01334139

Component

Due to an increased interconnected air voids network, pervious concrete allows water to rapidly pass through its structure. This open structure gives pervious concrete the added possibility to be applied in engineering structures as a water drainage layer, as a noise absorbing barrier or as a thermal insulation component. Open concrete could thus be employed in multi-disciplinary functions to help mitigate some of the Urban Heat Island effect. Additionally, the reduction of water-run-off due to the open structure lowers significantly the burden on the in place drainage system, reduces potential flood risks and provides improved growing conditions for nearby vegetation by directly recharging the groundwater. Despite these significant advantages, pervious concrete has not yet found wide application. To investigate the properties of pervious concrete, a fine and a coarse mixture with aggregates between 8-10 mm and 16-20 mm were made. Their hydraulic conductivity and compressive strength were measured as a function of days in a water-bath. The strength degradation was contributed to calcium leaching from the thin mortar films that were in direct contact with water due to the open structure of the concrete mixture. To investigate the actual process of leaching of the calcium and its effect on the mechanical response, the two mixtures were scanned with an X-Ray CT scanner. Specialized software was used to generate the 3D structure of the mixture from the 2D pixel-based scans, and turn them into finite element meshes. Detailed analyses of the coupled damage of leaching and mechanical softening were made, representing the mixture materials with energy based models, in which the important parameters were varied to investigate their influence. The micro-mechanical analyses allowed for a detailed observation of the behavior of the individual components within the mixture and compare the effect of the morphology of the two mixtures with respect to their overall response. From the research it was found that, to optimize the use of pervious concrete to enhance sustainability of pavements, it can be recommended to choose a smaller nominal aggregates size, to promote a thicker mortar film and a better distribution of air voids. This ensures a better overall long-term mixture response and a more global mixture failure which can be better designed for.

The DVD lists the title of this paper as: Application of Pervious Concrete for Sustainable Pavements: Micromechanical Investigation.

01329018

11-0695

English

20p

2011

Transportation Research Board 90th Annual Meeting

DVD

Figures; Photos; References (23)

Admixtures; Air voids; Concrete pavements; Degradation (Hydrology); Drainage; Groundwater recharge; Heat islands; Leaching; Permeability; Runoff

Micromechanical behavior; Pervious pavements; Sustainable pavements

Highways; Materials; Pavements; I32: Concrete

Transportation Research Board Annual Meeting 2011 Paper #11-0695

TRIS, TRB

Feb 17 2011 5:32PM