R. C. DE VEKEY Building Research Establishment

BS5628:Part 2 covering the design of reinforced and prestressed masonry allows the use of concrete and grout infill in small prismatic voids in concrete or brick masonry as a means of protecting carbon steel reinforcement. The paper shows that conventional concrete mixes are dewatered by the absorptive surface of the masonry ‘shuttering causing increased porosity as fissures which lead to significant reductions in the strength of the infill but not so much as to affect performance. More importantly their presence would allow rapid carbonation of the concrete thus prejudicing the durability of the structure. Alternative infill mixes are suggested in the conclusions.