Determination of Strength Properties of Cement Concrete Utilizing Recycled Concrete Aggregates and Thickness Design of Rigid Pavement for Low Volume Road

Abstract

Recycled concrete aggregate refers to aggregate obtained from demolished concrete. It can be utilized for cement concrete production to meet rising need of huge quantities of aggregates and reduced problem of disposal of demolished concrete simultaneously. Low volume road carries average daily traffic less than 450 commercial vehicle per day.

In laboratory, properties of recycled concrete aggregate was studied and it was mixed with coarse crushed aggregate in different proportions i.e. 100%, 80%, 60%, 40%, 20%, 0% by weight to produce concrete with addition of plasticizer and microsilica. The concrete was casted and cured to perform compressive strength, split tensile strength and flexural strength tests for 7 days and 28 days concrete. Design of thickness of cement concrete pavement was done according to Guideline for Design and construction of cement concrete pavements for low volume road IRC:SP:62-2014 & Design and construction of rigid pavement for low volume roads prepared by Institute of Professional Training and Management Nepal. Cost estimation was done for construction of cement concrete pavement according to Department of Roads norms for Road and Bridge Work.   

Result showed that M30 grade concrete for low volume road can be produced with coarse recycled concrete aggregate. The compressive strength, split tensile strength, and flexural strength of concrete gets reduced with addition of recycled concrete aggregate upto 6.7%, 6.25% & 8.99% respectively as compared to crushed aggregate concrete. Design thickness of plain jointed cement concrete pavement for low volume road was developed for different value of subgrade CBR 4, 5, 6, 7, 8, 9, 10, 15, 20, 50 traffic volume 50 CVPD, 150 CVPD, 300 CVPD & 450 CVPD, Hilly/Terai region underlying granular sub-base or cementitious sub-base. Cost estimation calculation for M30 grade concrete with crushed aggregate, recycled concrete aggregate and their combination showed upto 8.5% cost saving per cubic meter concrete if recycled aggregate concrete is used.