soil-based blocks used in general building construction
1982 Edition

While IS 1725 (1982) primarily focuses on material properties and testing methods, common practice for soil-based blocks generally aligns with modular dimensions such as 230 x 115 x 75 mm, 230 x 110 x 70 mm, and larger sizes like 300 x 150 x 100 mm depending on structural requirements. These sizes ensure uniformity and ease of construction, although specific regional or manufacturing variations may exist. For precise dimensional standards, IS 2185 (Part 1) or local building codes should be consulted.

According to the standard, soil-cement blocks are classified mainly as Class 20 and Class 30 based on compressive strength. Class 20 blocks require a minimum average compressive strength of 20 kgf/cm², while Class 30 blocks must achieve at least 30 kgf/cm². Furthermore, individual blocks should not have strength less than 80% of their class minimum to ensure consistency. Testing should comply with IS 3495 (Part I) - 1976 procedures to maintain structural reliability.

Weather resistance testing simulates natural rainfall by applying water droplets ranging from 2 mm (medium intensity) to 4 mm (high intensity) diameter, with a terminal velocity capped at 6.5 m/s and rainfall intensity between 15 to 30 mm/hr. Three selected blocks are exposed to a water spray for two hours with water directed at one face from 18 cm distance. The blocks pass if the maximum pit diameter on the surface is no greater than 1 cm and the weight loss after testing does not exceed 5%, demonstrating adequate durability against weathering.

The standard does not explicitly mandate marking requirements for soil-based blocks. However, common industry practice encourages manufacturers to imprint identification marks such as the manufacturer’s name or logo, block classification, batch number, and strength grade on blocks to ensure traceability and quality control. For detailed marking guidelines, references like IS 2185 for concrete blocks or general masonry standards may be applicable.

Sampling is conducted following IS 5454-1978 guidelines, where 20 blocks are randomly selected from a production lot after removing surface imperfections. These blocks are arranged in contact on a flat surface, and their overall dimensions are measured either in a continuous row or in segments of 10 blocks with dimensions aggregated. Dimensional limits for length, breadth, and height are specified for each block size. From these, three whole blocks are chosen for further detailed testing such as weathering resistance and compressive strength to confirm compliance with the standard.