Field Performance Evaluation of Sustainable Aggregate By-product Applications

Research efforts at the Illinois Center for Transportation (ICT) focused on evaluating new sustainable applications of Quarry By-products (QB) or QB mixed with other marginal, virgin, or recycled aggregate materials in pavements, as unbound or chemically stabilized pavement layers. Sixteen full-scale test sections were constructed to evaluate the use of QB in base, subbase, and aggregate subgrade applications. The chemically stabilized test sections utilizing QB were stabilized with 3% cement or 10 % Class ‘C’ fly ash by dry weight and were constructed over a subgrade having an engineered unsoaked California bearing ratio (CBR) of 6% to study their effectiveness in low to medium volume flexible pavements. The unbound applications of QB investigated the use of QB to fill the voids between large aggregate subgrade rocks commonly used for rockfill applications on top of very soft subgrade soils, as well as using dense-graded aggregate subgrade layers with higher fines content up to 15% passing No. 200 sieve for soft subgrade remediation. These unbound test sections were constructed over a CBR=1% subgrade soil to investigate their effectiveness in both construction platforms and low volume road applications. All the field test sections were then evaluated in rutting and fatigue by applying traffic loading using a super-single wheel in Accelerated Pavement Testing (APT). Following APT, forensic analysis tests were conducted to further evaluate the test section performances; these tests included: Falling Weight Deflectometer (FWD) tests before and after trafficking, hot mix asphalt coring, Dynamic Cone Penetrometer (DCP) profiling of subsurface layers, and trenching to expose the cross sections of the constructed sections. In general, results from APT and forensic analyses indicated that satisfactory results and improved rutting performance were obtained from all the test sections utilizing QB applications. Therefore, the proposed QB applications are deemed to be readily implementable and can be successfully incorporated into standard pavement construction and rehabilitation practices.IDOT-R27-168Ope