A comparative study of shrinkage and cracking of high-performance concrete mixtures for bridge decks.

摘要

To alleviate the deterioration of concrete structures, High-Performance Concrete (HPC) is extensively used, particularly for bridge decks, due to its favorable durability characteristics. However, there is a problem with the high cracking tendency of HPC due to its high early shrinkage, low water-cementitious ratio, brittleness and low creep. Thus, the HPC advantages of high compressive strength and low permeability are somewhat offset by cracking problems, which reduce the service life of bridge decks. To improve this problem, the goal of this study is to modify conventional HPC mixtures with admixtures or modifiers to obtain low-cracking or no-cracking formulations using West Virginia aggregates. Using a normal concrete (NC) as a benchmark, a total of four distinct HPC mixtures were studied: conventional HPC termed Class H by the WVDOH, HPC with shrinkage reducing admixture (HPC-SRA), HPC with latex (HPC-L), and HPC with high latex content or Overlay Latex-Modified Concrete (OLMC) as used by the WVDOH. By maintaining constant aggregate-paste volume ratio, the performance of these mixtures was evaluated through a number of tests: compressive strength, split tensile strength, free shrinkage, restrained shrinkage with ring specimens at early age, cracking tendency by measuring crack onset and width, chloride permeability, and creep for a few cases. The evaluation of these tests showed that overall, the performance of OLMC and HPC-L was best in terms of strength, chloride permeability, and shrinkage and cracking. This study will provide better focus to continued in-depth research into mixture optimization to achieve nearly crack-free HPC mixtures under field restrained shrinkage conditions.