POTENTIAL SOURCES OF WASTE IN CONSTRUCTION: INTRODUCTION:
Construction industry is the important source of waste production in the world almost in all the countries. The construction process currently generates significant quantities of waste: about a fifth of all waste and up to 40% of all solid waste is attributable to the construction sector. As much as 10% to 30% of construction material is wasted during construction . The formwork for cast-in-place concrete is one of the biggest sources of construction waste. Working on a temporary site, it is often difficult to arrange recycling logistics, and many subcontractors think it is better to deliver too much than too little. Moreover, mistakes in design can cause unnecessary demolishing and rebuilding. Hence the aim of the government is to minimize these wastes. Waste minimization is identified as one of the key factors for achieving sustainability. Some methods were invented for waste minimization such as use of software’s such as BIM, CAD etc. which are explained in detail in the upcoming paragraphs. Implementing any successful waste minimization strategy requires the assessment of the waste. Hence waste minimization has to be embedded as one of the project objectives for that lead to sustainability . The objective of this paper is to explore the sources of waste in construction and minimization of the waste using the BIM technique is evaluated. Sources of waste in construction:
Construction waste can be divided in to three main categories: 1. Material
3. Machinery waste.
The material waste is the main source in construction activity because most of the raw materials from which construction inputs are derived come from non-renewable resources. The term “waste” is a familiar term in the industry all over the world. The various sources of waste are evaluate below. Construction waste at site :
The level of waste at the site is considerable. From some studies, it was observes that the waste rate in Brazilian construction industry is 20 to 30% of the weight of total materials on the site. At the construction site the causes of waste are: poor handling of materials, inappropriate storage of materials, insufficient material storage areas, criminal activities, vandalism, poor quality of workmanship etc. * Handling of materials:
There are various types of materials in the construction activity e.g. bricks, coarse aggregate, sand, steel, timber, cement etc. and for each material the specified method of handling is recommended by the manufacturer, in order to prevent the damages due to mishandling. Hence the materials should be handled as per the specification given by the manufacturer in order to prevent the wastage. This is the most important when addressing the materials and components of high value per individual item as damage cost can be high on item basis . * Inappropriate storage of materials:
The method of storage of each material must be checked. The materials such as cement must be stored such that the place is free from moisture or else when subjected to moisture the cement particle tend to lose its fineness, quality and converts as a waste material such that it cannot be used for ever. This results in a heavy loss to the owner. Similarly for each and every material (bricks, aggregates, timber, steel etc.) the storage must be provided as per the specifications . * Insufficient storage areas:
This is nearly similar to the above but is caused through the lack of storage areas which will result in inappropriate storage being used as a result. Hence the site management must ensure that the storage areas for the required materials available and some materials are delivered to the site at any time and hence the storage areas for those materials are readily available all time .