This standard defines the chemical testing procedures for determining the composition of asbestos fibres used in asbestos cement products. It outlines precise methods to measure major chemical components including silica, iron oxides, aluminium oxide, calcium oxide, magnesium oxide, sodium oxide, and carbon dioxide, ensuring reliable quality control and compliance.
Overview
This standard defines the chemical testing procedures for determining the composition of asbestos fibres used in asbestos cement products. It outlines precise methods to measure major chemical components including silica, iron oxides, aluminium oxide, calcium oxide, magnesium oxide, sodium oxide, and carbon dioxide, ensuring reliable quality control and compliance.
Audience
Contents
Structure
Frequently Asked
IS 5328 details the testing procedures for identifying the chemical makeup of asbestos fibres utilized in asbestos cement manufacturing. It mainly focuses on assessing key oxides such as silicon dioxide, magnesium oxide, calcium oxide, ferric oxide, aluminium oxide, sodium oxide, potassium oxide, and moisture content through loss on ignition. The purpose is to verify the fibre's suitability and consistency for production, aligning with IS 2-1960 rounding standards and related codes like IS 3632 and IS 4844.
Silica content is measured gravimetrically by first fusing the sample with sodium carbonate to produce soluble sodium salts, followed by acid treatment with hydrochloric acid to dissolve the melt and precipitate silica. The precipitate is filtered, ignited, and weighed. Repeated treatments with hydrofluoric acid and sulfuric acid remove impurities such as ferric oxide and alumina, which are subtracted from the impure silica weight. This gravimetric technique ensures precise quantification by eliminating interfering oxides.
The determination of carbon dioxide uses a Knorr alkalimeter setup comprising several components: a gas washing bottle with concentrated sulfuric acid for moisture control; drying tubes filled with soda-asbestos (ascarite), copper sulfate, and drying agents to remove moisture and gases; the Knorr alkalimeter unit with a dropping funnel, distillation flask, and condenser; absorption tubes for capturing carbon dioxide; a trap to prevent backflow; and a valve or pinched tubing to regulate airflow. This configuration facilitates accurate absorption and measurement of CO2 released from the sample.
For sodium oxide determination, IS 5328 specifies the use of sodium carbonate to fuse silicate samples, converting sodium into soluble salts. Concentrated hydrochloric acid (sp. gr. 1.16) is used to moisten the sample powder and convert basic salts and oxides to chlorides. The key reagent sodium zinc uranyl acetate solution is employed to precipitate sodium as sodium zinc uranyl acetate hexahydrate for gravimetric analysis. The reagent preparation follows the prescribed method in the standard, ensuring selective precipitation and accurate measurement.
Sample preparation involves quartering the laboratory specimen down to approximately 25 grams, then dividing into ten equal portions, halving each, and mixing repeatedly until about 3 grams remain. This 3 g sample is spread thinly over a 20 x 20 cm surface to ensure uniformity. Five bundles of long asbestos fibres, each around 0.5 grams and free from contaminants, are extracted, combined, and dried at 110°C until constant weight is achieved, with the final test specimen weighing 0.5 ± 0.02 grams. Subsequent chemical treatments involve acid digestion with dilute sulfuric acid and hydrofluoric acid, followed by fusion with sodium carbonate, and successive precipitation and oxidation steps to isolate various oxides accurately.
Ask AI about any clause, requirement, or provision in IS 5328. Get instant, clause-cited responses powered by our indexed library.
Free tier includes 150 queries (50 AI + 100 Reference) · No credit card required