This standard outlines the procedure for assessing the stability and expansion characteristics of building limes through the Le-Chatelier test. It details the necessary sample preparation, apparatus setup, and step-by-step testing to evaluate lime durability. The specification is vital for professionals ensuring the quality and compliance of lime used in construction projects.
Overview
This standard outlines the procedure for assessing the stability and expansion characteristics of building limes through the Le-Chatelier test. It details the necessary sample preparation, apparatus setup, and step-by-step testing to evaluate lime durability. The specification is vital for professionals ensuring the quality and compliance of lime used in construction projects.
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Frequently Asked
To prepare the lime sample for testing, combine hydrated lime with one-third of its mass in ordinary Portland cement (as per IS 269:1989) and four times its mass in standard sand (according to IS 650:1991). Thoroughly dry mix these components, then add water amounting to 12% of the total dry mix by weight. Mix thoroughly to form a homogeneous mortar and proceed immediately with the test.
The test requires three Le-Chatelier moulds conforming to IS 5514 - 1969, each internally greased and placed on a non-porous base plate. Additionally, non-porous cover plates and small weights are used to cover the moulds. A damp air cupboard is needed for curing, and a steam boiler providing saturated steam at atmospheric pressure is required for the steaming phase. These components together facilitate accurate measurement of lime expansion.
Expansion is assessed by casting mortar specimens prepared with hydrated lime, Portland cement, and standard sand, then curing them. Measurements of linear expansion are made before and after exposure to saturated steam using the Le-Chatelier apparatus. The calculated net expansion reflects the lime's stability; values exceeding specified limits indicate unsound lime prone to cracking or disintegration.
The standard allows a maximum net expansion of 10 mm after subtracting 1 mm to account for cement-related expansion. This net expansion is measured after subjecting the specimen to saturated steam for 3 hours following initial curing. Exceeding this threshold indicates the lime is unsound and unsuitable for construction use.
The test replicates real-life conditions by preparing a mix of hydrated lime combined with Portland cement and standard sand in proportions reflecting typical mortar compositions. The addition of water and subsequent curing simulate the moisture and chemical interactions that occur in masonry. Subjecting the samples to damp air and steam curing mimics environmental exposure, allowing for accurate evaluation of the lime's volume stability and durability.
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