Mechanical Resistance of Cracked Mass Concrete Repaired by Grouting: Experimental Study

To evaluate the modulus of rupture and the shear strength of mass concrete repaired by grout injection, six 400 x 400 x 1250 mm (16 x 16 x 49.2 in.) concrete specimens with a maximum aggregate size of 100 mm (4 in.) were tested following ASTM C78, third-point bending test, and a loading configuration promoting large shear stresses along a vertical failure plane. ASTM C78 was performed on all virgin specimens and on repaired specimens (two repaired once and two repaired multiple times) using two different microfine injection grout mixtures with water-cement ratios (w/c) of 1.0 and 0.5. The shear test was done on two single-repaired and two multiple-repaired specimens with both grout mixtures. An average indirect tensile strength of 2.8 MPa (406 psi) was obtained for virgin specimens. This value was reduced to 1 and 0.5 MPa (145 and 72.5 psi) for specimens repaired using grout with a w/c equal to 0.5 and 1.0, respectively, regardless of the number of repairs. The shear strength of the specimens is affected by both the w/c of the injection grouts and the repaired crack width.