Concrete Curing Explained: Wetting Straw/Gunny Bags
In construction, after pouring concrete, a process called curing is essential to ensure the concrete gains strength and durability. The question describes a specific method where the concrete surface is covered with wet straw or gunny bags.
Purpose of Wet Curing Methods
This practice is a form of "moist curing". Let's break down why it's done:
- Hydration Process: Concrete hardens through a chemical reaction called hydration, where cement reacts with water. This reaction needs sufficient water and time to proceed properly.
- Preventing Water Loss: Fresh concrete contains water necessary for hydration. If this water evaporates too quickly (due to sun, wind, or low humidity), the hydration process stops prematurely. This can lead to weaker, less durable concrete.
- The Role of Straw/Gunny Bags: Covering the concrete surface with materials like straw or gunny bags and keeping them wet creates a barrier. This barrier significantly reduces the rate at which water evaporates from the concrete surface.
Analyzing the Options
Let's look at why the chosen method is performed:
- Option 1: prevent fast evaporation, until hydration has proceeded well This aligns perfectly with the explanation above. Keeping the concrete moist by preventing rapid water loss allows the crucial hydration process to continue effectively, leading to stronger concrete.
- Option 2: protect the concrete structure from contamination by dust particles While covering might offer some minor protection against dust, it's not the primary reason. Specialized covers are typically used if dust protection is a major concern. The wetting aspect specifically targets moisture retention.
- Option 3: prevent development of any fungus on the surface Fungus growth is generally not a primary concern in concrete curing. The focus is on the chemical and physical properties of the concrete itself, not surface biological growth.
- Option 4: give smoother and cleaner surface over cement structure Curing methods aim for strength and durability, not necessarily a smoother finish. While proper curing contributes to a better overall surface, the *main goal* isn't cosmetic smoothness or cleanliness achieved through this specific wetting technique. Other finishing techniques are used for surface appearance.
Conclusion
Therefore, the main reason for covering a new concrete structure with wet straw or gunny bags is to maintain adequate moisture content by preventing fast evaporation, ensuring that the cement hydration process can continue undisturbed until the concrete achieves sufficient strength.
Similar Questions
Which one of the following is used in soda-acid fire extinguishers?
After a hot sunny day, people sprinkle water on the roof-top because:
Methyl Isocyanate gas, which was involved in the disaster in Bhopal in December 1984, was used in the Union Carbide factory for the production of:
‘German silver’ is used to make decorative articles, coinage metal, ornaments, etc. The name is given because:
A patient's abdomen (alimentary canal) can be examined by X-ray after administering which one of the following metal salts in the patient's meal?
Which one among the following substances is a compound?
Which one of the following statements regarding acids is not correct?
Which among the following methods is used to separate the constituents present in compound?
- In which of the following colloids is the dispersing medium a liquid?
Match List-I with List-II and select the correct answer using the code given below the Lists :
List-I
(Trade Name)List-II
(Chemical Name)A. Bleaching powder 1. Sodium bicarbonate B. Baking soda 2. Sodium carbonate, 10 water C. Washing soda 3. Calcium oxychloride D. Plaster of Paris 4. Calcium sulphate, \(\frac{1}{2}\) water
Code:
A B C D
Important Questions from Chemistry in Everyday Life
Which of the following is a greenhouse gas?
I. Methane
II. Nitrous oxide
Which one of the following is used in soda-acid fire extinguishers?
The separation of two immiscible liquids can be done based on the difference in their_______.
Orange juice contains ______ acid due to which it tastes sour.
Impure water can be made pure
