Report No.: CCEER-91-4
Title: A Study of Protective Overlays for Highway Bridge Decks in Nevada, with Emphasis on Polyester-Styrene Polymer Concrete
Authors: D. N. O'Connor and M. "Saiid" Saiidi
Date: October 1991
Sponsoring Agency: Nevada Department of Transportation
Department of Civil Engineering/258
University of Nevada, Reno
Reno, NV 89557
A major problem facing state and federal highway departments is the deterioration of bridge decks due to the corrosion of reinforcing steel. Polyester-styrene polymer concrete overlays provide durable and wear-resistant surfaces for portland cement concrete bridge decks, and can be formulated to provide low water and chloride permeabilities. In order to study the effects of the composite action between the portland cement concrete deck and the polymer concrete overlay, a knowledge of the material properties of the chosen polymer must be obtained, and the compatibility of the material with portland cement concrete must be determined.
This report provides an introduction to the materials under consideration and a comparison of the engineering properties of portland cement concrete and polyester-styrene polymer concrete. Properties considered include compressive strength, modulus of elasticity, tensile strength, flexural strength, thermal expansion characteristics, rate of compressive strength gain, high temperature strength degradation, shrinkage, and creep.
The bond between the polymer concrete overlay and the portland cement concrete deck results in a composite section with distinct areas of different physical properties. Because the polyester-styrene concrete and the portland cement concrete exhibit different coefficients of thermal expansion and moduli of elasticity, composite action under temperature change raises a concern.
Two finite element models were used to determine the compatibility between the concrete bridge deck and the polyester-styrene overlay. Allowable stresses due to temperature were determined using the ACI ultimate strength method and both AASHTO service load and ultimate strength methods. Results of the analysis are presented, and an-attempt to explain any excessive stresses is made (Abstract by authors).