Construction Materials: Properties, Testing and Storage
This domain tests cement types and tests, aggregate limits, concrete grades and testing, brick classes, steel grades, and correct storage practice.
Cement
OPC 33/43/53 (IS 269, IS 8112, IS 12269); PPC (IS 1489). Initial setting time not less than 30 minutes, final not more than 600 minutes, found with the Vicat apparatus. Soundness by Le Chatelier; fineness by Blaine or sieve. Store on a dry raised platform, about 8–10 bags high, clear of walls, first-in-first-out, and use within about three months.
Aggregates and concrete
Fine aggregate per IS 383; fineness modulus roughly 2.2–3.2 for concrete sand; silt content limited (about 3% for uncrushed sand). Coarse aggregate in 20 mm and 10 mm sizes. IS 456 governs grades and water-cement ratio. M20 means 20 N/mm² at 28 days on 150 mm cubes, three specimens. Workability by slump test (IS 1199).
Bricks and steel
Burnt clay bricks (IS 1077) are classed by compressive strength from 35 down to 5; higher classes have water absorption not exceeding 20%; efflorescence should be nil to slight. Reinforcement: Fe415, Fe500, Fe500D per IS 1786.
Mortar
Cement:sand by volume, typically 1:4 to 1:6; mix dry, add water, and use within about 30 minutes of mixing.
Worked example
A cement bag on site is lumpy and the batch date is five months old. Reasoning: lumps show moisture set, and storage beyond three months needs retesting. The correct decision is to reject it for structural concrete; it may be used only for non-structural work after testing and approval.
Traps
Confusing initial with final setting time; treating 7-day strength as acceptance; volume batching where weigh batching is specified; storing cement directly on the floor.