Mechanical resistance of cracked dam mass concrete repaired by grouting: An 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 concrete specimens with a maximum aggregate size of 100 mm were tested following ASTM C78 and a loading configuration promoting large shear stresses along a vertical failure plane. ASTM C78 was done on the all virgin specimens and on repaired specimens (two repaired once and two repaired multiple times) using two different micro fine injection grout mixes with water cement ratio (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 mixes. Average indirect tensile strength of 2.8 MPa was obtained for virgin specimens. This value was reduced to 1 MPa and 0.5 MPa for specimens repaired using grout with a w/c ratio respectively equal to 0.5 and 1.0 regardless of the number of repairs. The shear strength of the specimens is affected by both the injection grouts w/c ratio and the repaired crack width.;Keywords: mass concrete; grout injection; crack repair; modulus of rupture; tensile resistance; shear resistance; dam; large aggregate concrete.