Choosing the Right Building Method for Parking Garages under Apartments: An AHP-Based Evaluation with a Lean Construction Perspective

This thesis is written in collaboration with Total Betong AS, a turnkey contractor in Norway, who has a vision to build better underground parking spaces under apartment buildings at a lower cost. It is also a governmental goal as the need for parking spaces under new apartment buildings is constantly increasing and the value of a parking space is quite significant ranging from NOK 200 000 - NOK 700 000 (Marschhäuser, 2020). The challenge at hand is to obtain an additional parking space by selecting a building method that ensures efficient space utilization while adhering to schedule and budget constraints. There are several construction methods when building a concrete structure, but in this study, we focus on cast-in-place concrete, prefabricated concrete, and a combination of both. Castin-place concrete involves creating formwork shapes with reinforcement and subsequently filling them with fresh concrete on-site. On the other hand, prefabricated concrete refers to elements produced in a factory under controlled conditions. These elements are then transported to the construction site for Just-in-Time delivery and installation. In addition to the quantitative factors of time and cost, there are various qualitative factors that influence the choice of building method. Hence, it has been useful to use an analysis method that combines both qualitative and quantitative factors. The Analytic Hierarchy Process (AHP) is a multicriteria decision-making process that attempts to select a building method based on input from experienced stakeholders with relevant knowledge of such projects. Questionnaires were sent to experts to select critical factors for the choice of building method, and further assign them a degree of importance in relation to each other. This way, we also get an objective answer based on subjective opinions. Research shows that productivity levels are lower in the construction industry than in other industries, while costs and conflict levels are increasing. For these reasons, interest in Lean techniques and tools has increased to promote collaboration, communication, creativity, and risk reduction. This thesis therefore explores how these techniques can identify dependencies throughout a construction project. Lean tools such as the Last Planner System (LPS) and Pull-Planning techniques are effective when discussing criteria that determine the choice of execution methods. This can reveal that some factors are more important than others, which can immediately rule out a building method. 4 The study primarily employs qualitative research methods, including an extensive literature review and a case study involving three reference projects. Two of the reference projects have been completed, while the third project is ongoing and has been utilized for the AHP analysis. The case study incorporates various data sources, such as project documents, tenders, semi-structured interviews, and site visits, to gather comprehensive information. From the AHP analysis, it emerges that prefabricated concrete is the preferred choice of the design team for the latest reference project, Bykronen. HSE, quality, and operational flexibility dominate the choice of construction method compared to the usual factors such as cost and time. From the interviews and case studies, it emerges that column-free spans and large wall and roof elements are desirable as they allow for more parking spaces and better parking utilization. It is therefore concluded that parking basements are particularly well suited for construction with prefabricated elements as it has a great potential for improvements in all construction phases while reducing the indirect costs that can be significant in traditional construction with casting. Every decision should be grounded on project-specific considerations; however, valuable insights and lessons can often be transferred from one project to another

Effektivisering av produksjon av bitumenperler med resirkulert plastikk

Denne forsøksbaserte oppgaven består av to deler. Den første delen handler om å effektivisere produksjonen for bitumenperler. For å effektivisere produksjonen vil det bli laget en fabrikk som består av flere maskiner og elementer. Gjennom denne fabrikken vil det være mulig å produsere bitumenperler i større mengder og forenkle arbeidet. Den andre delen omhandler å optimalisere bitumenperler ved å erstatte steinmateriale med resirkulert plastikk. Dette blir gjort ved å utføre ulike tester som å måle størrelsen, densitetstest og heftprøve. Deretter vil det sammenlignes opp mot steinmateriale som er det vanligste materiale når det kommer til bitumenperler. Til slutt vil det bli laget bitumenperler med steinmateriale og plastikkpellets gjennom fabrikken og sammenlignes med hverandre. Hittil er det ikke blitt skrevet en oppgave med å optimalisere bitumenperler med resirkulert plastikk. Dermed var det ingen andre oppgaver dette kunne sammenlignes med. Venting på bestillinger, verksted og restriksjoner knyttet til bruk av lab grunnet Covid-19, førte til knapphet med tid. Dette påvirket planleggingen og utførelsen av produksjonen som ble utsatt gjentatte ganger av uforventede hindringer. Sluttproduktet har et enormt stort potensial for å dominere markedet innen fuging og vei i fremtiden. For dette må det gjøres enda mer forskning og testing. Med bedre utstyr, og utstyr mer egnet for produksjon av bitumen ville sluttproduktet vært mer positivt enn det faktiske utfallet.This experimental task consists of two parts. The first part is about the efficiency of the production of bitumen beads. To streamline production, a factory will be created consisting of several machines and elements. Through this factory, it will be possible to produce bitumen beads in larger quantities and simplify the work. The second part deals with optimizing bitumen beads by replacing stone material with recycled plastic. This is done by performing various tests such as measuring the size, density test, and adhesion test. Then it will be compared to stone material which is the most common material when it comes to bitumen beads. Finally, bitumen beads with stone material and plastic pellets will be made throughout the factory and compared with each other. To date, no task has been written to optimize bitumen beads with recycled plastic. Thus, there were no other tasks this could be compared to. Waiting for orders, workshops, and restrictions related to the use of the lab due to Covid-19, led to a shortage of time. This affected the planning and execution of the production, which was repeatedly subjected to unexpected obstacles. The end product has an enormous potential to dominate the market in grouting and roads in the future. For this, even more research and testing must be done. With better equipment, and equipment more suitable for the production of bitumen, the end product would be more positive than the actual outcome