You can order the right grade, pour it perfectly and still end up with weak, cracked concrete if it isn’t cured properly. Curing is the simplest step in concreting, and the one most often cut short.
Here’s how to cure concrete properly, with tips for Kerala’s hot summers and heavy monsoon.
Why curing matters
Concrete doesn’t harden by drying out. It gains strength through hydration, a chemical reaction between cement and water that continues for weeks. If the surface dries too early, hydration stops near the surface. The result is a weak, dusty top layer, more shrinkage cracks and concrete that lets water reach the steel reinforcement more easily.
When to start
Start as soon as the surface can take it without damage, usually once it has set enough that water or a covering won’t mark it. In the first hours, protect the fresh surface from direct sun, wind and heavy rain with sheets or covers; then begin wet curing.
How long to cure
IS 456 gives minimum curing periods for exposed concrete surfaces:
- At least 7 days for concrete made with ordinary Portland cement
- At least 10 days where mineral admixtures or blended cements are used (for example fly ash concrete or PPC), and for concrete exposed to dry and hot weather
- For mineral admixtures or blended cements, extending curing to 14 days is recommended
Longer curing is never harmful. If in doubt, keep going.
Curing is part of quality, from the plant to your site. See how we test every batch →
Curing methods
- Ponding: small bunds of mortar or sand around a slab hold a layer of water. Very effective for flat slabs.
- Wet hessian or gunny bags: good for columns, beams and walls. Keep them wet all the time.
- Sprinkling: works only if it keeps the surface continuously wet, not just once or twice a day.
- Plastic sheeting: traps moisture; overlap and weigh down the edges.
- Curing compounds: sprayed membranes that slow evaporation, useful where water is scarce or surfaces are hard to keep wet. Follow the manufacturer’s instructions and check compatibility with later finishes.
Kerala’s climate: what to watch
Hot, sunny days
In the summer months, sun and breeze can dry a slab surface within hours. Plan pours for early morning where possible, protect the surface quickly and keep curing water continuous through the hottest part of the day.
Monsoon rain
Rain helps keep hardened concrete wet, but heavy rain on freshly placed concrete can wash cement from the surface and spoil the finish. Keep plastic sheets ready, check the forecast, and talk to us early if you need to reschedule a pour.
Columns and vertical surfaces
Water runs off vertical faces, so wrap columns in wet hessian or sheets rather than just splashing water on them.
Common mistakes
- Stopping after two or three days because the concrete “looks hard”
- Letting the surface dry out between waterings, causing repeated wet-dry cycles
- Curing the top of a slab but forgetting edges, beams and columns
- Removing formwork early and leaving the newly exposed faces uncured
Key takeaways
- Concrete gains strength through hydration, which needs water.
- Cure for at least 7 days (OPC) or 10 days (blended cements, hot dry weather); 14 days is recommended for blended mixes.
- Keep surfaces continuously wet; wet-dry cycles defeat the purpose.
- Protect fresh concrete from strong sun and heavy rain in the first hours.
Frequently asked questions
Can I stop curing once the slab looks hard?
No. Concrete hardens on the surface long before it has gained its full strength. Continue for the full curing period.
Is rain enough to cure a slab?
Steady rain on hardened concrete helps, but it isn’t reliable, and dry spells between showers break the curing. Keep your own curing in place throughout.
Does ready-mix concrete need less curing?
No. Curing needs are set by the cement type and conditions, not by where the concrete was mixed. Ready-mix gives you a consistent mix; curing on site still decides how much of its strength you get.
