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Showing 1-5 of 8 Abstracts search results

Document: 

SP282

Date: 

December 29, 2011

Author(s):

Editor: Charles A. Weiss, Jr.

Publication:

Symposium Papers

Volume:

282

Abstract:

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.

DOI:

10.14359/51683563


Document: 

SP282-01

Date: 

December 27, 2011

Author(s):

Heather Brown, John Tyner, Ryan Otter, Spring Gilson, Jessie Weatherly and Brent Pilon

Publication:

Symposium Papers

Volume:

282

Abstract:

Note: This document has been retracted by request of the authors and is no longer available.

DOI:

10.14359/51683638


Document: 

SP282-03

Date: 

December 27, 2011

Author(s):

Jonathan Thomle and Liv Haselbach

Publication:

Symposium Papers

Volume:

282

Abstract:

The focus of this study is on the pH changes over time of water in contact with pervious concrete aged under varying ambient air restrictions. Elevated pH levels may be a concern if exfiltrated directly to sensitive waters. This study was conducted to aid designers by determining the rate of pH decline under various conditions. For this study laboratory prepared pervious concrete specimens exposed to three different levels of ambient air were periodically tested for pH using four different testing methods, infiltrating either deionized water or tap water through the specimens, or soaking the specimens in either deionized water or tap water. Obvious trends in pH decline were observed. Greater exposure to ambient air significantly increased the rate of pH decline. The tap water tests represented more typical stormwaters and had much lower pH readings than the deionized water tests. The samples were representative of typical in-place conditions in an arid environment with little buffering and yet the pH declined sufficiently in well under a year.

DOI:

10.14359/51683640


Document: 

SP282-02

Date: 

December 27, 2011

Author(s):

Norbert Delatte

Publication:

Symposium Papers

Volume:

282

Abstract:

Portland Cement Pervious Concrete (PCPC) is a material of increasing interest for parking lots and other applications. PCPC typically consists of coarse aggregates, portland cement, water, and various admixtures. In this research, in-service PCPC pavements were inspected in the field, and cores were removed in order to investigate properties in the laboratory. Field evaluation methods included visual inspection, two surface drainage measurements, and indirect transmission ultrasonic pulse velocity (UPV). Laboratory testing methods included void ratio, unit weight, compressive strength, splitting tensile strength, hydraulic conductivity, and direct transmission UPV. Because it is compacted on the surface with screeds or rollers, PCPC generally has higher strength, lower void ratio, and lower hydraulic conductivity at the surface than at the bottom. Therefore, the properties of the tops and bottoms of core samples were compared. Generally, the PCPC installations evaluated under this research project have performed well in freeze-thaw environments with little maintenance required. No visual indicators of freeze-thaw damage were observed. With the exception of some installations where the pore structure was sealed during construction with wet mixtures or over compaction, nearly all sites showed fair to good infiltration capability based on drain time measurements.

DOI:

10.14359/51683639


Document: 

SP282-05

Date: 

December 27, 2011

Author(s):

Omkar Deo, Milani S. Sumanasooriya, and Narayanan Neithalath

Publication:

Symposium Papers

Volume:

282

Abstract:

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.

DOI:

10.14359/51683642


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