Comprehensive Estimation of Expansive Energy Produced by Expansive Admixture and Static Expansive Demolition Agent

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Compressive strength and Young's modulus of uniaxially restrained expansive concrete began to decrease due to an excessive expansion when an unit content of expansive admixture was over 60kg/m^3. A phenomenon of anisotropic behaviors of mechanical properties in expansive concrete was observed. Addition of steel fibers in expansive concrete was effective to alleviate deterioration of the properties.When the expansive concrete was restrained radially by an outside placed steel pipe, the compressive strength and Young's modulus was respectively retained the same as one of ordinary concrete even when the unit content of expansive admixture was 90kg/m^3.The effect of chemical press on the mechanical properties of expansive concrete was scarcely anticipated even if the steel pipe was provided to restrain a radial expansion. Only in the case of triaxial restraint, the effect of chemical press was clearly observed. The chemical press effect was also observed up to the age of three years.Two steel pipes with different diameter and thickness were arranged concentrically. The expansive concrete was placed between the outside and inside pipes. Expansive strains were measured under the restraint of these pipes. The radial work done by expansive concrete on steel pipes can be assumed to be constant regardless of an arrangement and an amount of steel pipes. The longitudinal work was smaller than the radial one due to a less restraint of expansive energy by a bond between steel pipe and expansive concrete.Measurements of expansive energy of a grout with static expansive demolition agent were found difficult due to a rapid rise of temperature in the grout.