Browsing by Author "Podges, Tian Martin"

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    A decision model for the investment in technology to reduce concrete rework
    (Stellenbosch : Stellenbosch University, 2017-12) Podges, Tian Martin; Wium, Jan Andries; Stellenbosch University. Faculty of Engineering. Dept. of Civil Engineering.
    ENGLISH ABSTRACT: This study investigated a method to choose technology that reduces the rework of structural concrete works which results in poor quality during construction. The technology considered is identified as technology that can be used to improve quality control during construction. The scope of the investigation was limited to construction that consists of structural elements, such as beams, columns, slabs and concrete walls. The research questions for this study were as follows: (i) what are the causes that lead to poor construction quality of structural concrete; (ii) how can technology be used to improve the construction quality and how effective would it be and (iii) can a decision model be developed to assist a contractor to invest in such technology. The motivation pertaining to this study was based on the excessive rework costs experienced on construction projects. Rework has a disadvantageous influence on both cost and time of a project. In structural concrete projects, direct rework costs were found to be between 4-6% of the total value of concrete works. Literature showed that barriers toward obtaining good construction quality are identified as attributes of labour, management, subcontractors, and plant and equipment. The construction errors that are caused as a result of these attributes were identified and are seen as risks that could lead to rework. A questionnaire survey was used to determine the in uence of labour-, management-, subcontractors-, and plant and equipment attributes on the quality of structural concrete. Furthermore, it was also used to determine the in uence of these categories on the construction errors that were identified. Interviews were conducted to determine measures, pertaining to the identified construction errors, that could be implemented to prevent construction rework. These measures were used in the study as important processes to improve the quality control of concrete. Moreover, it was useful to establish a criteria when evaluating the effectiveness of technology to reduce construction errors. A range of technological systems, such as laser scanners, dimensioning software applications, internet protocol cameras, radio frequency identification tags, quick response codes and concrete curing sensors were evaluated for its capability and effectiveness to monitor the construction activities where construction errors potentially occur. The information gathered regarding construction barriers, -errors and technology effectiveness was used in a decision model based on risk and cost. The model advises the user whether an investment should be made to acquire technology for a project to reduce construction rework. A fictitious project with various scenarios was investigated. The model presented feasible investment decisions in cases of medium to high risk. The estimated savings for the fictitious project ranged between R 260 000 and R 1.17 million as the expected risk changed. A sensitivity analysis was conducted to determine how the model suggestion varies for different project sizes and rework expectancies. It was found that the model is very sensitive when expected rework is less than 1%. The model was validated through interviews with experts in the construction industry.