Field measurements for early-age strains in concrete walls Available to Purchase

Temperature changes and in-plane movements at early age in 12 reinforced concrete walls are reported. Between 14 and 37 vibrating wire strain gauges were placed in eleven of the walls. Temperatures were monitored at each gauge location. Gauges were placed mid-way through the wall thickness. In-plane residual (‘restrained’) strains were deduced from restraints applied to free in-plane movement of the cooling concrete in various parts of the wall. Restraint to free movement is provided externally by previously cast elements such as a wall foundation, combined with internal effects arising from the considerable variation in peak temperatures from place to place in a wall. At their tops, it is found that walls are in compression after cooling. In other parts, the tension is not usually very high, although a restraint factor of 0·5 to free horizontal movement is approached locally in some walls and a high diagonal strain > 200 microstrains was estimated in two of the walls.