Page 26 - GRIHA Manual Volume IV - Introduction to National Rating System
P. 26
Building planning and construction 17
CRIteRIon 12
effICIent use of wAteR
duRInG ConstRuCtIon
Introduction
The Indian construction sector is a water-intensive industry. An estimated water demand of 10%–
20% of the total volume of brick and cement is observed during construction. Water required for
construction needs to be pure in order to achieve the desired strength. Otherwise, it may have a
serious negative impact on the life of the structure.
Almost all stages of the construction work require water—for foundation, brick-soaking, masonry,
curing, concreting, white-washing, painting, and mosaic flooring. Given the average growth rate
of 10% in the construction sector, there is an urgent need to bring down the water demand by
appropriate means without compromising on the quality of the construction work. This criterion
is intended to reduce the demand for potable water during the construction phase of a building.
Solution
Strategies for reducing the demand for potable water during
construction
1. Concrete mixtures containing fly ash generally require less water (1%–10% less) for a given
slump than concrete containing only Portland cement. Similarly, ground slag decreases water
demand by 1%–10% depending on the amount used. An added advantage of lesser bleeding
and segregation than plain concrete is also achieved. The water requirement increases with
increasing fineness and carbon content of fly ash.
2. The purpose of moist curing is to prevent evaporation of the water added originally to fresh
concrete and preserve it for the purpose of hydration. The quality of curing water used should
be as good as the mixing water. Vertical surfaces such as walls and columns lose curing water
fast and, hence, it is preferable to retain the formwork
longer or use very frequent wetting. Moist curing
prevents loss of moisture from concrete, as well as
maintains a satisfactory temperature regime. The
curing regime prevents the development of high
temperature gradients within the concrete. Traditional
methods such as the use of gunny bags, which are
permanently damp with adequate water, is one of
the ways for curing the concrete laid for the first 7–10
days, to attain strength. When concrete is made, either
with mineral admixtures or blended cements, curing Figure 1 Use of gunny bags for curing of
columns and slab
period should be extended to 14 days.
CRIteRIon 12
effICIent use of wAteR
duRInG ConstRuCtIon
Introduction
The Indian construction sector is a water-intensive industry. An estimated water demand of 10%–
20% of the total volume of brick and cement is observed during construction. Water required for
construction needs to be pure in order to achieve the desired strength. Otherwise, it may have a
serious negative impact on the life of the structure.
Almost all stages of the construction work require water—for foundation, brick-soaking, masonry,
curing, concreting, white-washing, painting, and mosaic flooring. Given the average growth rate
of 10% in the construction sector, there is an urgent need to bring down the water demand by
appropriate means without compromising on the quality of the construction work. This criterion
is intended to reduce the demand for potable water during the construction phase of a building.
Solution
Strategies for reducing the demand for potable water during
construction
1. Concrete mixtures containing fly ash generally require less water (1%–10% less) for a given
slump than concrete containing only Portland cement. Similarly, ground slag decreases water
demand by 1%–10% depending on the amount used. An added advantage of lesser bleeding
and segregation than plain concrete is also achieved. The water requirement increases with
increasing fineness and carbon content of fly ash.
2. The purpose of moist curing is to prevent evaporation of the water added originally to fresh
concrete and preserve it for the purpose of hydration. The quality of curing water used should
be as good as the mixing water. Vertical surfaces such as walls and columns lose curing water
fast and, hence, it is preferable to retain the formwork
longer or use very frequent wetting. Moist curing
prevents loss of moisture from concrete, as well as
maintains a satisfactory temperature regime. The
curing regime prevents the development of high
temperature gradients within the concrete. Traditional
methods such as the use of gunny bags, which are
permanently damp with adequate water, is one of
the ways for curing the concrete laid for the first 7–10
days, to attain strength. When concrete is made, either
with mineral admixtures or blended cements, curing Figure 1 Use of gunny bags for curing of
columns and slab
period should be extended to 14 days.
