Analysis of CO2 Emission Reduction Effect of On-Site Production Precast Concrete Member according to Factory Production Environment

Precast concrete (PC) method of construction is preferred for excellence in the reduction of construction period, lightweight, and durability and for PC member to be mostly transported to a site after its production in the in-plant production because the in situ production of the PC member is negatively perceived because of the limitation of space or production process being complex and difficult. However, if the PC member is produced on site and installed, it is possible to reduce the carbon dioxide emissions that are generated during shipping and loading and unloading, which are indirectly required for in-plant production. Carbon dioxide emission reduction effect due to the difference between the in situ production and in-plant production process of the PC member was confirmed by the existing studies, but the study of the carbon dioxide reduction effect according to various production environments of the in-plant production has not been performed. Therefore, the purpose of this study is to analyze the CO2 emission reduction effect of the PC member produced in site according to the in-plant production environment. As a result, it was found that when PC members were produced on site, there was an effect of reducing CO2 emissions by an average of 25.64% compared to factory production. In future, the results of this study will be used as basic data for establishing a CO2 emission reduction plan at construction sites.

Exploring the critical production risk factors for modular integrated construction projects

Purpose The factory production stage constitutes the bridge in the supply chains of modular integrated construction (MiC) projects. It embodies the fundamental differences between MiC and site-based construction. However, there is a poverty of knowledge of the uncertainties and risk events at the production stage. This study aims to investigate the critical production risk factors (PRFs) for MiC projects. Design/methodology/approach Comprehensive literature research and expert review identified and validated 22 candidate PRFs for MiC projects. A structured questionnaire survey was then used to gather opinions of domain experts in 18 countries on the relative impact of the validated PRFs for MiC projects. The collected data were analysed using multiple statistical techniques. Findings Statistical analysis identified nine critical PRFs for MiC projects. The top five include dimensional conflicts between modules during production; delays in production materials procurement; defective design; design information gap between designer and manufacturer; and limited capacity of manufacturers. Originality/value The study addressed the gap associated with identifying critical risk factors peculiar to the factory production stage of MiC projects. Its novelty lies in providing an opposite assessment of severities and prioritization of critical PRFs for MiC projects. The prioritized critical PRFs for MiC projects may inform resource allocation. Thus, it provides valuable information to MiC production specialists and project managers in their production risk planning and management strategies. The identified PRFs contribute to the theoretical checklist of MiC supply chain risk factors and may assist practitioners in assessing the severity levels of the PRFs of their MiC projects.

Analysis on Transporting Methods of Cultivation Unit for Vertical Cultivation in Plant Factory

Automatic transport can improve the operational efficiency in plant factory production and reduce the use of labor. However, a determination of a plant factory automation operation mode should comprehensively consider the economic strength of the enterprise, operation objects and operation mode, production scale, technical strength, labor costs, and other factors. In this study, a logistics transport system comprising a set of cultivation units was developed for plant factories, using a mode based on shelf-end delivery without power inside the shelf. Moreover, an analysis was conducted on four modes of common transportation methods for the cultivation units for vertical cultivation in plant factories. The results showed that, when comparing the progressive transport type and warehousing/reciprocating transport type for cultivation units, the transport productivity of the former is higher than that of the latter, and the difference in the two transport productivities is proportional to the capacity for cultivation units in each layer. When the capacities for cultivation units in each layer are 20 and 40, the transport productivity of the former is 115–200% and 130–250% higher than that of the latter, respectively. Moreover, the logistics transport system developed herein reaches an input (output) transport productivity of 330 (270) cultivation units h−1.

Concrete precast rejects – treatment, characterization, and application in new concrete as recycled aggregate

This article evaluates the feasibility of using concrete waste from precast production as recycled aggregate in concrete. The processing of concrete waste employed a jaw-hammer crusher and a sieve, producing three types of Recycled Concrete Aggregate (RCA). After their characterization, RCA was incorporated in two types of concrete used in the precast factory: a flowing concrete (FC), slump 220 mm, employed in columns and beams; and the second one, a no-slump extruded concrete (NSC), used for hollow core slabs. X-Ray diffraction, thermogravimetric analysis and scanning electronic microscopy showed phases from the hydrated cement paste and the original aggregate. Results of mechanical performance showed that RCA did not influence the compressive strength but influenced other properties such as water absorption and modulus of elasticity. Lastly, it was concluded that RCA obtained in the precast factory showed great potential to be used within the factory production process.

entire system of wages and rewards to increase productivity in factory

One of the latest tests to see whether one day or an industrial organization is functioning successfully or less successfully is the product units of that system. This assessment is not directly about the physical equipment, technology, or products of Japanese factories or about capital expenditures, and the stage of the companies being studied. However, there is a close relationship between social organization and the special attention currently paid to the question of productivity, apparently considering some special consideration of the problems which increase the effort to increase productivity in the large Japanese factories. Productivity - of course - is a relative measure, and the standard commonly used by Japanese executives is the output and cost of American factory production. In general, Japanese executives do not flatter their company when it comes to making such comparisons. Estimates need to be rough, and it can be difficult to mislead them to try to get an exact value. However, in comparing their factories to American factories producing the same goods, very few Japanese executives would speculate on a measure of productivity.