Quality Checks Every Site Should Do

Concrete: slump, cubes and mix control

Concrete is the item most worth checking, because once it has set, a bad batch cannot be undone. Two everyday tests matter.

The slump test checks workability — how wet or stiff the fresh concrete is — before it goes into the shuttering. Too dry and it will not compact around the reinforcement; too wet (often because someone added extra water to make pouring easier) and it loses strength badly. The slump is measured on site with a slump cone against the value specified for that mix.

Cube testing checks strength. Sample cubes (typically 150mm) are cast from the actual concrete being poured, cured in water, and crushed in a lab — commonly at 7 days (an early indicator) and 28 days (the acceptance age at which the concrete should reach its design strength, such as M25 meaning 25 N/mm²). Indian Standard (IS) codes specify how many samples to take per volume of concrete poured, how to cure and test them, and the criteria for accepting the results.

Also watch the basics: correct mix grade for each element, proper compaction with a vibrator (no honeycombing), and clean, well-oiled shuttering that does not leak the cement slurry.

Steel and curing — the two most common failure points

Steel (reinforcement) checks start at delivery: verify the grade (commonly Fe500 / Fe500D), the diameter of each bar, and that it carries proper mill markings; reject rusted, pitted or bent stock. On site, before any concrete is poured, someone must check the bar-bending schedule against what is actually tied — number of bars, spacing of stirrups, laps at the right places, and above all the cover (the gap between steel and the outer concrete face, held with cover blocks). Too little cover is one of the biggest causes of early corrosion and cracking in Indian buildings, especially in humid and coastal areas.

Curing is the single most neglected quality step. After concrete sets it must be kept continuously moist — by ponding, wet gunny bags, or sprinkling — for a sustained period (IS codes specify minimum curing durations depending on cement type). Concrete that dries out too early can lose a large share of its potential strength and develops surface cracks, no matter how good the mix was. On a tight schedule, curing is the first thing site teams cut. Owners should physically check that slabs and columns are being kept wet, not just assume it is happening.

Common failures, IS codes and supervision

Most quality failures on Indian sites are not exotic — they are the predictable result of skipping the checks above. The usual suspects: adding extra water to concrete for easier pouring, insufficient or no curing, inadequate cover leading to rusting steel, honeycombing from poor compaction, using the wrong mix grade, plaster cracking from unsound sand or rushed work, and waterproofing done carelessly at junctions and sunk slabs.

Indian Standard (IS) codes exist precisely to prevent these — there are codes covering plain and reinforced concrete practice, concrete mix proportioning, methods of testing concrete and its materials, and detailing of reinforcement. You do not need to memorise numbers; you need to insist that work is done "as per IS codes" and that a competent engineer is actually enforcing them.

Which brings us to supervision — the check behind all the other checks. A site with a qualified engineer or experienced supervisor physically present at critical stages (before concreting, during pouring, during curing) will catch problems while they are still fixable. A site left to labour alone will not. For an owner, the most valuable quality decision is not a fancy material — it is ensuring there is real, independent supervision at every pour. Insist on a simple quality checklist and a pour card signed off before concrete is ordered.