Thesis (MScEng)--Stellenbosch University, 2011. / ENGLISH ABSTRACT: Hybrid concrete construction (HCC) is a construction technique that makes use of both in-situ and pre-fabricated concrete products by making optimum use of the advantages of both these methods in the same project. Although the advantages of this building method is well recognised throughout the world and a feasibility study illustrated that HCC is a suitable building method in South Africa, it remains under-utilised in the country. HCC encourages early involvement from the project team and provides clients with the best value projects and a "win-win" situation for the project team during the project development. The objective of this study is to identify barriers that prohibit an increased utilisation of HCC for the South African construction industry. Additionally, it provides possible solutions to overcome these barriers. These proposed solutions are similar to the programmes and methods that are implemented in other countries to improve their HCC utilisation. Furthermore, drivers are identified in this study to implement these solutions in the industry and a proposed "change model" is developed for private companies to assist with the change process. This study is unique because current South African conditions are used to establish the barriers and solutions. Furthermore, it takes into account that not all countries have such progressive construction industries as the European markets and therefore it considers solutions and drivers that are suitable for less advanced industries such as South Africa. The model that is proposed is applicable to any industry regardless of its nature or country. Although the United Kingdom is not the widest user of pre-fabricated concrete products, their HCC research is extensive, making it a suitable comparative country for the South African construction industry. During the investigation, the procurement methods in South Africa were found to be traditional and do not allow for early involvement or partnering in the project team. To obtain early involvement, it is critical to initiate methods such as design-and-build, contract management or public-private-partnerships during the procurement phase. Decision and design assistance from the whole project team and software tools are essential when HCC is considered. Because the South African construction industry does not provide such support it is advised here to incorporate contractors from an early stage and to develop software tools that can assist during the decision making and design process of HCC structures. The industry does not provide the project team with sufficient training programmes that increase knowledge of HCC. Training programmes that are cognitive stimulating must be developed for the industry. Furthermore, a database is required to illustrate the utilisation of different pre-fabricated products and in different projects within South Africa. Labour-intensive construction regulations and green building techniques (not compulsory) are promoted in South Africa. Labour-intensive programmes should consider the negative impact it has on the labourers and consider HCC as a building technique because the pre-fabricated elements are manufactured in a controlled and safe environment. It is advised that the toolkits that are used for green building accreditation, must be revised to accommodate the additional benefits such as less waste generation, that HCC offers to a project. Regardless of the country in which HCC is utilised, the environment must be acceptable for the innovation. By analysing the criteria that influences the use of HCC in a country and adding weighting functions to these criteria, the acceptability towards the innovation can be obtained. Furthermore, public clients and companies are recognised here as drivers of change. While public clients can commit to HCC for the cost, labour-intensive factories, green building methods, improved health and safety, training for labourers, private companies can utilise HCC to provide best value to a project. A model is proposed here for innovative companies that will allow them to change not only the company, but the industry towards a HCC "mindset". / AFRIKAANSE OPSOMMING: Hibriede beton konstruksie (HBK) is ’n tegniek waarby beide voorafvervaardigde betonelemente en in-situ beton in dieselfde projek gebruik word ten einde voordeel uit beide metodes te trek. Alhoewel die voordele van die konstruksietegniek wel bekend is in talle lande van die wêreld en ’n uitvoerbaarheidsanalise getoon het dat HBK ’n voordelige konstruksiemetode vir Suid-Afrika is, is dit tans onderbenut in die plaaslike sektor. HBK bied vir kliënte projekte van goeie waarde en omdat dit vroeë betrokkenheid verg vanaf die projekspan, resulteer dit ’n "wen-wen" situasie tydens die projekontwikkeling. Die doel van hierdie studie is om die hindernisse te ondersoek wat veroorsaak dat HBK nie meer gereeld in Suid-Afrika gebruik word nie. Ten einde die effekte hiervan te verminder, word moontlike oplossings vir