The IS 4139:1989 standard outlines the criteria for calcium silicate bricks utilized in construction, detailing their classification based on compressive strength, dimensional specifications, permissible tolerances, physical attributes, and drying shrinkage limits. It serves manufacturers, engineers, and quality control professionals involved in the production and specification of these bricks, including those incorporating fly ash. This standard guarantees that the bricks conform to stringent quality, strength, and durability requirements suitable for various construction purposes.
Overview
The IS 4139:1989 standard outlines the criteria for calcium silicate bricks utilized in construction, detailing their classification based on compressive strength, dimensional specifications, permissible tolerances, physical attributes, and drying shrinkage limits. It serves manufacturers, engineers, and quality control professionals involved in the production and specification of these bricks, including those incorporating fly ash. This standard guarantees that the bricks conform to stringent quality, strength, and durability requirements suitable for various construction purposes.
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Frequently Asked
Per IS 4139 (1989), calcium silicate bricks are categorized by their average compressive strength into four classes: Class 7.5 (7.5 to less than 10 N/mm²), Class 10 (10 to less than 15 N/mm²), Class 15 (15 to less than 20 N/mm²), and Class 20 (20 N/mm² and above). Individual bricks should not fall below 80% of the minimum strength of their class. Testing follows the procedures outlined in IS 3495 (Part 1): 1976. For averages, any value exceeding the upper class limit is capped at that limit to ensure consistent quality.
Yes, IS 4139 allows the inclusion of pulverized fuel ash (fly ash) in calcium silicate brick manufacturing, subject to limitations. The fly ash must comply with the specifications in IS 15648:2006 and be used in restricted quantities as specified in Clause 4.1. This supports sustainable practices by utilizing industrial by-products without compromising brick quality. For bricks made predominantly from fly ash and lime, IS 12894:2002 provides specific guidelines.
IS 4139 specifies two standard sizes for calcium silicate bricks: 190 mm × 90 mm × 90 mm and 190 mm × 90 mm × 40 mm. The dimensional tolerances allowed are ±3 mm for length and ±2 mm for both breadth and height. While other sizes may be produced by mutual agreement, the same tolerance limits apply to ensure uniformity and compatibility in construction.
Drying shrinkage is measured by first recording the wet length (L_w) of the brick specimen, then subjecting it to cycles of drying and cooling until length changes stabilize (less than 0.005 mm difference between measurements spaced at least 44 hours apart for drying plus 4 hours cooling). The dry length (L_d) is then measured. Shrinkage percentage is calculated using the formula: ((L_w - L_d) / L_w) × 100. The average shrinkage from three specimens represents the batch. While IS 4139 does not explicitly specify exact limits here, generally, drying shrinkage should be minimal (commonly below 0.1% to 0.2%) to prevent structural issues.
IS 4139 recommends adherence to IS 5454:1978 for sampling procedures and conformity evaluation of burnt clay bricks. Testing should follow IS 3495 (Parts 1-4):1976 standards. Drying ovens must have a minimum internal volume of 50 liters (approximately 8 liters per specimen), be airtight with adequate air circulation, maintain a temperature of 50 ± 1°C, and relative humidity around 17% using saturated calcium chloride solution. Test results should be rounded off according to IS 2:1960, aligning significant figures with specified values. These measures collectively ensure consistent quality and reliable conformity assessment.
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