Hot Weather Concreting

The intention of this article is to provide knowledge to general users with simple actionable works. To understand requirements, without going in to details of theoretical concepts, scientific and engineering analysis.

Concreting continuous throughout the year in construction industry but doing concreting in any extreme weather is a biggest challenge. Doing concreting in cold weather we don’t have much problem since concrete hardening being an exothermic reaction during cold weather.

To protect concrete from heat, common understanding of using chilled water is there or alternate is to do concreting in night shift. But with higher temperature in most part of the day, such strategy does not work for a durable concrete. General understanding in which concrete evaporates more than 1Kg/Sqm/Hr water.  It is perfect time to have a deep look in understanding hot weather concreting during summer.

Care during Designing

Care during Concrete Production

Care during Transportation

Care during Pouring

Care during Finishing surface and

Care during Curing

Care During Designing

Summer Concrete Shall be deigned with low heat of hydration materials.

PPC or Slag Cement, Low heat cement will help in many ways to have a good concrete with lower rate of reaction

Good quality Admixtures especially Polycarboxylic ether (PC) based can help to maintain good workability for relatively longer time and can also slowdown evaporation of water from concrete

Concrete shall be designed for the atmosphere in which the concreting is going to happen. (Maximum permissible fresh Pour Concrete is 35 Degree)

Care during Concrete Production

Care shall be taken to keep the fresh concrete temperature as lower as feasible. It is easier to care for fresh concrete rather than placed concrete

Mixing system shall not induce more heat and preferably insulation of mixing system shall be done

Cement (Bags) shall be stored in shaded area for sufficient time

Coarse aggregates shall be sprinkled with cold water

For Fine aggregates sprinkling of water if done shall be stopped couple of hour early to reduce moisture variation

For Higher temperature reduction, ice flakes shall be used

If ice flakes used shall be mixed with weighment to maintain the water cement ratio in line with design mix

Use of Liquid nitrogen is an option (Not Cost Effective and not feasible due to practical reasons)

Care during Transportation

Transportation time shall be kept minimum as much as possible (Batching location should be very nearer)

Transit Mixer drum shall be insulated to reduce the heat gain during transportation

Hessian cloth shall be used as an insulation material

Care during Pouring

During Pouring of concrete, pump pipe lines should be insulated to reduce temperature gain.

Dense Hessian cloth with sponge layer wrapping followed with wetting chilled water shall be done

Temporary shed shall be used for direct exposure to sun and wind. If shed is not feasible at least covering with thick plastic sheet shall be covered for shuttering and reinforcement before and during the concreting

Concrete pour area shall be water sprinkled (If Feasible) to cool shuttering and reinforcement. Care shall be taken that there is no standing water anywhere.

Care during Finishing surface

Late finishing shall be done before concrete starts being in semi plastic state

Evaporation reducing admixtures shall be used

Fogging of Concrete surface can be done during concrete green stage

Care during Curing. (Post Initial Set, Hardening of Concrete)

Once concrete can take a person’s weight, it is understood that concrete has initial set

Mist sprinkling of water can be done with a cover of hessian cloth

Water curing can continue either by ponding or intermittent watering surface

Time of form removal and start of curing is an important factor. Curing shall start with in 45 minutes of form removal

In short, Mass concreting during summer requires a detailed analysis, review and action plans for concrete care.