Development of Mix Design of Light Weight Concrete

Abstract

Several attempts have been made in the past to minimize the inherent weight of concrete, which typically possesses a density of 2200 kg/m3 to 2600 kg/m3 when utilizing ordinary aggregates. Hence, it is imperative to reduce the overall dead load of the structure, a goal that can be accomplished by incorporating lightweight aggregates. Moreover, in addition to its reduced density, lightweight concrete also offers enhanced thermal insulation properties in comparison to traditional concrete. This study aims to produce structural lightweight concrete having a density of around 1800 to 2000kg/m3. For this purpose, two types of lightweight aggregates namely, LECA and Sintered Fly Ash aggregates have been used. The specific gravity of LECA is 0.6, whereas Sintered fly ash has a specific gravity of 1.72. The physical and durability properties such as water absorption, crushing value, impact value of specimens were examined. The Mechanical and Durability properties such as Compressive strength test, Flexural Strength Test, Split Tensile Test, were conducted.The main intention of carrying out this project is to compare the weight of concrete and the strength properties such as Compressive Strength, tensile strength,and Flexural strength of lightweight Concrete against conventional concrete by partially replacing natural aggregates with LECA and Sintered fly ash with 20%, 30%, 40% and 50%. The performance of lightweight concrete is influenced by the type and percentage of replacement material. From observation it is noted that by replacing LECA 20%, 30% and 40% it gives less compressive strength then by replacing it with 20%, 30% and 40% Sintered Fly ash. It is noted that by replacing with LECA and Sintered Fly ash there is no reduction on density. By replacement of 100% LECA it is noted that compressive strength is reduced and density remains same as conventional concrete. By replacement of 100% SFA-1 it is noted that compressive strength increases but density is not achieved. Thus, by adding cementitious material such as silica fume, pulverised fly ash, glass fiber and Sintered fly ash having specific gravity of 1.06 mix design is prepared. And it is noted that by replacement of 100% SFA-2 it is noted that compressive strength increases and density reduces so by adding cementitious materials such silica fume, fly ash and glass fiber density is decrease. To calculate overall dead load of the building a 2x2m slab for Normal M30 grade and Lightweight concrete were considered. Grade of concrete was considered as M30 and Fe415 grade of steel is assumed. Thickness of slab is considered as 120mm. Live load is assumed to be 1.5 KN/m3 and floor finish of 3 KN/m3.Reduction in steel in X-direction was 8% and in Y-direction about 7% reduction in steel was observed.Thus it is observed that by using Light weight Concrete slab there is reduction in reinforcement due to which there is reduction in overall cost of the building.