Estimation of concrete strength by using small size cylinders

To estimate a structural concrete strength in the seismic evaluation of a building, some cylindrical concrete cores of about a diameter of 100mm are usually gathered and compressive tests are done on them. The collection parts are limited to either walls or slabs, because it may be difficult to gather test pieces from a constructionally important member like a column by cutting off the internal steel reinforcements. This study discusses an estimation method of compressive strength by using small size cylinders of concrete cores gathered from parts without steel reinforcements instead of those of standard size cylinders. A value close to that of compressive strength given by a standard concrete core can be estimated by excluding the data at a large rotation angle under the peak load, even though compressive strength varies widely when small size cylinders are used