TESTS OF HOLDING STRENGTH OF FORM ANCHORS EMBEDDED IN CONCRETE PLACED AND CAST AT REDUCED TEMPERATURES.

Tests were made to determine the shear resistance or holding strength of form anchors placed in concrete mixed and cured at reduced temperatures 45-50 F. Four mass 6-in. maximum size aggregate concrete blocks were cast and cured in a temperature-controlled room, and six 18-in. and sixteen 24-in. form anchors were embedded in the blocks and tested at an age of 72 plus or minus 4 hours. One of the blocks contained a 30 per cent replacement by solid volume of the portland cement with fly ash. The results indicate that adequately designed anchors of either length will, under the test conditions used, provided resistance at 3 days age in excess of normally expected loads even though the concrete has a cement content as low as 2.5 bags per cu yd and is placed and cured at reduced temperatures. The use of fly ash as a replacement material reduced the holding power of the anchors appreciably, but not below a safe level. Author