International Concrete Abstracts Portal

SP-282 This CD-ROM contains seven papers that were presented at sessions sponsored by ACI Committee 522 at the ACI Fall 2009 Convention in New Orleans, LA. The aim of this SP is to present some of the latest research findings on pervious concrete and to provide state-of-the-art examples on the use of pervious concrete. The six papers in this SP present the latest research results from both experimental and numerical studies on various aspects of pervious concrete.

One of the key concerns with pervious concrete is the material’s surface durability, specifically resistance to raveling. As the market for pervious concrete grew, this was one of the hurdles to broader adoption of the technology. This paper documents the process of developing a test method to determine the potential raveling resistance of a pervious concrete mixture. The process included a study with lab cast cylinders to compare the raveling resistance potential of pervious concrete mixtures using different aggregates, varying cement contents, and basic chemical admixtures. A refined procedure of the test method was developed after an unsuccessful ASTM round robin evaluation. The results from this new method will provide the industry with beginning correlations between basic mix ingredients and the surface durability of a finished pervious concrete pavement.

Frost damage can be a significant problem for pervious concrete structures in the cold climate. Various damage mechanisms have been developed to explain the frost damage in conventional concretes. However, limited studies have been attempted to correlate these mechanisms with pervious concretes. This paper reviews the physical aspects of frost damage and the main factors (e.g. the degree of saturation, the permeability of paste, the length of flow path, and the rate of freezing) that contribute to the deterioration of concrete upon freezing with the goal of using these mechanisms to explain the experimental observations obtained from the pervious concrete. This paper also compares the differences in freeze and thaw deterioration between pervious and conventional concretes. A variety of test results from different pervious concrete mixtures and construction practices are analyzed, which would aide in identifying the optimal mixture design and construction procedures to achieve durable pervious concrete structures.

This paper presents the results of studies conducted to develop a self-consolidating Portland Cement Pervious Concrete (PCPC) for overlay applications to reduce roadway noise, reduce splash and spray, and to improve friction as a surface wearing course. A variety of mixture variables were characterized for workability to develop a mixture for mechanized placement. During the fall of 2008, a 100 mm (4 in.) thick pervious concrete overlay on traditional concrete was constructed at a test facility. Construction is described as well as results of field tests to characterize the condition of the pavement seven months following construction. Performance testing of the overlay section included bond strength, permeability, skid resistance, and noise generation. The results of these studies show that effective PCPC overlays can be designed for wearing course applications.

Properties of a random porous material such as pervious concrete are strongly dependent on its pore structure features. This study describes the development of different models to understand the material structure – property relationships in pervious concretes. Several pervious concrete mixtures with different pore structure features are proportioned. The pore structure features such as pore area fractions, pore sizes, mean free spacing of the pores, specific surface area, and the three-dimensional pore distribution density are extracted using image analysis methods. The performance features modeled as a function of the pore structure features are: (1) the unconfined compressive strength, (2) permeability, and (3) permeability reduction due to particle trapping in the pores (clogging). A statistical model is used to relate the compressive strength to the relevant pore structure features, which is then used as a base model in a Monte-Carlo simulation for feature sensitivity evaluation. Permeability prediction is accomplished using the well-known Katz-Thompson equation that employs the pore structure features. An idealized 3-D geometry obtained from 2-D planar images of pervious concrete sections is used along with a probablistic particle capture model to predict the particle retention associated with clogging material addition and simulated runoff. These models are anticipated to be useful in designing pervious concrete systems of desired pore structure for requisite performance.