A decision model for the investment in technology to reduce concrete rework

Podges, Tian Martin (2017-12)

Thesis (MEng)--Stellenbosch University, 2017.

Thesis

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.

AFRIKAANSE OPSOMMING: In hierdie studie is 'n metode ondersoek om konstruksieherwerk met behulp van tegnologie te verminder. Die tipes konstruksie waarop gefokus word sluit beton strukturele elemente soos balke, kolomme, blaaie en mure in. Die ondersoekende vrae in die studie is soos volg: (i) Wat is die oorsake van slegte konstruksiekwaliteit? (ii) Hoe kan tegnologie gebruik word om konstruksie kwaliteit te verbeter en hoe effektief sal dit wees? (iii) Kan 'n besluitnemingsmodel om 'n kontrakteur te help met die aankoop van sulke tegnologie ontwikkel word. Die motivering van die studie word deur die hoë herwerkkostes in die konstruksie-industrie gedryf. Herwerk het nagevolge met betrekking tot die tyd en koste van 'n projek. In Suid-Afrika word herwerkwaardes van tussen 4-6% op die totale waarde van beton werk op 'n projek ondervind. In die navorsingsbronne word herwerk aan eienskappe van arbeid, bestuur, subkontrakteurs, en aanleg en toerusting toegeskryf. 'n Vraelysopname is gebruik om die invloed van arbeid, bestuur, subkontrakteurs, en aanleg en toerusting op die kwaliteit van konstruksie te bepaal. Dit is ook gebruik om die invloed van hierdie kategorieë op konstruksiefoute te bepaal. Onderhoude is met kenners in die industrie gevoer om vas te stel watter maatreëls gebruik kan word om konstruksiefoute te verminder. Die maatreëls is gebruik in die vestiging van 'n kriteria waaraan tegnologie moet voldoen om vir kwaliteit verbetering gebruik te word. Die volgende tipes tegnologie is oorweeg vir die studie: laserskandeerders, afmeting-sagteware, radio-frekwensie-identifiseringstoestelle, vinnige reaksiekodes en betonsensors. Die inligting rakende konstruksiehindernisse, foute, voorsorg maatreëls en tegnologie effektiwiteit is in die ontwikkeling van 'n besluitnemingsmodel gebruik. Die model is gerig op risiko en koste: Op grond daarvan word 'n kontrakteur geadviseer of die belegging in tegnologie tot koste besparing kan lei. 'n Fiktiewe projek met verskeie senarios word gesimuleer om die gebruik van die model te demonstreer. Deur die simulasies word beraamde besparings tussen R 260 000 en R 1.17 miljoen deur die model voorspel. 'n Sensitiwiteitsanalise is ook gedoen om te wys hoe die beraamde koste besparing wissel vir verskeie projekwaardes en herwerkverwagtinge. Die mening van kenners in die industrie is tydens onderhoude ingewin. Hulle het hul goedkeuring gegee.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/102851
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