Concrete to Bedrock Bond Testing by Jacking from Bottom of a Bore Hole

Abstract

A low cost in situ method of testing the bond between concrete and bedrock is described. The test can be performed in exploration bore holes as part of a detailed site investigation.A hydraulic jack is placed at the bottom of a specially prepared bore hole and a concrete plug cast above it. After the concrete has cured, pressure is applied to the jack until the concrete plug slips. Bond stress is computed by dividing the applied load by the peripheral area of the plug.The test provides realistic bond values for the design of rock sockets as well as useful information for the bidding contractors.