1. Three simple tests for selecting low-crack cement
- Author
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Burrows, R.W., Kepler, W.F., Hurcomb, D., Schaffer, J., and Sellers, J.G.
- Subjects
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PORTLAND cement , *EVAPORATION (Chemistry) , *CRACKING process (Petroleum industry) - Abstract
On projects involving restrained concrete such as bridge decks, the risk of cracking can be reduced by selecting low-crack Portland cement as was done with the Rudolphstein Bridge in Bavaria. A test, RILEM TC 119 TCE 3, was used to establish the cracking risk from thermal contraction and autogenous shrinkage [ACI Monograph 11 (1998)]. No equivalent ASTM test exists. The new drying shrinkage cracking test, AASHTO 34 98 is not directly applicable to the early-age cracking problem in bridge decks as this cracking is caused by thermal contraction and autogenous shrinkage.This paper presents two methods, much simpler than the RILEM test, for estimating the cracking tendency of Portland cement: a 12-h semi-adiabatic compressive strength test, and a 12-h chemical shrinkage test. A simple drying shrinkage test using cement paste is also discussed.It is concluded that the strength test and the chemical shrinkage test measures the thermal cracking tendency of Portland cement and can be used to select low-crack Portland cement for important projects involving restrained concrete. The tests, particularly, the chemical shrinkage test, should be considered for inclusion in the Standard Performance Specification for Hydraulic Cement, ASTM C 1157. This is important because the United States is experiencing more cracking problems than in some other countries such as Germany where it has been reported that bridge deck cracking is not a problem [ACI Monograph 11 (1998)]. They have coarser cements and limit the cement content. [Copyright &y& Elsevier]
- Published
- 2004
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