The Effect of Slurry Type on Drilled Shaft Cover Quality-Paper

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The study investigates how slurry type affects concrete cover quality in tremie-placed drilled shafts. Rather than rising uniformly, concrete first fills part of the reinforcement cage and then flows outward toward the shaft surface. This radial flow can create laitance-filled channels that mirror the cage, potentially affecting cover thickness, strength, and corrosion resistance.<br /><br />Researchers tested 24 laboratory shafts constructed with bentonite, polymer, or natural slurry. They assessed surface texture, corrosion potential, and strength distribution. Shafts cast with bentonite showed a clear association with laitance-channel formation, along with greater corrosion potential and lower strength. Polymer-cast shafts behaved similarly to water-cast shafts, with no comparable increase in corrosion risk or reduction in strength.<br /><br />The results suggest that slurry type can significantly influence drilled-shaft cover quality, with bentonite presenting greater potential for adverse effects.

Keywords

drilled shafts

concrete cover quality

tremie placement

slurry type

bentonite slurry

polymer slurry

laitance channels

corrosion resistance

reinforcement cage

strength distribution