Production and Properties of Foamed Concrete Containing Waste Plastic as Aggregate: Statistical Approach

Abstract

Foamed concrete is one of the types of lightweight concrete that is used for several purposes due to its light weight. Using a statistical program in reducing the number of experimental mixtures is well known approach to reduce time and cost, as well as to compare the effect of more than one variable at the same time. In this study, Minitab software was used for the purpose of choosing the number of experimental mixtures for purpose of this investigation based on mix ingredients variables. Crushed plastic of washing machines was used as an alternative to sand as volume proportion.Using above variables, Minitab software was utilized to choose mixtures through analyzed using the response surface method. The number of experimental mixtures that were carried out on the foamed concrete was obtained by the Minitab program as 31 mixes. Tests of density, compressive strength and splitting tensile strength were conducted on the 31mixes at the age of 28 days. Several cases were applied to obtain the optimal mixes. Three optimal in addition to the conventional mix were examined. Tests such as dry density, consistency, porosity, water absorption, capillary absorption, shrinkage, compressive strength, splitting tensile strength and thermal conductivity were carried out. A remarkable reduction in the dry density for Mix 4 by about 24% was noticed with using waste plastic as fine and coarse aggregate leading to gain not only environmental benefits but also thermal insulation advantages. With achieving minimum strength reduction and maximum density reduction, a statistical approach was used successfully to propose a regression model of strength and density with ingredients of foamed concrete mix containing waste plastic as fine and/or coarse aggregate. The same strength value of conventional foamed concrete mix was achieved by adding fly ash to the mix with waste plastic as aggregate. The lowest decrease in strength and the highest decrease in density was obtained by incorporating 20% fine waste plastic and 70% coarse waste plastic at the same time.