Limiting structural damage on masonry structures due to foundation movement

Over three million low-income houses have been built in the Republic of South Africa over the last two decades, many of which have experienced structural distress due to foundation movement or poor quality construction. The South African low-income housing sector employs a large number of entry-level material suppliers and building contractors, and this results in substantial variability of construction materials, technology and workmanship standards. Underpinning the foundation as a remedial solution to low-income houses is very expensive compared to the actual cost of the product (i.e. the house). Alternatively, it may be cost effective to demolish and rebuild the structure. In this paper, cost effective alternative to underpinning is explored using a proprietary type of reinforcement which is grouted to concrete blockwork. The reinforcement and grout act compositely with existing concrete blockwork, both to repair the cracks and to form deep reinforced masonry beams. This paper covers the initial test programme to investigate and assess the suitability of different reinforcement systems to improve the structural strength and performance of concrete blockwork walling systems. A series of tests were conducted on blockwork wall sections above window and door openings. The material specimens used for the investigation were sampled from a number of construction sites where the quality of the materials varied from site-to-site. The results of the tests showed strength enhancement of the blockwork and an improved ductility.