Methods of test for chemical resistant mortars, Part II: Sulphur type
1967 Edition

To prepare test samples, melt approximately 1 to 2.5 kilograms of sulphur mortar within an hour, maintaining the temperature between 130°C and 140°C for at least 15 minutes while stirring gently to lift aggregates and avoid air entrapment. Use moulds sized 25 mm x 25 mm x 250 mm lined with a plastic sheet featuring a rectangular opening and place a 25 mm diameter, 25 mm high plastic tube over this hole as a reservoir. Pour the molten mortar through the opening to fill the reservoir, compensating for shrinkage during cooling. Allow the specimens to solidify in the mould and cure them for 48 hours before removing and finishing by filing or grinding flush with the mould surface. Prepare a minimum of six specimens for testing following IS 4456 Part I clauses 6.4, 6.5, and 6.6.

Compressive strength determination involves casting molten sulphur mortar into moulds measuring 25 x 25 x 250 mm, aging the specimens within these moulds for 48 hours, and testing at least six specimens for accuracy. The test follows conditioning and loading protocols specified in IS 4456 Part I (1967) Clauses 6.4, 6.5, and 6.6, which include applying a steady load until failure and recording the maximum load. This standardized approach ensures consistent and reliable measurement of compressive strength.

Moisture absorption is measured by preparing mortar bars of size 25 x 25 x 250 mm and curing them for 48 hours. Specimens are dried to a constant weight (W1), then submerged in water at elevated temperature for a defined period, removed, surface dried, and weighed again to obtain W2. The moisture absorption percentage is calculated using the formula ((W2 - W1)/W1) × 100. At least six specimens are tested to ensure statistical reliability, with procedures aligned to IS 4456 Part I clauses 6.4, 6.5, and 6.6.

Sulphur content determination starts with melting approximately 2.5 kg of sulphur mortar at 130°C to 140°C for no less than 15 minutes with gentle stirring. The molten material is cast into moulds (25 x 25 x 250 mm) and cured for 48 hours. Chemical extraction is then performed following IS 4456 Part I methods, typically involving solvent extraction using carbon disulphide in a reflux apparatus. The sulphur content percentage is calculated by the weight loss of the filter paper after extraction divided by the specimen weight, multiplied by 100, ensuring precise quantification of sulphur in the mortar.

Chemical resistance is evaluated by immersing specimens aged 48 hours in moulds into aggressive chemical solutions as per IS 4456 Part I Clauses 6.4-6.6, monitoring for deterioration, weight loss, and strength reduction. Aggregate settlement is generally assessed visually by inspecting specimens post-curing for segregation or layering, with bond strength tests also providing indirect data on mortar integrity. Specimens typically measure 25 x 25 x 250 mm to maintain consistency across tests.