This standard outlines a laboratory technique to evaluate the abrasion wear resistance of natural building stones. It employs a standardized abrasion testing apparatus featuring a rotating grinding disc to measure stone durability for use in high-traffic flooring and pavement applications. The specification is vital for professionals assessing stone suitability for construction projects involving heavy surface wear.
Overview
This standard outlines a laboratory technique to evaluate the abrasion wear resistance of natural building stones. It employs a standardized abrasion testing apparatus featuring a rotating grinding disc to measure stone durability for use in high-traffic flooring and pavement applications. The specification is vital for professionals assessing stone suitability for construction projects involving heavy surface wear.
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Contents
Structure
This section defines the criteria for the cast iron grinding paths used in the abrasion testing machines. The grinding path must be made from cast iron possessing a Shore's scaleroscope hardness in the range of 30 to 50. Hardness testing is required at a minimum of ten locations along the rim and multiple points on the grinding path, using a Shore's scaleroscope equipped with a diamond hammer. All numerical values are to be rounded following the rules in IS 2:1960, maintaining the significant figures as specified. The standard aligns with both international practices and local field necessities.
Test specimens are to be cubical with dimensions of 7.06 cm ±2%, resulting in each face having an area of 50 cm². Preparation involves saw cutting followed by finishing with grinding wheels to ensure all faces are parallel and true. The use of chisels and hammers is prohibited to prevent specimen damage. The grinding disc used is approximately 750 mm in diameter, rotating horizontally about a vertical axis. Thickness measurements before and after abrasion must be accurate to ±0.01 mm and rounded according to IS 2-1960.
The apparatus consists of a horizontal grinding disc approximately 750 mm in diameter, rotating around a vertical axis. The disc features a replaceable smooth grinding path. Specimens are secured in a square frame clamp equipped with a counter-weight to apply balanced pressure. The thickness of specimens is measured with an instrument capable of 0.01 mm accuracy. This setup ensures consistent abrasion testing as per the standard.
The specimen holding device is an open square frame fabricated from cast iron or steel. Its lower edge is positioned roughly 5 mm above the surface of the grinding disc. The specimen's center is located 220 mm from the disc's center. The frame holds the specimen loosely enough to permit free movement during abrasion. The grinding disc rotates at 30 ±1 revolutions per minute, and an automatic counter halts the process after every 22 revolutions. The loading lever is designed to be frictionless and parallel to the disc surface, with a self-aligning joint ensuring uniform pressure application.
Specimens are measured for thickness with a device accurate to 0.01 mm before testing. The abrasion disc rotates at 30 ±1 rpm, with an automatic counter stopping the disc every 22 revolutions to replenish abrasive powder. The grinding disc is approximately 750 mm in diameter and rotates about a vertical axis. Specimens are clamped in a square frame with a counter-weight applying the load. Test values are rounded as per IS 2-1960, maintaining the required significant digits.
The average loss of thickness (t) is calculated using the formula t = [10 × (W₁ - W₂) × V₁] / (W₁ × A), where W₁ is initial specimen weight, W₂ is final weight after abrasion, V₁ is initial volume, and A is surface area. Specimens are dried at 110°C for 24 hours and weighed with 0.1 g precision. Abrasion is performed using 20 g of emery abrasive powder per 22 revolutions under a 30 kg load at 30 rpm, with the specimen rotated 90° after 110 revolutions. All measurements are taken before and after abrasion, and average abrasion values from multiple specimens are reported. Final results are rounded in accordance with IS 2-1960.
This appendix provides details on the testing machine, including a horizontal grinding disc approximately 750 mm in diameter rotating about a vertical axis. The grinding path is replaceable and specimens are clamped in a square frame with counter-weight balance. Thickness measurement instruments must provide 0.01 mm accuracy. The specimen is abraded on the grinding path, with thickness recorded before and after testing.
Specimens are dried at 110°C for 24 hours and weighed to 0.1 g accuracy. The grinding disc is approximately 750 mm in diameter, rotating horizontally at 30 rpm. The specimen is loaded with 30 kg at its center. Emery abrasive powder of 20 g is evenly distributed on the grinding path before testing and replenished after every 22 revolutions. The total number of revolutions is 220, with the specimen rotated 90° after 110 revolutions. Specimens, abrasives, and the disc must be kept dry throughout the test. Thickness and weight are measured before and after abrasion.
All numerical values must be rounded according to IS 2-1960 standards, ensuring the number of significant digits in the rounded result matches those specified in the standard. The average thickness loss is calculated using the prescribed formula involving initial and final weights, volume, and surface area. Rounded results are used for compliance checks.
Frequently Asked
Per IS 1706 (Clause 2.1), specimens should be cubic with a dimension of 7.06 cm ±2%, each face having an area of 50 cm². Specimens are to be prepared by saw cutting followed by grinding wheels to ensure faces are true and parallel, while avoiding chisels and hammers to prevent damage. At least two specimens should be tested to ensure uniformity and reliable results.
IS 1706 defines a laboratory method where stone samples are subjected to controlled abrasive action using a rotating grinding disc with abrasive powder. The loss of weight or thickness after abrasion quantifies the wear resistance. This method simulates real-world wear conditions and helps classify stones for use in areas subjected to heavy foot or vehicular traffic.
The grinding disc is approximately 750 mm in diameter with a 200 mm wide annular grinding path made of cast iron having a Shore's scaleroscope hardness between 30 and 50. The abrasive powder is emery grain, 20 grams applied evenly before testing and after every 22 revolutions. The disc rotates at 30 rpm with a 30 kg load applied to the specimen during testing.
The specimen is held in a square clamp with the wearing surface upwards. A 30 kg load is applied at the specimen center pressing it against a horizontal rotating grinding disc (750 mm diameter) running at 30 rpm. Abrasive powder of 20 g is spread on the grinding path and replenished every 22 revolutions, with the specimen rotated 90° after 110 revolutions, maintaining dry conditions throughout.
Test results are averaged from multiple specimens as per Clause 6.1. Measurements use instruments accurate to 0.01 mm for thickness changes. Final values are rounded following IS 2-1960 rules, maintaining the significant digits specified in the standard. This ensures reproducible and reliable reporting of abrasion resistance.
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