Effect of Size and Dosage of Microsilica on Compressive Strength Along With Microstructural Analysis of Concrete

V. Nagendra
2018 International Journal for Research in Applied Science and Engineering Technology  
The present study investigates the effect of microsilica as partial replacement for cement in concrete with different range of particles at different dosages. The grade of concrete used in the study is M20.The compressive strength is obtained for the particles ranging from 0-20 µm, 20-45µm, 45-90 µm, 90-125 µm and 125-250 µm, and the replacement is from 10% to 40% at an increment of 10%. The microstructural study is carried out using scanning electron microscopy (SEM) and energy dispersive
more » ... rgy dispersive spectrometer (EDS).The two main compounds observed in the study are Silica and Calcium, their consumptions before and after the pozzolonic reactions are studied. The optimum compressive strength is observed for 0-20 µm size particles at 20% replacement level and it is also observed that the consumption of calcium is more for the above said replacement. Key words: Microsilica, scanning electron microscopy (SEM), energy dispersive spectrometer (EDS). I. INTRODUCTION Microsilica is a by-product obtained by the smelting process in the silicon and ferrosilicon industry. The reduction of high purity of quartz material to silica at temperatures reaching 2000 0 C generates silica vapours which oxidizes and condense in the low temperature zone to low particles containing non-crystalline silica. .Microsilica is also identified as silica fume, condensed silica fume, volatilized silica or silica dust. Microsilica has been recognized as a pozzolanic admixture that is effective in improving the mechanical properties to a great extent. By using microsilica along with super-plasticizers, it is comparatively easier to obtain higher compressive strength. Concrete has a highly heterogeneous and complex microstructure, it is difficult to predict actual models of its microstructure from which the action of the contents can be properly predicted. The acquaintance of the microstructure, the properties and influences of the individual components of concrete and their inter-relationship are useful for working out control on the properties of concrete. The term microstructure indicates the structure which develops in concrete at a micro level, when water is added to cement and aggregates. To understand the cause, extent and mechanism of deterioration, or how to improve some of the properties of concrete, a thorough awareness of the basic microstructure of hardened concrete is required .Mechanical properties of concrete more often depend on its intrinsic microstructure. The high resolution capability of SEM coupled with EDS/EDXA has opened a world of opportunities in the field of concrete technology. The microstructure of concrete is described as an integrated system consisting of (i) hydrated cement paste (ii) coarse and fine aggregates and (iii) the interface between aggregate and hydrated cement paste, also known as interfacial transition zone (ITZ). Reference as in [1] investigated the strength of silica fume concrete at a constant water binder ratio (w/b) of 0.34 and replacement percentages varies from 0 to 25. The maximum 28 day compressive strength was obtained at 15% replacement level. They also studied the silica fume effect with different water binder ratios. In their study it is observed that the maximum strength was obtained at 25% replacement of cement by silica fume. [2] studied the workability and the compressive strength of silica fume concretes for low water-cementations materials ratios with super plasticizer. They observed optimum compressive strength at 20% replacements and the strength gain is less than 15%. [3] have investigated, effect on strength and chemical resistance of concrete for M25 grade by using microsilica 920-D. The percentage of microsilica used in the investigation is ranging from 0% to 40%. The optimum strength is obtained at 10% replacement. [4] reported that the strength of silica fume concrete is greater than that of silica fume paste which they attributed to the change in the role of the aggregate in concrete.[5] investigated the influence of silica fume on the compressive strength of high performance concrete.[6] stated the difference in strength development in OPC concrete and silica fume concrete. [7] studied the compressive strength of high performance concrete. [8] studied the compressive strength of concrete containing silica fume and w/c ratio kept as variable factor. [9] designed the concrete mixtures to evaluate the effect of silica fume on the compressive strength. [10] investigated the
doi:10.22214/ijraset.2018.3010 fatcat:r77iq3jwczczpiba5skdqm6tiq