Concrete Work in Hong Kong Island

You can usually walk on it after 24-48 hours, drive on it after about 7 days, and it reaches design strength at 28 days. Curing (keeping it damp, protecting from frost or extreme heat) in the first week matters more for durability than almost anything else.

Concrete is priced by area and thickness for slabs (per m² or sq ft), by volume for supply (per cubic metre/yard), and by the job for repairs. The concrete itself is often less than half the bill — formwork, reinforcement, sub-base preparation, finishing and access drive the labour cost.

Look for crews who do concrete daily, not general handymen — finishing is a perishable skill and a two-hour window decides how the slab looks forever. In Hong Kong Island, ask for addresses of slabs poured a few years ago and look at the joints and edges, which is where poor work shows first.

Excavation and sub-base, formwork, reinforcement (mesh size or fibre dose), concrete grade and thickness, the finish (broom, trowel, exposed aggregate, stamped), control joints, curing method, and spoil removal. Any quote that just says 'supply and lay concrete' leaves too much undefined.

Hairline shrinkage cracks are normal; that is what control joints are for — they give cracking a straight place to happen. Wide, uneven or lifting cracks signal a base, reinforcement or curing problem. If a new slab cracks outside its joints within months, call the contractor back.

Common rules of thumb: 75-100mm (3-4") for paths and patios, 100-125mm (4-5") for driveways and garage floors, more for heavy vehicles — always over a compacted sub-base with mesh or fibre reinforcement. Thin slabs on soft ground crack no matter how good the finish looks.

Strongly. Frost can ruin an uncured pour, extreme heat causes plastic shrinkage cracking, and rain marks fresh surfaces. Good contractors watch forecasts and will delay a pour; be suspicious of anyone happy to pour into bad weather to keep the schedule.

Decades-old reinforced concrete plus humid, salty air corrodes rebar, which expands and pops the cover concrete. Proper repair means breaking out to sound concrete, treating the steel, and rebuilding with repair mortar — patching over it just delays the next fall of concrete.