Freezing and thawing tests of grout pocket assemblies as used at welded joints of precast concrete panels

Abstract

Five specimens representing grout pocket assemblies used to protect welded joints in precast concrete panels were subjected to 250 cycles of freezing and thawing in order to determine the effectiveness of epoxy/Thiokol adhesives when applied to the surfaces of grout pockets prior to grouting. The specimens of plain concrete were cast in two halves and were 14-by 14-by 2 5/8 in. in size when placed together. The resulting grout pocket was 8 1/4 in. square at the top surface and 1 5/8 in. deep. The sides of the pockets were cast at an angle of 45°w ith the horizontal so that the bottom of the pocket was a 5 in. square. The sides and bottom of four of the specimens were coated with various epoxy/ Thiokol adhesive compounds just prior to grouting.The fifth specimen was used as a control specimen and was not coated. The specimens were frozen in air at a temperature of 2 ± 1°F, and were thawed in a water bath at a temperature of 77 ± 1°F. The control specimen failed after 96 cycles of freezing and thawing while no visible damage was apparent in the coated specimens after 250 cycles. These results clearly indicate that the use of epoxy/Thiokol adhesive mixtures significantly increases the durability of grout pocket assemblies by improving the bond between the grout and the hardened concrete.