The 1992 edition of IS 2248 offers an extensive glossary of terminology associated with clay-based building materials such as bricks, blocks, and tiles. It standardizes definitions concerning production methods, product varieties, surface textures, and common imperfections, ensuring effective communication among professionals engaged in manufacturing, specifying, and utilizing clay construction materials in India.
Overview
The 1992 edition of IS 2248 offers an extensive glossary of terminology associated with clay-based building materials such as bricks, blocks, and tiles. It standardizes definitions concerning production methods, product varieties, surface textures, and common imperfections, ensuring effective communication among professionals engaged in manufacturing, specifying, and utilizing clay construction materials in India.
Audience
Contents
Structure
This section outlines the range of terms associated with clay-based building materials including bricks, blocks, and tiles. It defines 'webs' as the internal partitions within blocks or tiles that separate cells. The standard emphasizes quality assurance through BIS certification and periodic updates to maintain relevance. It ensures consistent comprehension of terminology across the clay product manufacturing and usage sectors.
IS 2248 provides a standardized glossary covering terms related to clay building units. Key definitions include raw materials like natural clay and shale, clay products such as bricks and tiles, and processes like firing that impart strength. It differentiates properties such as water absorption and compressive strength essential for material classification. For detailed technical specifications, refer to IS 1077 and IS 1725.
While IS 2248 focuses on terminology, it highlights raw materials comprising mainly clay, shale, and occasionally sand or additives. Important factors include plasticity, particle size distribution, moisture content, and mineral make-up, all influencing product quality. Typical compositions range from 40-60% clay and 20-40% sand, with moisture adjusted to 15-25% for moulding. Tests such as plasticity index and shrinkage assessment confirm suitability.
This part discusses the primary shaping methods for burnt clay bricks, including hand moulding where clay is manually pressed into wooden moulds and table moulding which enhances uniformity by moulding on tables before drying. The term 'webs' is defined here as internal partitions ensuring structural integrity. Compliance with IS 2248 is verified through BIS Standard Mark certification, confirming adherence to quality controls.
The standard classifies surface textures of clay bricks and tiles into exposed (smooth and intended for visible surfaces), roughened (mechanically textured to improve mortar adhesion), and sand finishes (surfaces coated with sand for enhanced bonding and slip resistance). These finishes influence both aesthetics and functional performance such as plaster keying and durability.
Bricks are defined with maximum dimensions of 300 mm length, 150 mm width, and 100 mm height. Common bricks have a frog volume not exceeding 20% to balance weight reduction and strength. Heavy-duty bricks intended for demanding applications feature higher compressive strength and lower water absorption. The frog—a shallow cavity on a brick face—facilitates mortar bonding and reduces material volume.
Clay tiles, thinner than bricks, serve purposes such as flooring, roofing, ceilings, and wall coverings. Flooring tiles are produced by pressing or extrusion, terracing tiles provide flat surfaces for floors or roofs, and ceiling tiles are typically used beneath interlocking roofing tiles. Proper installation on a prepared base ensures durability and performance.
Blocks are divided into hollow and solid types. Hollow blocks contain voids exceeding 25% of the total volume, with holes oriented either parallel or perpendicular to the bearing surface. Solid blocks are fully compact without internal cavities. 'Cells' refer to these hollow spaces enclosed by the block’s outer shell, contributing to reduced weight and improved insulation.
This section defines physical properties such as compressive strength, water absorption, and dimensional tolerances, along with typical surface finishes. It also identifies common defects including cracks, chips, warping, efflorescence, lumps, and firing irregularities like underburnt or overburnt conditions. Bulk density calculations and web thickness recommendations support quality assessment.
Key structural parameters include standard modular brick sizes with a ±3 mm tolerance and minimum compressive strengths varying according to usage classifications. Water absorption limits and efflorescence grading ensure material reliability. The standard includes formulas for calculating compressive strength and provides typical classifications for brick grades used in different construction scenarios.
Frequently Asked
IS 2248 categorizes clay building materials primarily into bricks, blocks, and tiles. Bricks are fired clay units used in masonry; blocks are larger clay units utilized for walls and partitions; tiles are thinner units designed for roofing, flooring, or walls. Additionally, other clay products such as pavers, pipes, and decorative elements are encompassed. The standard focuses on establishing clear terminology concerning material composition, sizing, and functional application to ensure uniform understanding.
The standard outlines various surface finish types for clay bricks and tiles, including common (natural fired surface), ground (smoothed by grinding), glazed (coated with a glassy layer for appearance and water resistance), pressed (formed by mould pressing for texture uniformity), and sand-faced (sprinkled with sand before firing to add texture). These classifications influence the visual appeal, water absorption characteristics, and mortar adhesion properties of the products.
IS 2248 details manufacturing techniques such as hand moulding, where clay is manually shaped using wooden or metal moulds, and machine moulding, which involves mechanical shaping through devices like hand-screw presses, soft-mud moulding machines, extruders, and dry or semi-dry presses. These methods apply to the production of bricks, blocks, and tiles, ensuring standardized terminology and facilitating quality control in clay product fabrication.
Common defects identified by IS 2248 include cracks caused by drying or firing stresses, blisters formed from trapped gases during firing, warping or distortion of units, efflorescence representing surface salt deposits, lumps of unburnt clay within bricks, overburnt bricks which are brittle and darkened due to excessive firing, underburnt bricks that are weak and soft, and pinholes resulting from gas escape during firing. These defect terms aid in quality assessment and corrective manufacturing practices.
Drying shrinkage is defined as the percentage reduction in length or volume of clay units due to moisture loss during drying, calculated by comparing wet and dry dimensions. Fired shrinkage refers to the dimensional decrease occurring when dry clay units are heated to the maturing temperature during firing, where the clay attains optimal strength. Both properties are critical for assessing dimensional stability and ensuring product quality.
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