Potential Technical and Cost Benefits of Two-Lift Concrete Paving

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 local aggregates that might not be suitable for conventional concrete pavement but also provides opportunities for incorporating recycled materials and higher levels of supplemental cementitious materials to produce an economical and sustainable pavement. More importantly, the practice can also produce more durable concrete pavements for either airfield or highway applications through the optimization of top lift mixture design, as well as with desirable surface characteristics including improved skid resistance and reduced noise. The presentation discussed the potential technical benefits of 2LCP. While 2LCP is likely to result in increased construction costs associated with additional equipment, labor, and scheduling effort, potential savings from the use of lower-quality, less expensive concrete and aggregate in the bottom lift could be sufficient to offset the additional costs. According to cost information collected from recently constructed 2LCP projects in the United States, a case-based cost analysis was also performed to evaluate the cost-effectiveness of the 2LCP practice. Through information collected from an extensive literature review, surveys, and interviews, a summary of the benefits of 2LCP from technical and cost-effectiveness perspectives was provided to justify the implementation of the 2LCP concept.