Tuesday, July 19, 2011

Week 25: Construction Update

View of the river and hills from the living room terrace
It is the month of July and we are right in the middle of monsoons in Goa. Monsoons in Goa bring with it torrential rains with gusty winds that sometimes continue for days without interruption. Most people agree that monsoon is the best time to be in Goa. Everything gets covered with a carpet of green. Plants grow several inches as if they were fed by artificial growth hormones. The sights and sounds of Goa in the monsoons are therapeutic in the most natural way.

Now let me tell you how it feels on our project site when it rains. First, you hear the rain approaching from a distance, rushing towards you. You see in a distance that the hills begin to blur from view. Then you can hear it above you but you miraculously remain dry due to thick tree cover. Finally, you start to feel a light spray of water that is escaping through the leaves. That is when you smile to yourself and decide whether to dash indoors for shelter or in the open to join in the fun...

From that romantic vision, let us turn our attention back to matters of construction, matters concerning brick, mortar and cement. As I explained in our last post, with the rains in full swing we are concentrating our energies to completing interior construction jobs. Last week on site, we completed the construction of internal partition walls in the main house. The material we have chosen for the internal walls is fly-ash bricks.

Fly-ash bricks being delivered to site
Fly-ash bricks are made with fly-ash that is a waste product from burning coal in power plants and sponge iron plants. This fly-ash when mixed with gypsum, lime (both also industrial waste products) and sand can be used to produce a viable building material in the form of fly-ash bricks. As a result, fly-ash bricks constitute 75% post industrial recycled material by weight. The performance properties of fly-ash bricks are also known to be comparable and in some cases better than regular brick, with high compressive strength, low water absorption, good thermal and sound insulation and no efflorescence.

The advantages of using fly-ash bricks are:
1. Recycling an industrial waste product for a new viable use. Fly-ash otherwise if not properly disposed is responsible for increasing air-pollution, making arable land infertile and contaminating water bodies.
2. Manufacturing of fly-ash bricks does not require firing. Fly-ash bricks are either sun-dried or steam dried. This eliminates the high energy use during the firing of regular bricks.
3. Reduces the need to quarry natural stone.
4. Fly-ash bricks are made locally in Goa about 50 kms. from our project site, reducing the embodied energy used in the transportation of the material to project site.

(Source for some of the above materials is an article written by Tallulah D'Silva on Fly-ash Bricks for Business Goa magazine, April Edition.)

Along, with fly-ash bricks, we have also chosen to use fly-ash cement in construction instead of regular Portland cement. It is not very well known but the production of Portland cement accounts for around 5% of global greenhouse gas (GHGs) emissions. It is estimated that the production of one ton of Portland cement produces about one ton of GHGs. Look out for more details in future posts on our use of fly-ash cement, load bearing walls and filler slabs in our effort to reduce the use of cement and concrete in this building.

Building partition walls with fly-ash bricks
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