In urbanized regions of Ontario, the road construction industry faces a number of challenges due to the growing scarcity of locally-sourced natural aggregate materials and increased restrictions on the approval and development of new aggregate extraction sites. In an effort to maintain sustainable, efficient and economical sources of construction aggregates, companies are increasingly seeking to supplement or replace natural aggregates with available artificial materials such as crushed reclaimed concrete aggregate (RCA) and reclaimed asphalt pavement (RAP).
Currently, Ontario Provincial Standard Specification (OPSS) 1010 permits the use of processed reclaimed construction materials in a variety of road base, subbase and asphaltic concrete layers, with the exception of Granular B Type II, which is a higher-performance subbase specification that solely allows primary materials produced from crushed bedrock. Consequently, there is a need to better understand the performance of reclaimed materials as alternative aggregates in Granular B Type II.
This paper focuses on a laboratory testing program which examined five different aggregate blends conforming to Granular B Type II gradation requirements which vary in composition from 100% natural crushed rock to 100% processed reclaimed material. The granular materials in the study were sampled before and after construction of test pads at two job sites in Ontario. These samples were analyzed via sieve gradation, standard and modified Proctor, permeability, California Bearing Ratio (CBR) and resilient modulus (MR) test procedures. The testing results indicate that RCA and RAP can be successfully utilized as aggregate materials in Granular B Type II subbase applications.
