详情

原文传递 Evaluation of Concrete Bridge Mix Designs for Control of Cracking, Phase I.

题名：	Evaluation of Concrete Bridge Mix Designs for Control of Cracking, Phase I.
关键词：	Aggregates; Bridge Decks; Concrete Construction; Concrete Mixes; Construction Materials; Cracking(fracturing); Fatigue(materials); Girder Bridges; Highway Bridges; Prestressed Concrete
摘要：	Cracking of concrete is a common problem with concrete structures such as bridge decks, pavements and bridge rail. The Agency of Transportation (VTrans) has recently invested in higher performing concrete mixes that are more impervious and has higher early strength. VTrans has also begun to standardize on bare decks on bridge rehabilitation projects. Higher strength concrete is more susceptible to cracking. With more decks being constructed with exposed concrete, the risks of chlorides and other corrosives penetrating to the reinforcing may lead to early deterioration. Additional moisture within the concrete may compound the deterioration during freezethaw periods. These stressors lead to decreased strength, which results in increased maintenance to ensure safety and durability, a reduction in the overall aesthetics of the structures and a decrease in public confidence and support. With closer attention made to the concrete mix by the addition of key admixtures, concrete may be able to perform as desired with fewer resulting problems. With 22 different concrete mix designs produced and tested for various concrete properties, flexural and compressive strength, rapid chloride permeability and shrinkage, it is clear that there are seven candidate designs, given the measured data, which could outperform current VTrans standards. To ensure successful performance of new mix designs, further testing on each, with additional refining, a second phase of this project has been approved, with the same testing parameters, to refine the chosen mix designs further. The refining of designs will entail further optimization of aggregate gradations, as the industry has trended towards reporting benefits of this, lowering only cement content to achieve design strength within 10% at 28 days while other components remain unchanged in a mix, and include shrinkage control measures in most if not all mixes.
报告类型：	科技报告