Shrinkage and Creep Properties of High-Strength Concrete Up To 120 MPa

Recently, the use of high-strength concrete has become more popular due to the availability and significant variety of the admixtures. High-strength concrete increases the load carrying capacity of the columns, therefore, reduces their sizes in buildings and bridges. In bridges, high-strength concrete could result in reduction of number of girders as well as an increase in the span length which significantly reduces the complexity of a project, construction time and overall cost. Due to lack of research data for the material characteristics of high-strength concrete, most of the design codes worldwide limit the applicability of high-strength concrete for concrete structures. This paper summarizes the research findings on the shrinkage and creep behavior of high-strength concrete. A total of 42 cylindrical specimens and 18 prism specimens were monitored for one year. The variables considered in this investigation were the concrete compressive strength (70 to 120 MPa), specimen size (cylindrical or prism), curing type (moist or heat curing), age of concrete at loading (1, 7, 14, 28 days) and loading stress level (0.2f’c or 0.4f’c). The creep coefficients and shrinkage strains were obtained for the range of concrete compressive strength, evaluated and compiled with the current predictions according to the AASHTO LRFD Bridge Design Specifications. Research findings indicate that the current AASHTO LRFD Specifications could be used to estimate the creep coefficient for moist cured high-strength concrete, however, overestimates the values for heat cured high-strength concrete. The current AASHTO LRFD Specifications predict the shrinkage behavior very well, therefore, can be used to estimate the shrinkage strain of moist and heat cured high-strength concrete.