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This study shows the results of the investigation of the strength performance, and residual strength of a single component inorganic binder system Cast Clean S27®. The study was conducted using three different foundry sand sources in South Africa. Sample A is an alluvial coastal sample, sample B is an alluvial riverbed sample and Sample C is a blasted sample from a consolidated quartzite rock. The binder was also cured using three different curing mechanisms. The aim of the investigation was to determine the variation of strength performance and residual strength between the different South African sand sources based upon the physical and chemical properties of the sand sources. The moulding sand was prepared using three possible curing mechanisms which are carbon dioxide curing, ester curing and heat curing. The strength measurements were determined by bending strength. Sample A and sample C sand had good strength development. Sample B sand had inferior strength development and excellent high temperature residual strength. The study showed that the single component inorganic binders have good strength development and low residual strength. The silica sand properties have major contributing factors on both strength development and residual strength. The degree of influence of silica sand properties on strength performance and residual strength is dependent on the time of curing and method of curing.

There is a need to introduce modern sand binder systems in the South African foundry industry as a means of improving its competiveness through the reduction of scrap castings and compliance to environmental regulations. According to the Industrial Policy Action Plan (IPAP). The foundry industry will play an important role with regards to the economic infrastructure priority advocated in the National Development Plan (NDP) of South Africa. In this study, a new generation water glass binder is introduced in a local foundry for production of cores for export plumbing casting production. The new water glass introduced is unique in that it contains an inorganic breakdown agent. The core making operating parameters including binder content, temperature and cycle time are optimised through core making trials without any alterations on the coremaking machines. Production data was evaluated using an optimization feature of Microsoft excel software. The results provided a set of optimum operating variables to manufacture 80-100% good quality sand cores for casting applications with an environmentally friendly binder. The most favourable binder content is above 2.60%.The most favourable operating temperature range is 160-174 0C. Therefore temperature and related energy costs can be reduced. The shortfall is reduction in cycle time.

Bentonite is the most widely used foundry binder. Most of the iron castings are made in greensand systems which make use of bentonite as a binder. The bentonite used in greensand moulding is usually activated with sodium carbonate to achieve desirable properties. Activation of bentonite is known to improve mould related properties like giving a high wet tensile strength and improving the durability. The practice of activation is more common with calcium bentonite. A number of bentonite deposits tend to remain unbeneficiated due to their low cation exchange capacity (CEC) which are regarded as low quality commercial grade. The primary characteristic that shows the increased activation is the swelling index of the bentonite. This study investigated the influence of rehydration and activation in improving the quality of low commercial grade sodium bentonite. The bentonite samples were activated with sodium carbonate. Rehydration and activation was seen to improve the CEC and swelling index. The increase in CEC and swelling index was however not consistent with the gains in sodium.