Why not promote environment-friendly concrete?
Since its introduction back in 1845, concrete has become the most important item among construction materials accounting for 20% to 40% of total construction cost of a project. Be it for a residential building or for structures like bridges, flyovers, road pavements that are needed for the development of any country, concrete is an essential item that needs careful attention, more so for a country like Bangladesh.
Concrete has all along been a mixture of stone or brick chips, sand, cement and water, which holds good still to this day. But qualitatively there has been a revolution. While in earlier days concrete was of 1500 to 2000 psi strength in recent times it is up to 15000 psi (in our country up to 7000 psi). This is a remarkable achievement indeed.
The ingredients being primarily the same and consistent throughout, what is the trick that has made this revolution possible? It is knowledge and application of knowledge that has made it possible. It is high time that we accept concrete technology, a complex subject, to be studied with due seriousness and in a methodical manner.
At present in our engineering universities and technical institutes, concrete technology is a subject that constitutes a miniscule portion of the entire syllabus in civil engineering. With continuous growth of the use of concrete, application of lessons on the subject is rapidly diminishing. The process must be reversed quickly and effectively. The people concerned at high places, particularly the universities of engineering and technology, must give it a serious thought and introduce courses on concrete technology at different levels of civil engineering curriculum as a priority issue.
An important aspect of producing quality concrete is the process of mixing the ingredients. In the early days volumetrically proportioned stone/brick chips, sand and cement were dumped on ground, mixed together with a hand shovel, whereafter water was added and a homogeneous paste was prepared. Later on, engine propelled mixer machines got introduced to take over the process of mixing but the same volumetric proportioning of ingredients still persisted.
Gradually in the developed countries, this volumetric mixing was discarded and a system was developed to mix all the ingredients of exact weight as the concrete has been designed, where the amount of water to be mixed was also pre-designed and arrangement for achieving the same was incorporated. The concrete produced in this fashion has been termed 'Ready-Mix Concrete' which has now become a common term internationally.
The ready-mixed concrete, instead of mixing at site is produced at a suitable location from where it is transported to where it is needed. Apart from being a technically more sound a process, this has some distinct advantages namely --
* The production process is environment-friendly, free from cement and dust dispersion in atmosphere as well as it does not create a messy situation on the ground.
* Being located at a distance, it does not create a situation of sound pollution.
* Uncontrolled and hazardous storage of basic materials at construction sites causing traffic congestion and untidiness is avoided, keeping the environment congenial.
In all the developed countries, including our neighbourly developing ones like Thailand, Malaysia and Singapore traditional mixing has been banned and all concrete has to be ready mix. Even in India, particularly in its richer western part, the use of ready-mix concrete is as high as 35-50 percent whereas in our country it is still limited to 1-2 percent.
It was in 1991, ready-mix concrete was first introduced in our country by Concord Engineers and Construction Ltd, through establishment of a small plant at Tejgaon. It received no support from government. The situation continued for over 12-15 years, whereafter a couple of other entrepreneurs became aware of its necessity and potential and established batching plants (plans for producing ready-mix concrete) of their own. Still now its availability is limited to city areas of Dhaka and Chittagong only. With a little support from the government, this sector may develop quickly, which is needed for quality construction and environmental reasons.
Apparently ready-mix concrete is slightly more expensive than site mixed concrete as this has to be transported from a central plant to site and transportation has a cost. However this is not the real picture rather a superficial one. There are many elements that have an effect on the cost that are generally not noticed by an unaware user. Cutting wastage on site and labour cost in pouring and placement, saving time, particularly for large volume of concrete, facility of concreting at any time of day or night, not using cement more than actually required (it is ironical that most of our users even many of our engineers carry a misconception that extra cement, more than the design requirement, renders it to be better and finds this extra expenditure to be worthwhile) are just a few areas that remain unnoticed and ready-mix concrete is considered more expensive.
Imposition of VAT on ready-mix concrete, while site mix concrete is not subjected to the same, make it more unattractive to buyers. Such discriminatory move may hamper development and progress and not serve the best interest of the country.
It is now up to the policy and decision making people to take a highly important and necessary bold step of --
* Keeping ready-mix concrete out of VAT imposition say, for a period of 5 (five) years.
* Making it mandatory for all large government projects as well as constructions in big city areas to use ready-mix concrete, on both durability and environmental grounds.
If this is done, expansion of this budding industry will be manifold and once its use reaches a minimum of 25-30 percent of total production and use of concrete in the country, and VAT is imposed at that stage, the amount of VAT will be increased manifold and what is being sacrificed now for a much needed cause will be more than well rewarded, in subsequent years.
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