MATERIALS WASTAGE: CAUSES AND THEIR CONTRIBUTIONS LEVEL.

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1 MATERIALS WASTAGE: CAUSES AND THEIR CONTRIBUTIONS LEVEL. Oladiran, Olatunji Joseph. University of Lagos, Akoka Yaba, Lagos, Nigeria. ABSTRACT. This study investigates the existence of certain predetermined causes of materials wastage and their degree of contributions to materials waste generation (MWG) in building projects. The population of the study consists of construction professionals in building projects in Lagos state, Nigeria. The survey involves the usage of a designed questionnaire to elicit information from the targeted population via convenience sampling method. The data were analysed using frequency, mean score and t-test. The research confirms the existence of all the predetermined causes of materials wastage in Nigerian building projects. It also reveals that these causes contribute significantly to MWG but at different level on Nigerian building projects. Poor supervision contributes most to materials waste generation while bulk purchases is least among all the causes. The study therefore recommends that practitioners should be cognizant of these causes of materials waste and introduces measures to curb them to minimize MWG. KEYWORDS: MWG, causes, contributions, Nigeria. INTRODUCTION. Chadwick (1982) views materials as one of the scarce resources usually required for in the erection or construction of physical infrastructure. He adds that the cost profile of materials forms about 51% by cost of construction. Oladiran (2008b) defines construction wastes generally as excess resources used (which includes materials) than required for construction production. In this regard, Ekanayake and Ofori (2000) views materials waste as any materials, apart from earth materials, which needs to be transported elsewhere from the construction site or used within the construction site itself for the purpose of land filling, incineration, recycling, reusing or composting, other than the intended specific purpose of the project due to materials damage, excess, non-use, or non-compliance with the specifications or being a by-product of the construction process. The quality of materials used and the management of material waste in building projects are of paramount importance. Obviously, the control of quality of materials used leads to savings from materials wastage. It is generally an accepted phenomenon that not all the materials requested and delivered to construction sites are used for the purpose for which they are ordered. Also, contractors often use sub-standard materials after billing their clients with standard material s cost. Due to lack of control, these materials are either lost or the quality is not met. Chandrakanthi et. al (2002) report that growth in construction activities increases the amount of

2 CIB W065/055 Commissions: Transformation through Construction 2 construction waste generated. Also, Andy et al (2002) discover that over 70 million tonnes of waste is generated in the construction industry yearly, which amounts to 24kg per week for every person in the UK, about four times the rate of household waste production. Waste costs money at any level of the construction and should be the concern of all the parties in the construction team as it gives rise to loss of resources. In respect to this, this study is focused at investigating the causes of materials wastage and their contribution to materials wastage on building projects. RESEARCH HYPOTHESIS. A null hypothesis was postulated for the study, which is: causes of materials waste have no significant contributions to materials waste generation on building projects. LITERATURE REVIEW. Construction Waste Management. Chandrakanthi et al (2002) reports that a high proportion of municipality waste is construction related, so its reduction becomes important. According to them, construction companies benefit in reducing waste generation by reducing transportation and landfill deposition costs, and the purchasing costs of virgin materials. They add that waste production at a construction site may result from a lack of attention being paid to the size of the product used, lack of interest of contractors, and lack of knowledge about construction during design activities. In this vain, Bossink and Brouwers (1996) discover that about 1-10% by weight of the purchased construction materials depending on the type of material leaves the site as waste. According to them, about 50 to 80% of the construction waste can be reused or recycled. They state further that in terms of sustainability, construction waste management and reduction can be considered an issue that focuses on the danger of depletion of materials used in the construction industry such as timber, sand and gravel. It is also a common practice to transport construction waste to landfills. Construction and demolition waste as a percentage of all solid waste that enters landfills in various countries as reported by them are outlined in Table 1. The importance of the construction waste management is illustrated by the data in Table 1. Similarly, identification of the composition of waste is also relevant for an efficient waste management process due to the amount of waste that is reusable. Hence, Hettiaratchi et. al (1997) examine construction waste composition in countries from Europe and United States which yield data summarized in Table 2.

3 CIB W065/055 Commissions: Transformation through Construction 3 Table 1: Construction and Demolition Waste as percentages of all Solid Waste entering Landfills. Country Construction and Demolition Waste (by weight) in percentage (%) United States 26 Australia The Netherlands Germany 19 Finland Source: Bossink and Brouwers (1996) Table 2: Composition of Construction and Demolition Waste. Construction & demolition Waste Category Composition (by weight) in % Bossink & Spencer Brouwers AEP (1991) (1996) (1995) CH2M Hill (1992) Asphalt 46 Concrete Metal Wood Clay stone Tablets 29 Concrete and Wood piles 17 Clay Bricks 14 6 Clay roof tiles 10 Cement Mortar 8 Paper / cardboard packing material 7 8 Rubble, Aggregate, Ceramics & 24 Concrete Building materials like Gypsum 17 2 Board Glass 3 Plastics 2 Other mixed C & D Waste Total Source: Hettiaratchi et al (1997)

