Title : A REVIEW ON EFFECTS OF NANOSILICA AND MICROSILICA ON MICROSTRUCTURAL AND MECHANICAL PROPERTIES OF CONCRETE
Authors : Lincy Varghese, VVL.Kanta Rao, Lakshmy Parameswaran
Publication : 8 - 10, October 2015
Volume : 2
Pages :
Price : 250
Abstract : Concrete has come off age from a simple mix of four major ingredients namely; cement, coarse aggregate, fine aggregate and water, to a complex mix of several chemical and mineral admixtures. Addition of pozzolans has significantly altered the properties of concrete paving way for high/ultra high ‘performance’ concrete which gave equal importance to strength, durability as well as sustainability. Flyash, silica fume (microsilica), slag, metakaolin, rice husk ash etc., are the commonly used pozzolans. Concrete is made by using materials ranging in size from millimeters (aggregates) to micrometers (pozzolans) which results in creation of pores of size from several microns to nanometers. Presently used materials are not completely efficient to modify the concrete pores at nano level to make it impermeable to the external deleterious agents. Nanosilica is emerging as an innovative ingredient for making of concrete. It acts as an active pozzolan in concrete overcoming some of the drawbacks such as delayed setting, slow strength gain etc., associated with the conventional mineral admixtures even at very small dosage (3 to 5%). Considering the high demand for concrete as a construction material, the availability of conventional pozzolans is becoming limited. Hence an interest is growing on use of synthetic pozzolans like nanosilica in concrete. Nanosilica is an amorphous silica material of high purity (~ 99% SiO2), and is 1000 times finer than microsilica. . Therefore, nanosilica can significantly refine the microstructure of concrete which in turn enhances its strength and durability. This paper presents a review of the effects of nanosilica and microsilica addition on the microstructural densification and mechanical properties of concrete.