Binding waste materials

Abstract

A study on the compressive strength achieved by precast cubic blocks, consisting of inert excavated waste material as the aggregate, Maltese Blue Clay together with xanx (Globigerina Limestone dust) and calcium lignosulfonate as binder, and additive respectively, has been carried out. Research was based on an understanding of the material and geotechnical properties of the binder constituent, which understanding was then applied to the design of the mixes. Analysis of the results was based on the compressive strength achieved by precast concrete blocks, in comparison to loading situations typical of the local construction industry, as well as comparison to results obtained from similar studies abroad. The testing approach used in this study was significantly different to that adopted in a concrete mix, in that the critical parameters that control strength were found to be those resulting from the strength properties of the clay binder, which properties depend on the degree of compaction achieved before subjecting the samples to unconfined compression. In view of this, the mechanisms of the compaction process were studied by carrying out tests in the oedometer, such that the time required for completion of the consolidation process could be estimated. This is considered to be an important consideration when determining the feasibility of the manufacturing process of these types of building units. For the blocks constructed in the laboratory, the time required for full consolidation was not possible to reach, and the compressive strengths reached were below building standards.