Mehdi S. Zarghamee

CONCRETE CREEP AND SHRINKAGE PREDICTION FROM SHORT-TERM TESTS

This paper presents a method for predicting the ultimate creep and shrinkage from the results of short-term standard creep and shrinkage tests on 15-cm-diameter cylinders. Short-term tests are defined as those performed during a time period not exceeding 28 days after exposure. The paper uses both Bazant-Panula (BP-KX) and American Concrete Institute (ACI) 209 models to predict the ultimate concrete creep and shrinkage from the short-term test results. Predictions are compared with the results of long-term creep and shrinkage tests. Results show that the accuracy of prediction of the ultimate creep and shrinkage increases significantly when short-term tests results are used to adjust the models. Relative to both test-adjusted BP-KX and ACI model predictions, the coefficient of variation of long-term measured shrinkage strains is less than 20 percent, and the coefficient of variation of long-term measured instantaneous plus creep strains is typically less than 7 percent.

Analysis and Performance of PCCP Mortar Coating

The aggressive nature of the soil surrounding prestressed concrete cylinder pipes (PCCP) has been identified as causing pipe failures related to deterioration of mortar coatings used to protect the prestressing wires. This paper presents a discussion of the degradation mechanisms and methods that can be useful for evaluating the condition of mortar coating and assessing its remaining useful life.