Construction productivity improvement through industrialized construction methods

The construction industry has been pursuing industrialization for many years and it is getting momentum recently in many parts of the world with the rapid technological developments. Countries and regions like Australia, Germany, Japan, the Netherlands, Singapore, Sweden, the United Kingdom, the United States, and Hong Kong have been promoting the development and application of industrialized construction methods. Significant achievements have been achieved, such as improved construction productivity, better trades working environment, more environmentally friendly, etc. The main idea of industrialized construction is to manufacture and preassemble elements first in factory off-site and then transport them to the construction site for further assembly and installation into a whole building or part of it. A variety of technologies have been used in different regions of the world and in different periods of time, for example, off-site construction, prefabricated/precast construction, modular construction, modular integrated construction (MiC), and prefabricated prefinished volumetric construction (PPVC). In order to make the research more effective, from the nature of the problem, improving the productivity of critical construction trades is the most efficient way to increase the industry’s productivity. Therefore, the critical construction trades (CCTs) for both building and infrastructure projects are identified. In the method of industrialized construction, the working environment and working methods for CCTs have changed, especially for off-site construction. For off-site manufacture, precast production optimization is a method to improve the productivity. Genetic algorithm is used to solve the optimization model. It can provide better decisions than experience. Furthermore, many new technologies which are learned from manufacturing can be used in the construction industry. As a key technology of “Industry 4. 0”, 3D printing technology also has great application prospects in the construction industry. A case study of 3D printing bus station shows an increase in productivity using quantitative and comparative analysis methods. And then, for environmental impact, carbon footprint is widely used to evaluate the environment impact. A comparative analysis between construction 3D printing bus station and conventional bus station indicates that construction 3D printing technology has the potential to reduce the life-cycle carbon footprint and is more environmentally friendly. Apart from building and infrastructure projects, hydro-ecological restoration projects are also very demanding market for new technologies. Construction 3D printing technology with its key features (structures of complexity and the textures of heterogeneity) is very suitable for hydro-ecological restoration projects. To support this point of view, an experiment using 3D printing artificial reefs is conducted and the results which appraised by relevant agencies prove its effectiveness. The theoretical result concluded by this research provide construction stakeholders with the wisdom of improving construction productivity by industrialized construction methods. Identification of CCTs provide research emphasis. Precast production optimization model gives a better decision-making method for prefabricated component manufacture. Application of 3D printing technology into construction industry can inspire the future research.