Nanoengineered concrete with coloidal sílica for repair of concrete structures

Abstract

Pathological manifestations in concrete structures result from failures in design, execution, maintenance, or material degradation, thus requiring effective repair solutions towards extending the structures’ service life. Nanoengineered concrete with colloidal silica can be an efficient alternative as a repair material, for it reduces porosity and increases mechanical strength due to its effect on the interfacial transition zone between the aggregate and the cement paste. This study evaluates the application of a high-strength concrete with colloidal silica as a repair material to conventional concrete structural elements. Cylindrical and prismatic concrete specimens were produced, intentionally damaged, and subsequently repaired with the developed special concrete. Characterization results revealed significant improvement in the mechanical properties of the special concrete even at low colloidal silica contents, being the best compressive strength obtained with the addition of only 1% colloidal silica, by cement mass. The repaired elements showed satisfactory performance in all measured properties, maintaining compressive strength values statistically similar to those of intact conventional concrete after 28 days of repair (39.4 MPa and 40.7 MPa for repaired and intact specimens, respectively). The results highlight the potential of nanoengineered concrete with colloidal silica addition for practical structural repair applications.