An Integrated Analysis of Aluminium Formwork Systems in Non-Standard Floor Plan Construction: Defectology, Labour Productivity and a BIM-Based Cost Estimation Model

Abstract

This paper presents a comprehensive case study of an 11-storey residential building constructed in Taipei, Taiwan, using an aluminium formwork system. The research establishes a detailed taxonomy of common concrete surface defects, quantifying their frequency and mapping their occurrence to specific structural elements. It was found that while defects are more prevalent in initial stages, a distinct learning curve leads to their reduction over successive floors. Secondly, this study analyses labour productivity, revealing that the Taiwanese construction team achieved an assembly rate of 5-7 m² per man-day, a figure that compares favourably with international benchmarks from India and Sri Lanka. Factors influencing this rate, including weather and geometric complexity, are examined. The primary contribution of this research is the development and validation of a novel labour estimation methodology. By leveraging Building Information Modelling (BIM), the study demonstrates that using a 'flat area' metric—the gross surface area ignoring openings—provides a more accurate prediction of labour requirements than conventional formwork contact area calculations. The findings confirm that despite higher initial investment and a steeper learning curve regarding defect control, aluminium formwork systems with BIM-automated drawings can reduce total construction costs by 31-53% compared to traditional timber methods.