This specification outlines the criteria for preformed expansion joint fillers composed of cashewnut shell liquid (CNSL) aldehyde resin combined with coconut pith, intended for use in concrete pavements, runways, bridges, and similar structures. It details the material constituents, production methods, physical characteristics, testing protocols, and packaging requirements to ensure the fillers perform reliably as non-extruding, resilient components under compression and environmental exposure.
Overview
This specification outlines the criteria for preformed expansion joint fillers composed of cashewnut shell liquid (CNSL) aldehyde resin combined with coconut pith, intended for use in concrete pavements, runways, bridges, and similar structures. It details the material constituents, production methods, physical characteristics, testing protocols, and packaging requirements to ensure the fillers perform reliably as non-extruding, resilient components under compression and environmental exposure.
Audience
Contents
Structure
Overview of the standard's coverage including the use of hot-applied sealing compounds in joints of concrete pavements and structural elements, specifying dimensional and performance criteria for expansion joint fillers.
Details on the compression testing requirements, sample preparation as per IS 10566-1983, and criteria for physical and dimensional evaluations to assure material compliance.
Guidelines on polymerizing CNSL, mixing with fillers and hardeners, moulding, pressing to specified density, and curing procedures to produce resilient filler slabs.
Essential mechanical properties including compression strength, recovery percentage, mass loss limits, extrusion restrictions, and durability under handling stresses.
Specifications on filler size conformity to contract requirements and acceptable deviations in thickness, depth, and length to maintain joint integrity.
Instructions for labelling packages with manufacturer identification, product size, and optional BIS certification marks to ensure traceability and compliance.
Protocols for random sampling, sample size requirements, and detailed testing procedures to verify compliance with mechanical and dimensional standards.
Information on licensing and regulations governing the use of the BIS Standard Mark as evidence of conformity with the Indian Standard.
Recommendations for proper use of fillers including compression test limits, rounding rules for measurements, and compatibility with related chemical materials.
List of associated Indian Standards and chemical specifications referenced within the document, along with rounding off examples and test method summaries.
Frequently Asked
The fillers utilize cashewnut shell liquid (CNSL) polymerized with phosphoric acid, combined with coconut pith serving as filler material. Additionally, calcium hydroxide is included for stability, while paraformaldehyde and furfuraldehyde act as hardening agents. Rubber latex is added to enhance flexibility and reduce crumbling, and optionally, baby fibre may replace part of the filler to improve flexural strength.
Initially, CNSL undergoes polymerization through heating with acid. The polymerized resin is blended with coconut pith, calcium hydroxide, paraformaldehyde, and furfuraldehyde. This mixture is then pressed into wooden molds achieving a density around 450 g/cm³, forming slabs approximately 12 mm thick. These slabs are cured either naturally or in a warm chamber to develop required mechanical strength. Additives like rubber latex and baby fibre may be incorporated to enhance durability and flexibility.
Key physical parameters include a recovery of at least 70% of the original thickness after compression, a compressive load ranging from 0.7 to 5.3 N/mm² to reduce thickness by half, and a mass loss not exceeding 5% post-compression. Extrusion of the filler edge under compression must not surpass 6.5 mm, and the material should resist deformation or damage during handling, ensuring resilience and durability.
Fillers must conform to the dimensions stipulated in the contract or purchase order. Permissible dimensional variations include a maximum thickness tolerance of +2.5 mm, depth tolerance of +5 mm, and length tolerance of ±7.5 mm. These tolerances ensure proper installation and functional performance within expansion joints.
Testing involves verifying dimensional conformity to contract specifications, assessing resilience through compression and recovery tests, and confirming non-extrusion under load. Additional evaluations include measurements of density, hardness, water absorption, and durability against temperature and moisture exposure. Standard test methods like ASTM D3575 and ASTM D570 or their equivalents are typically employed to ensure the product meets IS 1838 Part 2 requirements.
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