Quality Control

✓Written by Help The Engineer TeamReviewed by Er. Inderjit Sharma (Retd.), Punjab PWD What is soundness? It is the ability of aggregate to resist breaking down from weathering: repeated wetting and drying, heating and cooling, and freezing. Unsound stone slowly cracks and crumbles in the structure. How is it tested? The aggregate is soaked in

✓Written by Help The Engineer TeamReviewed by Er. Inderjit Sharma (Retd.), Punjab PWD What is Aggregate Impact Value (AIV)? It measures how well aggregate resists sudden blows, like the pounding from traffic wheels and rollers. A hammer is dropped on the stone 15 times and we weigh how much of it breaks into fine dust.

✓Written by Help The Engineer TeamReviewed by Er. Inderjit Sharma (Retd.), Punjab PWD What is specific gravity? It tells you how heavy the aggregate is compared with the same volume of water. A stone with specific gravity 2.65 is 2.65 times heavier than an equal volume of water. Water absorption tells you how much water

✓Written by Help The Engineer TeamReviewed by Er. Inderjit Sharma (Retd.), Punjab PWD What is this test? It finds the specific gravity and water absorption of fine aggregate and small coarse aggregate (below 10 mm), such as sand, stone dust and grit. Pieces this small can’t be weighed in a wire basket, so we use

✓Written by Help The Engineer TeamReviewed by Er. Inderjit Sharma (Retd.), Punjab PWD What is bulking of sand? When dry sand gets slightly damp, it swells in volume. A box of damp sand therefore holds less actual sand than a box of dry sand. Why it matters: if sand is measured by volume (boxes, head

✓Written by Help The Engineer TeamReviewed by Er. Inderjit Sharma (Retd.), Punjab PWD What is bulk density? It is the weight of aggregate that fills a container of known volume, including the air gaps between the pieces. It is expressed in kg/litre (or kg/m³). What are voids? The empty spaces between the aggregate pieces, as

✓Written by Help The Engineer TeamReviewed by Er. Inderjit Sharma (Retd.), Punjab PWD What is this test? It checks the shape of coarse aggregate. Good aggregate is roughly cubical. Pieces that are too thin (flaky) or too long (elongated) are weak and pack badly. Why it matters: flaky and elongated stones break under rollers and

✓Written by Help The Engineer TeamReviewed by Er. Inderjit Sharma (Retd.), Punjab PWD What is Free Swell Index (FSI)? It is the increase in volume of a soil when it is put in water, with nothing holding it down, expressed as a percentage. Why it matters: some clays, like black cotton soil, swell when wet

✓Written by Help The Engineer TeamReviewed by Er. Inderjit Sharma (Retd.), Punjab PWD What is this test? It finds the dry density of soil in the field, right where it has been compacted. You dig a small hole, weigh the soil you removed, and find the hole’s volume by filling it with sand of known