Plastic Concrete Transportation Techniques on Construction Sites: A Comparative Productivity Study

Abstract

Target outputs on construction operations are of paramount importance to productivity studies in the built environment. The objective of this study therefore was to determine the target outputs of various methods of placing plastic concrete on construction sites as information for benchmarking concreting productivity in the Nigeria built environment. Using Lagos state as the study area, concreting operations were examined in 64 building construction sites spanning large-sized, medium-sized and small-sized construction companies with 8,34 and 22 projects respectively. Using stratified random sampling, 25 of the 64 sites were selected for investigation and were made up of 5, 10, 10 sites for the respective large, medium and small-sized construction firms. The study was limited to bungalows and single storey residential, commercial and office building sites managed by construction companies registered with the Federal or Lagos State Ministry of Works only. A total of 167 daily concrete pours was observed on the 25 construction sites at an average of 6 days per site. Data collected included placing method, location/type of concrete pours, quantity of concrete placed, overall pour time, number of operatives engaged, and actual duration of concreting, distance to pour location, weather and delay time. The results showed that the four main concrete placing techniques used in Lagos State were cranes, dumpers, wheelbarrows, and head pans. The mean overall concreting productivity of cranes was 11.24 m³/hr compared to 8.53 m³/hr by dumpers, 6.69 m³/hr by wheelbarrows and 3.21 m³/hr by head pans. The labour productivity for concreting by cranes was 4.09 whr/m³ as against 5.13 whr/m³ for dumpers, 9.74 whr/m³ for wheelbarrows and 12.11 whr/m³ for head pans. The productivities were in the ratio of 4:3:2:1 for cranes, dumpers, wheelbarrows, and head pans respectively.  The results have significant bearing for contractor’s method statement and tend to guide construction clients in adjudicating tenders for selecting the contractor who can best manage the technical risk associated with the construction project.

Keywords: Plastic concrete, transportation techniques, construction sites, productivity.