Durability Studies on Modified Concrete Using LECA and Sintered Fly-ash Aggregate and Blended Cement With Pozzolanic and Nano Materials

Abstract

In the contemporary LPG (Liberalisation Privatisation & Globalisation) trend application of light weight concrete is souring up day by day. The lightweight concrete has many advantages compared to conventional concrete like providing thermal acoustic insulation, and producing of light weight structures with the less number of structural components and steel reinforcement. This gradually minimise the construction cost. In addition to the sound mechanical strength properties, longstanding durability properties also regulate the efficiency and effectiveness of the concrete. Durability of lightweight aggregate concrete is its resistance against the atmospheric and human induced gases, various chemicals and fluctuations in temperature etc. which reacts vigorously or moderately with the various binder elements of the concrete causing degradation. In general Concrete structures will get expose to various environments under certain circumstances such as proximity to industries which releases chemicals and emits various gases; acid rains, hot springs etc., and the course of interaction may vary from few seconds to many years. While coming to resistance to various environments, the durability of lightweight concrete is mostly influenced by materials that are under acid, chloride and sulphate environment.

In this study, an attempt is made to study the impact and effect on the specimens of modified concrete which are demoulded after 24 hours of casting and placed in the 5% of acidic solutions such as i) Hydrochloric Acid (HCl), ii)  ulfuric Acid (H2SO4) to study acid attack and 5% of alkaline solutions such as i)Sodium Sulphate (Na2SO4), ii) Sodium Chloride (NaCl) solution to study sulphate and chloride attack after 28 days and 90 days of curing and the results are compared with those cured in plain water. Modified concrete is obtained by 100% replacement of naturally available coarse aggregate with light weight aggregates like Sintered fly-ash aggregates and LECA (Light Expandable Clay Aggregates) in equal proportions along with 3 no’s of pozzolanic materials i.e., silica fume, fly ash and slag in equal proportions which collectively replaces 11% of cement in addition to the varying percentages i.e., 0%, 0.5%, 1.0%, 1.5% of Nano materials(TiO2 & SiO2) on 11% weight of cement in equal proportions. Various tests have been carried out on the above samples like density variation, cube compressive strength, split tensile strength, and Sorptivity. Results indicate that the concretes containing pozzolans have better performance in comparison to the concretes which are produced without pozzolans and also the resistance of concrete increased with addition up to 1% of TiO2 & SiO2 in equal proportions and decreased beyond that.