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.

Tips for Conserve Water

Dear Readers,

We are entering the Summer, already water crises are started in major cities. So, we should start saving the water we have and use the water we have, economically. Here are a few ideas on how to conserve water.

1. Almost all of us have reverse osmosis (RO) system installed at home for water for drinking and cooking. I am sure everyone knows that it lets out almost one litre water to produce one litre drinking water. So, keep a bucket to the outlet and store this water. This can very well be used for cleaning the floor, for toilet etc. What they normally say is, the bacteria which is there in this water will die in half an hour time when get exposed to normal air.
2. Similarly, a bucket can be placed in the AC outlet. Everyday morning this water can be used for the plants in your flat, to clean your cars or even be drained into the rainwater harvesting system so that the ground water can get charged. In fact, these outlets can be connected on a regular basis to get drained there.
3. Stop using running water for cleaning utensils and use water from bucket. By this practice lot of water can be saved.
4. Similarly use shower for bathing. This also would reduce water consumption.
5. Use your washing machine when you have a full load because washing machines are designed in such a way that it uses almost the same amount of water for washing low load to very high load.
6. If your washing machine's outlet is not connected to the closed drain. That is if the machine's outlet is let out in the bathroom, then the soap water which comes out of the machine can very well be used to soak your utensils which you have used for cooking.
7. 
   Some of us face a problem with dust in the water. For example, the borewell water may turn slightly muddy when the water bed goes down or because of the accumulated dirt in the overhead tank, the water may come with dust. Please don't waste this water. Keep a block of Alum in the bathroom. Just dip this in the bucket that has the muddy water and allow it to dissolve by rotating your hand. A few rotations will do. After about 10-15 minutes you will see the dust and muddy substances settled in the bottom and crystal-clear water in the top! This Alum would be available in all medical shops.

Co2 Blasting

Dear Readers,

Co2 Blasting is the new development is quickly expanding around the world. One system uses small rice pellets of dry ice shooting them out of the jet nozzle with compressed air.

It is known by several names like dry ice cleaning, Dry Ice blasting and dry ice dusting. It is a kind of carbon di oxide cleaning, where dry ice in the solid form of carbon di oxide, is accelerated in a pressurised stream and directed in the surface in order to clean it. This method is similar to other forms of abrasive blasting such as sandblasting, or soda blasting substituted for dry ice as a blasting medium.

This method is superior to sandblasting or Short blasting because the dry ice is soft enough not to pit or damage the underlying surface. Since the dry ice evaporates completely as a gas it leaves no wastes. Only the material being removed must be disposed of.

Dry ice blasting is the superior alternative to sand blasting, short blasting, soda blasting, water blasting and hand cleaning.

Advantages of Co2 blasting:

·       No preparation required prior to cleaning

·      No need to dismantle machines for cleaning. The pellets easily reach into the smallest nooks and corners.

·       Minimal machine downtimes

·       Environmentally friendly cleaning

·       Without additional chemicals or spray agents

·       Surface are not damaged

·       No residues