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Abstract: The restrained ring test is becoming widely used as a standard test method to assess the potential for early-age cracking in concrete mixtures. Previous research focused on the development of analytical solutions for quantifying residual stress development in restrained ring specimens that either assumed that the ring was thin (i.e., a thin wall approximation) or that the shrinkage was uniform along the radial direction for a thick-walled ring. This paper presents an analytical solution to consider the influence of moisture gradients that occur when a thick-walled ring specimen dries from the outer circumference. Toward this end, the ring that dries from the outer circumference is treated as the superposition of a stress field that is caused by external restraint and a stress field that arises due to differential shrinkage. An analytical expression is presented to estimate the stress components. To assess the suitability of the analytical solution, it was compared with results from a finite element analysis and a reasonably good agreement was observed. [Copyright &y& Elsevier]

Strain rate-dependent shear behavior of ultra-high-performance fiber-reinforced concretes (UHPFRCs) with confining pressure was investigated using a new shear test setup in an improved strain energy impact machine (I-SEFIM). Different confining pressures were applied to the specimens prior to shear testing at both static and high strain rates, and were maintained during testing. The shear strength of UHPFRCs was highly sensitive to the applied strain rate and confining pressure. The effect of confining pressure on the shear strength was more pronounced at a static rate rather than at high strain rates. Strain rate-dependent shear failure surfaces of UHPFRCs were proposed. [ABSTRACT FROM AUTHOR]