Wet Curing Quantities for Slabs, Walls, Beams 2026
Concrete curing requires maintaining surface moisture preventing evaporation losses critical first 7 days achieving 95%+ hydration in cover zone. BS 8110 mandates 7-day wet curing horizontal surfaces, 3 days vertical with evaporation rates 0.5-3.0L/m²/day depending temperature, wind, humidity. Proper water quantities prevent plastic shrinkage cracking, surface dusting, and strength gradient ensuring durability against carbonation and reinforcement corrosion.
Horizontal slabs lose 1.5-2.5L/m²/day moderate conditions requiring ponding, hessian saturation, or continuous misting. Vertical walls consume 0.8-1.5L/m²/day accessible spray application with polythene sheeting alternative reducing labour 70%. Wind speeds above 15mph increase evaporation 50% necessitating windbreaks and frequent re-wetting maintaining continuous moisture film.
Evaporation calculated E = (25 + 19v)T RH formula where T=concrete temp °C, v=wind mph, RH=relative humidity producing 0.5L/m²/hr calm 20°C 60%RH rising 3.0L/m²/hr windy 30°C 40%RH. Critical first 4 hours post-finishing prevent bleeding water loss forming weak surface layer compromising abrasion resistance and carbonation protection.
Wet curing achieves 95% moisture retention through hessian (1.5L/m²/day), ponding (2.0L/m²/day), or mist sprays (1.0L/m²/day) most effective strength development. Curing compounds form 90% efficient membrane eliminating labour though unsuitable prestressed concrete requiring bond integrity. Polythene sheeting 85% effective vertical surfaces reducing water consumption 60% versus continuous spraying.
Curing water potable quality free oils, acids, sugars preventing hydration retardation or efflorescence. Chloride content <500ppm reinforced concrete avoiding corrosion acceleration. Seawater prohibited reinforcement contact though acceptable non-structural mass concrete distant steel with proven performance data.
Hessian saturation applies 2L/m² initial soaking refreshed 2-3x daily maintaining saturation without puddling. Continuous mist sprays 0.5-1.0L/m²/hour low pressure nozzles preventing rebound waste. Ponding slabs utilises temporary bunds 25mm depth recirculating water eliminating supply losses ideal large flat areas.
Site water bowsers 5000L capacity service 2000-4000m²/day moderate conditions with backup tanks preventing interruption. Rainwater collection supplements supply reducing costs 30-50% summer periods. Recycling spray runoff achieves 70% water efficiency though filtration essential preventing contamination.
| Surface | Rate L/m²/day | 7-Day Total | Method |
|---|---|---|---|
| Slab (20°C calm) | 1.5-2.0 | 10-14L/m² | Ponding/Hessian |
| Wall (20°C calm) | 0.8-1.2 | 6-8L/m² | Spray/Polythene |
| Beam Sides | 1.0-1.5 | 7-10L/m² | Mist/Compound |
| Column (4 faces) | 3.2-6.0 | 22-42L/m² | Sheeting preferred |
| Condition | Evaporation | Water Increase | Protection |
|---|---|---|---|
| Calm 20°C 60%RH | 1.0L/m²/day | 1.0x | Standard |
| Windy 25°C 40%RH | 2.5L/m²/day | 2.5x | Windbreaks |
| Hot 35°C 30%RH | 4.0L/m²/day | 4.0x | Mist + shade |
BS 8110 requires 7 days horizontal, 3 days vertical preventing surface carbonation and dusting.
Moderate conditions requiring hessian saturation or ponding maintaining continuous moisture.
15mph increases evaporation 50% necessitating windbreaks and frequent re-wetting.
Wet curing essential cover zone hydration achieving low permeability durability.
Standard capacity services moderate day slab curing with backup essential continuity.
Water quality potable standard preventing corrosion acceleration in reinforced elements.
Horizontal slabs require 1.5-2.0L/m²/day moderate conditions total 10-14L/m² over 7 days. Ponding most efficient recirculating water while hessian saturation traditional labour-intensive method both achieving required moisture retention preventing shrinkage cracking.
Seawater prohibited reinforced concrete curing due chloride corrosion risk though acceptable non-structural mass concrete >1m distant reinforcement with proven performance preventing long-term durability issues.
Hessian saturation requires 2-3 applications daily maintaining continuous moisture without puddling. Morning/evening cycles prevent daytime evaporation peaks ensuring consistent hydration throughout critical 7-day period.
Wind >15mph +50%, temp >25°C +30%, low humidity <50% +40% all accelerate evaporation requiring increased frequency/application rates or windbreaks/shade cloth maintaining surface saturation.
Curing compounds 90% efficient membrane vertical surfaces reducing labour 70% though unsuitable prestressed requiring full bond development. Polythene sheeting 85% effective eliminating water entirely ideal inaccessible areas.
Potable standard chloride <500ppm, pH 6-9, no oils/sugars preventing hydration interference or efflorescence. Site borehole testing essential non-mains supplies verifying suitability before large-scale curing operations.
5000L bowser services 2000-3000m²/day moderate slab curing with 2-day backup capacity preventing interruption. Rainwater harvesting supplements 30-50% summer reducing delivery costs and environmental impact.
Vertical walls 0.8-1.2L/m²/day accessible spray versus slabs 1.5-2.0L/m²/day ponding. Columns 4 faces multiply single face rate though sheeting preferred eliminating access/scaffolding requirements.
For curing compounds, visit BASF | Sika | For hessian, check Toolstation