This research was funded by the National Institute for Transportation and Communities, or NITC, a program of TREC at Portland State University. Funding was also provided by Oregon State University and the University of Wyoming.
Concrete Testing -- Recycling, Concrete -- Transportation, Recycled materials
Making concrete out of recycled concrete aggregate, or RCA, can be a sustainable and cost-saving alternative to other aggregates. However, the quality of concrete made with RCA is dependent on the quality of the recycled material used. OTREC researchers Jason Ideker of Oregon State University and Jennifer Tanner of the University of Wyoming, with graduate student researchers Matthew P. Adams and Angela Jones, sought to determine some of the primary concerns involved with the use of RCA and to arrive at methods of assessing its durability for use in new concrete.
Alkali-silica reaction occurs in concrete over time, causing it to expand and eventually weaken. There are standards for testing aggregate to determine its susceptibility to this reaction, but these testing standards were developed for traditional aggregates, not for RCA. Phase 1 of this research project involved accelerated laboratory tests related to assessing alkali-silica reactivity (ASR) of RCA. A team of four laboratories performed testing using the same materials in order to determine the variation between different laboratories. Phase II of the research sought to provide corroboration of those results by testing an additional three aggregates in two laboratories. In addition, field specimens and mitigation studies were conducted. There are methods to control ASR in concrete which contains traditional aggregates; another goal of this research was to investigate how effective those methods are in concrete incorporating RCA.
Ideker, Jason H. Making Concrete from Recycled Materials. 2011-425. Portland, OR: Transportation Research and Education Center (TREC), 2014.