Deterioration of Terrazzo

Abstract

Terrazzo installation is often perceived as an art, left to individual contractors and craftsmen to implement tried-and-true application and repair methods. In this context, architects and engineers often relegate themselves to a minimal supervisory role during construction and planning. The writers have found several recurring instances of terrazzo cracking problems during construction as well as deterioration that could be prevented or minimized with attention to the responsibilities of all parties to communicate throughout the design process. Causes are often related to shrinkage of terrazzo, concentrated stresses attributable to configuration of divider strips, and impact loads. To objectively minimize deterioration rates of terrazzo, an experimental program was initiated to evaluate performance. Testing consisted of compressive strength and linear shrinkage tests on cementitious terrazzo under varying curing conditions and a durability test that applied a cyclic gravity wheel load to gaps at the edge of terrazzo tiles. The latter test used metal wheels and considered parameters of material type, gap size between terrazzo edge and adjacent steel plate, wheel diameter, vertical offset of tile, and vertical load being applied. Results indicated that proper curing of cementitious terrazzo is critical to achieving compressive strength and minimizing early shrinkage. For the durability test performed, epoxy terrazzo exhibited significantly less deterioration. Durability of terrazzo is affected primarily by gap size, upward vertical offset, and weight applied. Small wheel size and direction of loading can also contribute to deterioration. It is important that architects, engineers, and contractors understand methods that ensure material properties, minimize stress concentrations, and use appropriate divider strip spacing to minimize deterioration attributable to cracking and impact load. These steps will ensure the visual appearance and durability expected by the project team.