Size and Wall Effects on Compressive Strength of Concretes

作者：Turkel Aziz; Ozkul M Hulusi

来源：ACI Materials Journal, 2010, 107(4): 372-379.

• compressive strength
• concrete cores
• cutting damage
• drilling damage
• high-strength concrete
• maximum aggregate size
• size effect
• wall effect

This study aims to eliminate the wall effect experienced in molded specimens by either sawing or drilling them out of concrete blocks. For this purpose, the concrete blocks were prepared in four different thicknesses: 50, 100, 150, and 200 mm (2, 4, 6, and 8 in.) and in two different strength classes: moderate and high. The maximum sizes of the aggregates used in the concretes were 12, 22, and 31.5 mm (0.47, 0.87, and 1.24 in.) for each concrete class. The cubic and core specimens were sawn or drilled out of concrete blocks with an equal length or diameter to the thickness of blocks. The damage that occurred during sawing or drilling was related to the maximum aggregate size of the concrete and, by using the size effect law, the damage was predicted. After eliminating the wall effect and the damage of sawing or drilling, it was observed that a considerable size effect exists between the specimens tested.