4 CIB W065/055 Commissions: Transformation through Construction 4 Waste Minimization Strategies. Andy et al (2002) define waste minimization as any technique that avoids, eliminates or reduces waste at its source. Designing out waste at the earliest stage of the construction process offers the greatest opportunities for waste minimization. They state further that best management approach to waste, particularly hazardous waste, is to manage the process so that there is no waste to manage. The process of waste generation through design is complex when a single product, a building system for example can have a large number of materials and processes to realize the product. The issue is made more complex when further creators of waste are added during subcontract and construction phases. Many variables and restraints affect the design that in turn affects the wastes arising and the resultant opportunities for designing out waste. Such variables include materials, choice, and component complexity, building complexity, co-ordination, fast tracking and communication (Andy et al., 2002). According to them, one must identify the route of the waste, whether its origins are in concept, scheme or detail design and what disciplines are involved. It is then necessary to adopt a waste reduction approach to address the cause of this issue. This approach includes: Use of prefabrication and off-site prefabrication, standard component, realistic component size, capacity and specification, minimizing temporary works, optimizing design lives, designing for recycling and ease of disassembly, identification of materials which create waste and poor communication. Also, the process of designing out waste must be integrated within the project process to ensure its success. In this regard, Akindoyeni (1989) states that in order to reduce waste, the designers decisions need to be carefully described in the specification documents. This document communicates to the supplier the quantity of materials and to the operative the care that must be taken in fixing the materials. On the other hand, Chadrakanthi et al (2002) categorize waste on construction sites as metal, wood, drywall, concrete and other wastes, which can be reduced using a Special Purpose Simulation (SPS) model that was developed by Hajjar and Abourizk (2000). RESEARCH METHODOLGY. A questionnaire was design to elicit the required data to achieve the objectives of the study. The population of the study consists of construction professionals in building firms in Lagos state, Nigeria. A sample size of 40 respondents, selected through convenience-sampling method was used for the research. Table 3 reveals the type of organizations while Table 4 sheds light on the construction experience of the respondents for the study. Table 3: Types of Organizations. Organizations. Frequency Contracting 19 Consulting 13 Teaching/Research 7 Total 39

5 CIB W065/055 Commissions: Transformation through Construction 5 Table 4: Respondents Construction Experience Years of work experience Frequency Below 5 years years years years 7 Above 20 years 5 Total 40 As many as 29.7% of the respondents are Civil Engineers, 37.9% are Builders, 21.6% are Architects and 10.8% are Quantity Surveyors. This shows a trend that Builders dominate the building firms. Similarly, 21 respondents are HND/BSc holder, 16 are M.Sc holders, 2 are NCE/OND holders and just 1 is a Ph.D holder. In addition, 30.6% of the respondents are corporate members of Nigerian Institute of Building (NIOB), 27.8% each are of Nigerian Society of Engineers (NSE) and Nigerian Institute of Architects (NIA) while 13.9% are of Nigerian Institute of Quantity Surveyors (NIQS). Thus, the respondents are capable both academically and professionally to provide the required information for the study. The questionnaire also sought the opinions of the respondents on a list of predetermined causes of MWG, derived from the opinions of the researchers and other professional practitioners in building production. The respondents opinions on the existence of these causes in building projects were sought and their contribution to MWG were measured on a likert scale. In the scale, 1 implies very low, 2 implies low, 3 implies average, 4 implies high, and 5 implies very high. Mean scores and ranking were used to determine the causes level of contributions to MWG.Similarly, one-sample t-test was used to examine the significance of all the causes in generating materials waste. FINDINGS. Causes of Materials Wastage and their level of contributions to Materials Waste Generation. Table 5 shows the various causes of material wastage on building projects and their different contributions to materials waste generation as signified by the respondents. The Table reveals 13 causes with their varying contributions to materials waste generation. It can be inferred from the Table 5 that Poor supervision contributes most to material waste generation on building projects. This is followed by design error and all the respondents opined that bulk purchase that results in excess is the least. This result is partly similar to the causes of MWG highlighted in Illigurth (2000). Poor supervision is perhaps the chief cause because Nigerian construction projects are rife with the presence of quacks. Professional Builders that are specifically trained for building production are not involved in some projects and are not adequate where they are involved.

6 CIB W065/055 Commissions: Transformation through Construction 6 Similarly some of the projects are not even designed by Architects and other requisite professionals but by quacks and hence specification errors, design errors and changes which induce materials wastes. In addition, Nigerian construction industry is currently faced with the problem of lack of adequate skilled operatives, which perhaps is responsible for the use of unskilled labours. One of the respondents noted that the usage of defective and wrong quality materials is largely as a result of tendering at lower cost because in most cases the lowest bidder gets the job. Nigerian clients are more concerned about cost than any other thing at the tendering stage. It can also be observed from Table 6 that all the causes have significant contributions to materials waste generation on building projects. This is because the t cals for all the causes are greater than the t tab at 95% confidence interval. Hence the research hypothesis, which states that causes of materials waste have no significant contributions to materials waste generation on building projects, is rejected. Therefore all the causes contribute significantly to materials waste generations. This is perhaps so of all the causes due to the reasons mentioned earlier. Table 5: Causes of Materials Wastage and their level of contributions to MWG. Causes of materials wastage N Level Of Contributions MIS Rank Poor supervision Design error Defective materials Unskilled labour Wrong quality materials Changes in design Specification errors Poor storage facilities Poor handling process Poor material scheduling Poor product information Wrong suppliers advice Bulk purchase which leads to excess N = Number of respondents 1 = Very low 2 = Low 3 = Average 4 = High 5 = Very high

