The specification defines the criteria for moulds employed in casting cement and concrete test specimens such as cubes, cylinders, beams, and bars for strength evaluation. It outlines the appropriate materials, dimensional requirements, permissible tolerances, and marking protocols to guarantee precise and consistent results in compressive and flexural strength assessments. This document is crucial for producers and users of testing moulds within laboratories and construction quality assurance.
Overview
The specification defines the criteria for moulds employed in casting cement and concrete test specimens such as cubes, cylinders, beams, and bars for strength evaluation. It outlines the appropriate materials, dimensional requirements, permissible tolerances, and marking protocols to guarantee precise and consistent results in compressive and flexural strength assessments. This document is crucial for producers and users of testing moulds within laboratories and construction quality assurance.
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Frequently Asked
As per IS 10086 Clause 3.1 and Table 1, moulds must be made from materials that do not absorb water, are chemically inert with respect to concrete, and maintain dimensional stability during use. Common materials include cast iron and mild steel for cube and beam moulds, while cylindrical moulds can be made from cast iron or mild steel. Bar moulds often use mild steel or stainless steel. Plastic may be used for lightweight applications, but wood is generally avoided unless properly sealed. Steel is favored for its durability and precision.
IS 10086:1982 prescribes precise dimensional limits to ensure accuracy in testing. Cube moulds have face distances with tolerances ranging from ±0.1 mm for 50 mm size to ±0.4 mm for 300 mm size cubes. Heights match the face dimensions within the same tolerances. Wall thickness varies between 6 mm to 10 mm depending on size, and the angle between faces is maintained at 90° ± 0.5°. Cylindrical moulds have a mean internal diameter of 150 ± 0.2 mm and actual diameter tolerance of ± 0.5 mm, with height specified as 300 ± 1 mm. Planeness tolerances are also defined, such as 0.03 mm for new cube mould faces and 0.05 mm for those in use.
Mould parts must be assembled so that they are firmly and rigidly held during the entire procedure of filling, handling, and vibration to prevent distortion. The base plates are usually fixed using cleats that can be spring-loaded or fastened with threaded studs and nuts or wing nuts. Additionally, lock nuts or locating pins may be employed to ensure the assembly remains stable and positive during use. This rigid fastening helps maintain dimensional accuracy and integrity of the test specimens.
The internal surfaces of moulds should be smooth and machined to exact dimensions. Surface defects such as blowholes or honeycombing are permitted within controlled limits, provided they are repaired by welding or the insertion of mild steel pins and then finished flush by machining or filing. The maximum allowed blowholes are up to 5 for cube moulds of sizes 150 mm or smaller and up to 10 for larger cube moulds, cylindrical moulds, and beam moulds. The maximum diameter of blowholes for cube and beam moulds is 5 mm with a depth of 3 to 5 mm, while cylindrical moulds allow larger defects up to 20-25 mm.
Yes, according to Clause 7.1 of IS 10086, every mould component must be clearly and permanently marked with the manufacturer's name or registered trademark and the date of manufacture. These markings must be applied in such a way that they do not interfere with the mould's function or affect test specimen formation. This marking system facilitates traceability and quality control throughout the mould's service life.
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