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refractory testing and development laboratory, was requested to develop an acid-resistant concrete for flooring and bund areas that was user-friendly and suitable for installation under typical South African site conditions. The refractory industry in South Africa has a long history of involvement in acid-resistant materials. Acid-resistant bricks were made in South Africa for many years by Vereeniging Refractories until the closure of the plant in 2016. Figure 1 shows a cut section of a semivitrified red acid brick with a typical black core. All alumina-silicate bricks have good resistance to acid attack and the choice of red, fawn, white acid, or even andalusite bricks was frequently based on price versus the available size tolerances of each grade. Potassium silicate lining materials have been commercially available overseas for many years and are recognized for their excellent resistance to all acids except hydrofluoric acid (Corrosionengineering.com, 2006). Typically, such potassium silicate materials were based on a siliceous aggregate and sodium fluosilicate as a setting agent. The potassium silicate was supplied in large drums for addition on-site. The standard crushing strength of such concretes was 14 MPa after 1 day and 24–28 MPa after the final cure was reached after 7 days. One special note pertains to many of these products. Once it has set and will be exposed to water before it is exposed to acid, the surface needs to be pre-treated with an acid mixture of 1 part commercial strength (33%) hydrochloric acid to 2 parts water. For applications in South Africa it would be an advantage to find a formulation that would be stable to water without the need for acid pretreatment. Although the use of fluosilicate and a condensed aluminium phosphate is prohibited as the setting agent in some European specifications, it is used locally. Only one sample of such a concrete was found for testing and hence the results may not be typical of such products. Crushing strength after 1 day was 6–14 MPa, and 11–25 MPa after 28 days. Potassium silicate concretes in sulphuric acid environments at ambient and low temperature in South Africa