Electrical installations running through masonry walls: developing waste generation indicators for environmental performance analysis

Waste generation is one of the most relevant environmental aspects of the construction industry. About 47 million tons of construction and demolition waste are collected annually by Brazilian municipalities. One of the activities that generates waste is cutting chases on walls for installations. However, there are no waste generation indicators for this activity. Understanding waste generation processes enables managers to prevent them and promote their proper environmental management. This study assessed the generation of waste resulting from the cutting of clay bricks for electrical installations using three tools: milling cutter, marble saw, and cold chisel. The study included data collected from residential construction works and experimental data collected from the construction of real-scale walls. In a laboratory, five different wall configurations were built and the three tools mentioned were used to cut a chase on the walls. The results were statistically analyzed to define a waste generation index (WGI) by linear regression. The type of tool employed had no influence on the waste generation index, which was 26.5 +/- 2.6 kg/m2. However, the tools used directly influenced the quality of the service, productivity, and the volume of waste generated. The waste from the milling cutter showed the smallest maximum aggregate size and the largest bulk density, followed by the waste resulting from the marble saw and the cold chisel. The marble saw and cold chisel waste samples had around 78% of their composition in the coarse aggregate grain size range. The milling cutter waste samples were the finest and had on average 60% of their composition in the fine aggregate grain size range. The width of the chases made with the milling cutter were smaller and more consistent than those made with the cold chisel, which showed irregularities and larger dimensions than necessary. From the waste generation indicators obtained in this study, construction managers will be able to choose more appropriate cutting tools and improve their planning and management systems to minimize associated environmental impacts.