2018 Volume 72 Issue 1 Pages 166-172
Two type methods of A and B uniaxially restrained specimens are defined by JIS A 6202. An A type method is used for measuring restrained expansion and a B type method is used to measure both restrained expansion and restrained drying shrinkage of expansive concrete. This paper discusses mainly experimental results concerning of drying shrinkage properties measured till two years after one week expansion by two type uniaxially restrained specimens and two measuring instruments. A dial gauge method was used to measure expansion and drying shrinkage according to JIS A 6202. Two marks of gauge length 200mm were also pasted on the concrete surface to measure drying shrinkage with a contact type strain-gauge. Uniaxially restrained expansion measured by the A type specimen is almost the same as the value by the B type one. Drying shrinkage measured by dial gauge is almost the same as the shrinkage by contact type strain-gauge, up to a limit value. However, beyond the limit drying shrinkage value, the shrinkage measured by contact type strain-gauge is larger than the value by dial gauge even though in the B type method with a screw threaded PC bar. It is suggested that unrestrained drying shrinkage could be measured after uniaxially restrained expansion by the A type method only with a combination of dial gauge and contact type strain-gauge.
