Currently, the construction industry produces significant amount of waste which generates more than 30% of the total industrial waste in many European countries. The large proportion of material waste generated in relation to materials consumed shows how waste has been unsustainably treated today. In general, this poor performance is due to dynamic and diverse characteristics of construction processes that cause inefficiency of resource use. Improvement in this area has been sought through various ways. In this respect, the use of 4D-CAD for efficient resource management and control is an area with great potential that has not been explored extensively. Current applications have shown positive results. For instance, the optimal install timings of building elements in construction can be suggested by connecting the construction process with digital objects to automate project visualization by means of animation. Thus, the potential for identifying inefficient planning solutions increases and improvement can be suggested. In addition, project progress can be monitored and managed through the whole construction process by comparing planning with as-build,
In this study, 4D-CAD was adopted for demolition project planning. In this respect, process simulation was used as an additional support to decision-making that is often reliant on experience. For that, the volume of generated waste and the optimal timing of resource movement were estimated quantitatively with 4D-CAD. Blender, a free 4D-CAD software, was used to develop an impact simulation tool for demolition projects. Physics and game engines were used to automatically simulate demolition in accordance with physics laws. In addition, Python programming was used in the development of a Graphical User Interphase (GUI). Simulation results for the time-lapsed impact change from two variables; i) machine use and ii) waste generation. Animation recorded in simulation is also useful for better understanding of users as a visual aid.
The testing of the tool involved the simulated demolition of a five-story building model created through BIM. Variables assessed included machine productivity for different demolition strategies and time-lapse change of waste generated. Time-lapse results of machinery productivity reveal the (in)efficiencies of different demolition processes. Waste generation data is classified by original (material) types and location; Waste distribution and purity levels are displayed on a demolition site map that forms the basis of a multi-factor waste recovery plan (e.g. machine transportation routes, collection order and timing). This process supports the definition of waste collection methods with increase purity levels and waste recovery rates. Limitations of the research includes the use of a simplified demolition method (e.g. single demolition machine and free-fall collapse).
In summary, the aim of this research is to enhance the recycling levels of demolition waste within construction. For that purpose, a simulation tool was developed to estimate and qualify waste from building demolition using BIM enabled 4D-CAD combined with physics and game engines. The studied variables were machinery impact and waste output within alternative demolition processes. In addition, Waste Distribution Maps (WDM) are generated to support decision-making. This research represents a significant advancement in applied computing for building demolition waste recycling and notably improves the quality of information available in the definition of building demolition strategies. Further steps of the research include to increase the level of precision of the impact analysis, waste distribution and waste purity to levels that support after demolition waste treatment decision-making.