can be modified with fly ash inclusion, which not only modifies the density but also enhances the durability of concrete. In the present study, the strength and sorptivity characteristics of concrete made with cinder-based lightweight aggregates are investigated. Prior to this the size of cinder based light weight aggregate was optimized. The present investigation aims at developing two grades, 20Mpa and 30Mpa, of light weight concrete using cinder based aggregate of different sizes. The results indicated that Light Weight Concrete can be developed with all sizes of graded aggregate satisfying the fresh and hardened state characteristics. The mechanical properties viz., compressive strength and split tensile strengths were studied at the end of 3, 7 and 28 days for medium grade concretes with different sizes of aggregate. It was noted that with 12.5mm size aggregate and 30% flyash replacement, the mechanical properties were superior in 20Mpa Light weight Concrete, while 10 mm size aggregate with a 30% fly ash replacement improved the properties of 30Mpa concrete. There was also an improved performance in terms of sorptivity of fly ash based Light weight Aggregate Concrete.