Placement of Low-Slump Concrete: Fid-Bau Portal

Placement of Low-Slump Concrete

H. C. Ozyildirim

Investigated were the field conditions necessary for achieving dense, impervious, good quality, low-slump concrete that would provide long-lasting overlays for bridge decks. The parameters considered were consolidation, texturing, bonding, freezing and thawing durability, and permeability. In a low-slump overlay consolidated by a vibratory screed, a comparatively large number of coarse voids were observed. Specimens consolidated manually by rodding and vigorous tapping exhibited better consolidation than those compacted by mechanical vibrators. However, the permeability studies indicated that even though the low-slump concretes had more coarse voids than desired, they can provide a resistance to the penetration of chlorides ccmparable to that provided by ordinary bridge deck concretes of good quality. A satisfactory bond was achieved between the bottom course of the deck and the overlay without the use of grout or slurry at the interface. A metal roller provided the proper surface texture for these stiff concretes. The freezing and thawing resistance of low-slump, air entrained mixtures was satisfactory, but local popouts could be expected.