sandstone (slabs and tiles)
1977 Edition

The standard defines the dimensional ranges for sandstone slabs and tiles as follows: Lengths range from 15 cm to 360 cm in 5 cm increments; widths vary from 15 cm to 90 cm also in 5 cm steps; thickness spans from 15 mm to 100 mm in 5 mm increments. Any measurements falling between these increments are rounded down to the nearest lower size, establishing the tolerance limits for length and breadth. This sizing framework ensures uniformity for applications such as flooring, roofing, and cladding.

To confirm the quality of sandstone slabs, the following tests are mandated: Water absorption must not exceed 2.5% by mass (tested per IS 1124:1974); transverse (flexural) strength should be at least 7 N/mm² (IS 1121 Part II:1974); abrasion resistance requires an average wear of no more than 2 mm and a maximum of 2.5 mm per specimen (IS 1706:1972); and durability tests ensure there is no spalling, cracking, or disintegration (IS 1126:1974). These assessments collectively ensure slabs are fit for flooring, roofing, and facade use.

Sampling is performed by randomly selecting slabs or tiles from each production lot using random number tables as per IS 4905:1968. Sample sizes depend on the lot quantity: up to 100 units require 5 samples with zero allowable defects, 101-300 units require 8 samples with zero defects allowed, 301-500 units require 13 samples with zero defects, and 501-1000 units require 20 samples with one defect permissible. After initial general and dimensional inspections, a sub-sample undergoes physical testing (transverse strength, water absorption, durability, abrasion). The lot is accepted only if no failures occur in the sub-sample tests.

Defect limits are defined based on lot size and sampling tables. Any slab or tile that fails either general criteria (dimensions, appearance) or physical property requirements is considered defective. Acceptance depends on whether the number of defective units is within the permissible threshold specified for the lot size—for example, zero defectives allowed in smaller lots and up to one defective permitted in larger lots (501 to 1000 units). Common defects include dimensional inaccuracies, excessive water absorption, inadequate strength, wear beyond limits, and surface flaws like cracks or spalling. These criteria ensure quality adherence for use in flooring, roofing, and facade works.

Durability and wear resistance are ensured through strict limits on physical properties: water absorption is restricted to a maximum of 2.5% by weight, transverse strength must be at least 7 N/mm², and abrasion resistance requires an average wear not exceeding 2 mm with a maximum of 2.5 mm per specimen. Additionally, durability tests confirm the slabs do not exhibit spalling, cracking, or disintegration after exposure to prescribed conditions. These specifications guarantee that sandstone slabs and tiles withstand service conditions effectively for flooring, roofing, and wall cladding applications.