Pervious concrete

About: Pervious concrete is a research topic. Over the lifetime, 2920 publications have been published within this topic receiving 27720 citations. The topic is also known as: porous concrete & permeable concrete.

Pervious Concrete Mixture Proportions for Improved Freeze-Thaw Durability

Abstract: Recent stormwater management regulations from the Environmental Protection Agency (EPA) and greater emphasis on sustainable development has increased interest in pervious pavement as a method for reducing stormwater runoff and improving stormwater quality. Pervious concrete is one of several pervious pavement systems that can be used to reduce stormwater runoff and treat stormwater on site. Pervious concrete systems have been used and are being proposed for all parts of the United States, including northern climates where severe freezing and thawing can occur. The purpose of the research is to develop pervious concrete mixtures that have sufficient porosity for stormwater infiltration along with desirable porosity, strength, and freeze-thaw durability. In this research, concrete mixtures were developed with single-sized river gravel aggregate (4.75 mm) and constant binder contents, together with high range water reducer. River sand was used as a replacement for up to 7 % coarse aggregate. Two different types of polypropylene fibers (a shorter fibrillated variable-length and a longer fibrillated single-length) were incorporated at several addition rates from 0 to 0.1 % by volume of concrete. The engineering properties of the aggregate were evaluated along with the porosity, permeability, strength, and freeze-thaw durability of selected concrete mixtures. The results indicate that the use of sand and fibers provided beneficial effects on pervious concrete properties, including increased strength, maintained or improved permeability, and enhanced freeze-thaw resistance.

Service life model for concrete structures in chloride laden environments

Abstract: Bridges are a major element in ground transportation networks. Of the present $70 billion backlog of bridge rehabilitation needs, $28 billion dollars is attributed to the corrosion of steel in concrete. The chloride corrosion of steel in concrete structures is not confined to bridges but also reduces the service life of parking garages and sea and coastal structures. The service life model for reinforced concrete structures in chloride laden environments consists of the following serial phases: diffusion to the depth of the steel that would precipitate first maintenance actions; corrosion of the steel at the first maintenance depth until cracking and spalling occurs; and continue spalling until a damage level is reached which is defined as the end-of-functional service life for an element or structure. The diffusion phase is described by Fick's Law and the boundary conditions define the solution form. The time-to-cracking model is dependent upon factors as concrete strength properties, cover depth, and corrosion rate. Corrosion rate has a significant influence on the time-to-cracking, which typically occurs 3-7 years after initiation. The utility of the model in estimating the service life of corrosion protection systems as increased cover depth, corrosion inhibitors, and low permeable concrete is presented. As is the means for determining the time-to-first maintenance and annual maintenance requirements to the end-of-functional service life. The model in conjunction with a life-cycle cost model will enable the selection of the least cost solution to corrosion protection.