详情

High-Performance Stress-Relaxing Cementitious Composites for Crack Free Pavements and Transportation Structures

项目名称：	High-Performance Stress-Relaxing Cementitious Composites for Crack Free Pavements and Transportation Structures
摘要：	Concrete transportation structures are subject to cracking that leads to deterioration--corrosion, weakening due to sulfate attack, and damage from alkali-silica reactivity. These problems shorten the service lives of bridges, tunnels, and pavements and reduce their level of performance. The goal of this EAR project is to design concretes with increased resistance to cracking. Paradoxically, one method proposed introduces controlled cracking on a nano to micrometer scale to lower the tensile stresses in concrete to a level where they will not cause macroscale cracking or curling. This relaxation would be induced by utilizing stress-relaxing cementitious composites (SRCCs), which are achieved by embedding nano to micrometer scale inclusions that reduce the concrete's brittleness without sacrificing its strength. Previous attempts to limit cracking have focused mainly on cracking caused by shrinkage and have included reducing the water-to-cementitious-materials ratio, using mineral admixtures, and adding shrinkage-reducing admixtures. The SRCC approach in this project, however, will address not only cracks caused by shrinkage but also those related to thermal changes, expansive corrosion reactions, ASR expansions, and other causes. To maximize the prospects of success, the Exploratory Advanced Research (EAR) Program study will investigate SRCCs on two scales, using two models. On the nano to micrometer scale, materials being explored include surface-treated carbon nanotubes, silica fume, metakaolin, fly ash, limestone powder, and rice husk ash. The stress-relaxation effect of these materials occurs as nano (or micro) cracks form at the interface of the cement paste matrix molecules and the embedded SRCC molecules, releasing energy. After crack formation, further relaxation results from sliding friction at the interface. On the micrometer to millimeter scale, various types of waste plastic are being investigated for their ability to increase concrete's visco-elasticity. Should this method prove successful and be widely adopted, it could benefit the environment tremendously. Plastics occupy about 25 percent of the total volume of landfills, and their manufacture consumes about 10 percent of the country's total fossil fuel use. Only 5 percent of plastics produced in the United States are now recycled.
状态：	Active
资金：	0.00
资助组织：	Federal Highway Administration
执行机构：	Texas A&M Research Foundation, College Station
开始时间：	20080220
实际结束时间：	20100220
主题领域：	Bridges and other structures；Highways