Highway Uses of Crushed Concrete Materials (7-4954-S)

The production of crushed portland cement concrete (CPCC) continues to grow year by year. Currently, in excess of 100 million tons of crushed concrete are generated annually in the United States. In conjunction with the increase of this waste product, recycling of CPCC has been suggested as an attractive alternative to disposal. Consequently, many researchers and engineers have investigated the reuse of crushed concrete materials. Although CPCC contains particles of various sizes from inches to microns, most previous studies focused on the use of particles larger than the No.4 sieve size relative to the use as coarse aggregates in new concrete. Since CPCC fines passing the No.4 sieve tend to be highly absorptive and angular in nature, difficulties have been experienced in processing and using them in concrete mixtures. The Texas Department of Transportation (TxDOT) has successfully used the coarse particles of CPCC in new concrete for various purposes. However, increased concrete crushing has resulted in growing stockpiles of CPCC fines (Figure 1). It is imperative that effective and full use of crushed concrete materials including fines be found. Therefore, this research project explored potential ways of using CPCC fines associated with TxDOT applications.