Repair material properties which influence long-term performance of concrete structures

The paper presents the results of an experimental investigation to determine some typical properties of three commercially available generic repair materials, which are of significance to the subsequent structural behaviour of repaired concrete members. it also compares the performance of these materials with plain concrete mixes of similar strength and stiffness, which are also suitable for repair applications. Data on strength, stiffness, shrinkage and creep under different temperature and humidity exposure are presented. in addition, water permeability coefficients of the materials have been determined. The results show that shrinkage of the repair materials is significantly greater than shrinkage of normal concrete. The shrinkage of the specially formulated repair mortars, especially those modified with a polymer admixture, is very sensitive to relative humidity of exposure compared with normal concrete. The permeability of normal concrete is similar to that of both the high performance non-shrinkable repair material and the polymer modified repair material. The other repair material based on a mineral cement binder is more permeable than normal concrete. The inclusion of aggregates improves the mechanical properties and dimensional stability of repair materials.