7 CIB W065/055 Commissions: Transformation through Construction 7 Table 6: One-Sample t-test for causes of MWG. Causes N Mean df t cal Poor supervision Design error Defective materials Unskilled labour Wrong quality materials Changes in design Specification errors Poor storage facilities Poor handling process Poor material scheduling Poor product information Wrong suppliers advice Bulk purchase which leads to excess Note that Test is at 95% confidence interval and t tab is CONCLUSION AND RECOMMENDATIOS. The study reveals from Table 5 that the followings causes of materials wastage exist on Nigerian building projects: Wrong quality materials. Bulk purchase, which leads to excess. Wrong suppliers advice. Unskilled labour. Changes in design. Specification errors. Design errors. Poor supervision. Poor product information. Poor handling process. Poor storage facilities. Defective materials. Poor material scheduling. It also reveals from Tables 5 and 6 that these causes have varying and significant contributions to materials waste generations on building projects in Nigeria. Due to these findings, in order to minimize materials waste generation on building projects, it is recommended that: Practitioners should be cognizant of these causes of materials waste and introduce measures to curb them. Design changes, specification and design errors should be avoided or minimized. Adequate supervision by requisite building professionals should be promoted and skilful operatives are used.

8 CIB W065/055 Commissions: Transformation through Construction 8 Good building materials with proper storage facilities and handling processes are used. Products information and advices are sought directly from manufacturers and experienced suppliers. Practitioners should endeavour to use proper materials scheduling and avoid excess bulk materials purchase. SHORTCOMINGS. The first limitation is that only 40 respondents on building sites are used which appear to be small considering the large number of building sites in Nigeria. There are 36 States and Federal Capital in Nigeria and all the respondents are just from one State (i.e. Lagos State-the research area). There is therefore the likelihood that these sites are not truly representative of the population. Hence, generalizing the findings to the Nigerian building sites must be done cautiously. The second limitation is the possible biases that might be introduced when respondents answer some of the questions. For example, the levels of materials waste contributions of the predetermined causes were measured on a Likert scale. These subjective responses may not have been rated unbiasedly. Thirdly, the respondents may not have been able to supply all the information on the causes of materials waste because their opinions was only sought on predetermined causes. This will limit the amount of information on the causes of materials waste received from them for the research. FURTHER STUDIES. The weaknesses of this research noted above are not expected to nullify the results but rather point our attention to, inter alia the undermentioned areas of future research: 1. A repeat study in Nigeria of wider research area, with a larger sample size and possibly with a probabilistic sampling method for proper representativeness. 2. Objective measurements of the level of contributions to materials waste generation by various causes. 3. Empirical surveys involving the usage of open-ended questions to identify the sources and causes of materials waste with their level of contributions. This will reflect in detail the actual sources and causes of materials waste in Nigerian building projects. 4. The actual materials waste generation s level in Nigerian projects should be examined and determined quantitavely. This will properly reveal the problem of materials waste in Nigeria and proffers leads toward minimizing it and sustainability.

9 CIB W065/055 Commissions: Transformation through Construction 9 REFERENCES. Akindoyeni, A. (1989). Quality control in construction and maintenance. Proceedings: 20 th Annual Conference of the Nigerian Institute Of Building. Andy, K., Andrew, B., & Simon, A. (2002). Designing to encourage waste minimization in the construction industry. Journal of the Department of Civil and Building Engineering, Loughborough University, Leicestershire, UK. Bossink, B. A., & Brouwers, H.J. (1996). Construction waste quantification and source Evaluation. International Journal of Construction Engineering and Management, 1(221). Chadwick, L. (1982). Material management profitability and the construction industry. Journal of Building Technology and Management, 2(8). Chandrakanthi, M., Hettiaratchi, P., Prado, B., & Ruwanpura, J. (2002). Optimization of waste management for construction projects using simulation. The proceeding of the 2002 winter simulation conference, Ekanayake, L.L., & Ofori, G. (2000). Construction materials waste source evaluation. Proceedings: Strategies for a sustainable built environment, Pretoria, August. Hajjar, D., & Abourizk, S. (2000). Application framework for development of simulation tools. Journal of Computing in Civil Engineering, 14(3). Hettiaratchi, J. P., Ajward, M. H., Joshi, R.C., & To, M. (1997). Construction and demolition of waste. Proceeding of the International Conference on Engineering Materials, CSCE, Ottawa. Illigurth, J.R. (2000). Waste in the construction process.2 nd Edition. EF&N Spon: London Oladiran, O. J. (2008b). Lean -In- Nigerian Construction: State, Barriers, Strategies And Go- To-Gemba Approach. Proceedings of the IGLC 16, Manchester, UK..