Curing: To keep all construction works wet; small or big such as brick work, cement concrete, cement plaster etc. in which cement is used, is called curing. It’s an important aspect of construction work and is especially most important in case of cement concrete work. Properly cured cement concrete is hard, stronger and durable.
General Practical Observations
In actual practice the picture is totally different, though curing work looks so simple yet it is ignored most of the times. Here are a few examples of not doing proper curing.
1. Govt. work: Even after having knowledge for the importance of curing in cement concrete work, most of the officers take this part casually and pass this responsibility to juniors. The junior officers would then pass this responsibility to supervisors who ask contractor foreman /sight in charge for curing and so on.
When any officer inquires of curing work from supervisors, his standard reply is that he asked contractor labors and they are doing curing work.
Labor contractors also save the labor and just spray water in the morning and whenever asked by any officer, his standard reply is that he has poured the water twice or thrice since morning. No one bothers to look at curing work on the spot in one’s presence.By ignoring curing work they encroached the strength of the concrete reducing the factor of safety and life of the concrete.
2. Private Work: In private construction house owner does not know about the importance of curing work and he has not much time to see curing work. As earlier stated that contractors’ labor just spray water in the morning. The water evaporates after sometime and the concrete becomes dry till the evening. It is at his good will if he remembers to spray water or not in the evening
Let me repeat here that curing must be done 3 to 5 times a day so that the concrete is wet 24 hours a day otherwise the strength of the concrete would reduce up to 50%.
Let me highlight one glaring incident that had happened due to not attending to curing and it caused extensive loss to the following.
1. To the structure
2. To the reputation of a leading water tank contractor of the state.
3. To the career of engineers responsible for supervision.
I am writing about this episode here to CAUTION all involved in construction work to the importance of curing.
A couple of years ago a huge over head water tank of 15 lacs liters capacity having 25 meter height was under construction by contractor with his own design in coastal town in Andhra Pradesh.
The fault of the contractor was that he did not depute technically qualified and experienced person to supervise the work.
The concrete of a huge RCC top dome was done in the month of March when the sun is very hot in the area and heavy winds blow throughout the day. As usual all felt relaxed that the last part of the work was completed but they all ignored about the importance of proper curing.
The Engineer left the site after giving instructions for curing. The person in-charge of the work instead of making proper arrangement for curing in his presence left the site for his home town simply telling the labor to do curing regularly. The labor took the job of curing casually as he was ignorant about the importance of curing for RCC work.
There was no arrangement of water pump for curing at the site. There were three or four ‘laborers/Beldars’ available at site and rest of the labor was skilled labor and they did not co-operate ‘laborers/Beldars’ in manual curing. ‘laborers/Beldars’ later complained that the rope for pulling the water bucket swings in all directions due to heavy wind and they could not do curing at 25 meter height. On that height they were afraid to climb. As a result not a drop of water was poured on the surface of dome after concreting. Any responsible/ knowledgeable/ person would have arranged for curing anyhow but no one was present on the site and they all thought that it was being done by someone else.
The departmental officer had faith on contractor and contractor thought that his supervisor would do curing work and therefore no one tried to check and ascertain that concrete laid was properly cured or not. It is certain that the nature does not spare any one whether the fault is committed or omitted, it has to take own toll quietly.
After four or five days of opening the shuttering/form work , the top and side of dome collapsed suddenly when the laborers were away from the site due to lunch break. The accident was not fatal which saved the contractor and Govt. official from legal troubles.
The main purpose of citing the above incidence is to show how the matter of curing though looks to be small and simple yet is almost neglected by a lot of contractors /Engineers /Architects. This is a deadly mistake!