Abstract

Researchers conducted an extensive literature search, survey of TxDOT districts, and survey of other state Departments of Transportation (DOTs) to determine the state of the art for bridge deck curing, early loading, early age behavior, and durability prediction models. Several concrete mixtures commonly used in regional districts throughout the state of Texas were tested. Each concrete mixture was tested under field conditions within its respective climatic region. Field testing and testing of field collected samples provided information on concrete strength, concrete maturity and permeability. Supplementary laboratory experiments were performed to determine permeability using the salt ponding method, and the rapid chloride penetration test, RCPT. Researchers used the laboratory tests to correlate results with field collected samples and concrete strengths. Both field and laboratory test data were compared with existing models for predicting concrete maturity for various mix designs and curing methods. Core samples from field sites were examined using petrographic techniques to determine air void contents, calcium hydroxide formation, aggregate/paste interface features, cracks, unhydrated cement grains and other petrographic features. Researchers related the variations of petrographic features with wet mat curing duration. Finally, researchers investigated the fracture properties of several medium-strength concrete mixes cured for various durations in order to characterize the extent of cracking that might allow the ingress of chlorides from de-icing salts to the reinforcing bars. The purpose of this report is to present an overview of the research project and a summary of significant findings from the research.

Project PI: Phillip T. Nash

Project C0-PI: Sanjaya Senadheera

Survey Results

Literature Review

Rapid Chloride permeability and Ponding Tests

Compressive Strength, Maturity and Strength
Durability Index (SDI)

Fracture, Flexural Strength and Shrinkage

executive summary