This standard outlines comprehensive guidelines for the dimensions and finishing of natural stones used in masonry structures. It covers prescribed sizes, allowable dimensional variations, and dressing practices for different masonry types including ashlar, rubble, and curved elements like arches and domes. The code is intended to assist engineers, architects, and construction professionals in achieving consistent quality and durability in stone masonry.
Overview
This standard outlines comprehensive guidelines for the dimensions and finishing of natural stones used in masonry structures. It covers prescribed sizes, allowable dimensional variations, and dressing practices for different masonry types including ashlar, rubble, and curved elements like arches and domes. The code is intended to assist engineers, architects, and construction professionals in achieving consistent quality and durability in stone masonry.
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Frequently Asked
Based on IS 1127, the typical recommended dimensions for ashlar masonry stones include lengths of 597 mm, 697 mm, and 797 mm; breadths of 297 mm, 347 mm, and 397 mm; and heights of 297 mm, 347 mm, and 397 mm. Mortar joints are advised to be 3 mm thick to enable precise fitting. Tolerances allowed are ±5 mm on length and breadth, and ±3 mm on height, ensuring uniformity and high-quality workmanship.
IS 1127 specifies that for ashlar masonry stones, length and breadth tolerances are ±5 mm, and height tolerance is ±3 mm. For other masonry types like rubble and block-in-course, the length and breadth can vary between +5 mm and -10 mm, while the height tolerance is ±5 mm. These tolerances accommodate the varying precision requirements for different masonry work, maintaining structural soundness.
Stones intended for arches, domes, or circular molded masonry must be dressed similarly to ashlar sunk or molded stones, with joint surfaces precisely cut to be radial relative to the center of curvature. This radial dressing ensures tight joints and proper load distribution along the curve. Additionally, stones from stratified rocks should be laid respecting the plane of stratification to maintain strength and durability.
According to IS 1127, stones must be accurately cut and dressed with chiseled beds and joints free from bush hammering. Surface deviations should not exceed 3 mm under a straight edge, and exposed faces must be finely tooled within 6 mm from the surface. Edges and corners, especially quoins, should be true, square, and perpendicular. For stratified stones, orientation along the stratification planes is essential to maintain durability.
Yes, IS 1127 mandates that stones from stratified rock formations be quarried and dressed so that when placed in masonry, their planes of stratification are parallel to the bed joints. This orientation minimizes the risk of splitting and enhances the stone’s mechanical performance and longevity within the structure.
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