Properties of Light Weight Concrete Made With Expanded Perlite and Pumice

Abstract

In design of concrete structures, light weight concrete plays a prominent role in reducing the density and to increase the thermal insulation. These may relate of both structural integrity & serviceability. More environmental and economical benefits can be achieved if waste materials can be used to replace the fine light weight aggregate. The new sources of structural aggregate which is produced from environmental waste is natural aggregates, synthetic light weight aggregates. The use of structural grade light weight concrete reduces the self weight and helps to construct larger precast units. Typical lightweight concrete aggregates are expanded clay or shale, expanded perlite, natural porous materials like vermiculite or pumice. Lightweight concrete is made by replacing natural aggregates with lightweight coarse aggregates and fine aggregate. The structural density of normal concrete is 24 KN/m3, which is very high, but the density of lightweight concrete varies from 4KN/m3 to 22 KN/m3. The merits of such materials in LWC are that they are porous in nature. The reduction of material and developing pores are beneficial in reducing dead weight. It is of paramount importance that research on LWC be extended and intensified to incorporate other tests that normally are done on normal concrete. By doing so, the effectiveness of LWC can be compared to normal concrete. Present research have been carried out by replacing fine aggregates with expanded perlite and pumice aggregates to attain light weight concrete. In this experimental study, various substitutions such as 25%, 50%, 75% and 100% of expanded perlite (EP) and combination of pumice and expanded perlite (PP) with fine aggregates have been done. Properties of fresh concrete like density and workability for each mix entailing expanded perlite and pumice with expanded perlite are evaluated. Compressive, split tensile, flexural strength as well as density, water absorption and total voids volume were determined for 28 days old lightweight concrete samples. Durability properties such as sorptivity, rapid chloride permeability tests were performed .The test results showed an overall strength & weight reduction in various substitutions of fine aggregate with expanded perlite and pumice. Results show that PP mixes are more strong and durable than EP mixes which is due to more compactness of the mix. Microporosity of granules was observed and visual inspection of their microstructure was done by using scanning electron microscope (SEM).