Self-compacting micro concrete in structural strengthening: application as a bond bridge

ABSTRACT

The objective of this work was to evaluate the efficiency of a micro concrete for structural strengthening, as an adhesion bridge between old and new concrete. Contributing to environmental preservation, the replacement of sand with a filler, a by-product of crushing stones, was evaluated based on a reference mixture. The binders used were Portland cement (85%) and silica fume (15%). The water/binder ratio and the proportion between cement and silica fume were obtained experimentally, maximizing the use of the superplasticizer additive, and obtaining acceptable conditions of self-compacting of the mixtures. The properties of micro concrete in the fresh and hardened state were evaluated, in addition to the adhesion provided by the micro concrete on concrete substrates and as an adherent material between old and new concrete, simulating a situation of structural reinforcement. As a result, good MC self-compacting properties were obtained, with an increase of 26% in scattering and 5% in MC flow time with 15% replacement in relation to the reference MC. There was also considerable gain in the physical properties of the mixtures. Still, for 15% replacement, there was an increase of 18% in the modulus of elasticity and a reduction of almost 9% in the total water absorption. Good adhesion results were also obtained on concrete substrates, demonstrated by the cohesive failure observed in the adhesion test. In addition, in a situation of structural repair, the material proved to be satisfactory for use as an adhesion bridge between old and new concrete.

Keywords
Structural strengthening; Sustainability; micro concrete; slant shear test