Two-lift concrete paving (2LCP) involves placing two layers of concrete (wet-on-wet)instead of a single homogeneous layer. The practice not only allows the use of localaggregates that might not be suitable for conventional pavement, but also providesopportunities for incorporating recycled materials and higher levels of supplementalcementitious materials (SCMs) to produce an economical and sustainable pavement. Thepractice can also produce durable pavements through the optimization of top lift mixturedesign with desirable surface characteristics including improved skid resistance andreduced noise. While 2LCP could become a viable and competitive alternative toconventional single-lift paving, challenges of 2LCP are to have the proper pavingequipment and pavement construction management, the right mixture proportions toensure the use of local materials in the bottom lift to result in an economical placementand to ensure a high quality top lift. Through information collected from an extensiveliterature review, surveys, interviews and a recently hosted 2LCP workshop, a summaryof benefits of 2LCP from sustainability and cost effectiveness perspectives was provided.Four 2LCP projects recently constructed in the U.S. were summarized as case studies.This paper also discusses additional requirements in materials, equipment andconstruction, project scheduling and jobsite management, which will be beneficial in theimplementation of 2LCP construction.
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