hierdie hindernisse voorgestel. Die oplossings is gebaseer op tegnieke en metodes wat geïmplimenteer word in ander lande waar HBK gebruik word. Rolspelers wat hierdie verandering na HBK kan dryf word geïdentifiseer en ’n model om verandering binne ’n maatskappy te lei word voorgestel om die rolspelers te ondersteun tydens die proses. Hierdie studie is uniek omdat dit inligting gebruik van die huidige situasie van die Suid-Afrikaanse konstruksie-industrie om die hindernisse en oplossings te identifiseer. Omdat nie alle konstruksie-industrieë so vooruitstrewend is soos in Europese lande nie, is die oplossings en rolspelers relevant vir enige land wat ’n industrie het wat soortgelyk is aan Suid-Afrika. Die model wat voorgestel word is ook relevant tot enige industrie afgesien van die land waar nuwe tegnieke geïmplimenteer word. Alhoewel dit bevind is dat die Verenigde Koningkryk nie die grootste gebruikers van HBK is nie, is hulle navorsing in die veld omvattend. Daarom word die Verenigde Koningkryk beskou as ’n voorbeeld om Suid-Afrika se konstruksie-industrie mee te vergelyk, asook om inligting van HBK te verkry. Tydens die studie is bevind dat die projekaanstellingsmetodes van projekte in Suid-Afrika tradisioneel is, aangesien dit nie toelaat vir vroeë betrokkenheid of vennootskappe binne die projekspan nie. Om vroeë betrokkenheid te verkry, is dit noodsaaklik om van ontwerp-en-bou, kontrakbestuur of publiek-privaat-vernootskappe gebruik te maak. Tans is daar geen hulp wat aan ontwerpers verleen word ten opsigte van besluitnemingsmodelle en ontwerpsagteware wanneer HBK oorweeg word in Suid-Afrika nie. Die behoefte aan sulke bystand dui daarop dat sagtewarepakkette ontwerp moet word wat toepaslik is vir Suid-Afrika se konstruksie-industrie. Die industrie bied nie doelgerigte en genoegsame opleidingsprogramme aan om die industrie se kennis van HBK te verbreed nie. Addisionele opleiding wat kognitiewe stimulasie sal bied vir die hele projekspan word aanbeveel. ’n Databasis wat HBK projekte insluit, moet geskep word om die industrie bloot te stel aan die verskillende moonlikhede. Arbeid-intensiewe konstruksie-regulasies asook groen konstruksietegnieke (nie wetgedrewe nie) word sterk bevorder in Suid-Afrika. Dit word hier aanbeveel, dat voorafvervaardiging se addisionele voordele in ag geneem word wanneer hierdie regulasies en tegnieke relevant is. Hierdie voordele sluit onder meer in: die veiligheid wat aan werkers gebied word in arbeid-intensiewe fabrieke en die vermindering van afval in HBK projekte. Afgesien van die land waarin HBK gebruik word, moet die omgewing ontvanklik vir die tegniek wees. Deur verskillende kriteria te analiseer wat die gebruik van HBK beïnvloed binne ’n land en geweegde faktore daaraan te koppel, kan die ontvanklikheid van die innovasie bepaal word. Laastens word publieke kliënte en maatskappye as die drywers (of katalisators) wat verandering kan meebring, beskou. HKB bied onder andere die volgende voordele aan publieke kliënte: koste-effektiwiteit, arbeid-intensiewe werk, groen konstruksie, beter gesondheid, veiligheid en opleiding vir werkers. Maatskappye kan gebruik maak van HBK om waarde tot hul projekte toe te voeg. ’n Model word hier voorgestel om innoverende maatskappye in staat te stel om nie net hulself nie, maar ook die industrie as ’n geheel te help om ’n gesindheidsverandering jeens HBK te skep.

The focus of this thesis is on the precast concrete products manufacturing industry, which as one of the labour-intensive industries requires a substantial number of highly skilled operators in terms of crews to produce the final product. A crew is a group of multi-skilled chargehands and operators that have various skills and experience necessary to conduct an activity in a professional way. The high cost of skilled operators and the apparent inefficiencies of utilising such skilled operators in the industry are the major driving force. To achieve this, optimal crew allocation is required. Crew allocation is complex because of the multi-criteria nature of the problem and availability of thousands of possibilities and allocation alternatives. There is a gap in previous research efforts associated with crew allocation planning in the precast industry. Current practices suggest that the crew allocation process is carried out intuitively and the allocation of crews to production processes is subjective. This has led to high process-waiting times, improper allocation of skilled operators and ultimately higher production costs. In this context, the aim of this research is to propose an effective crew allocation methodology and a computer-based intelligent simulation model for its implementation. The objective of the approach is to guarantee a better workflow through minimising process-waiting time, optimising operator utilisation, and subsequently reducing the allocation cost. This research develops a holistic and integrated methodology for modelling crew allocation problems by reviewing state-of-art resource allocation techniques, structured interviews with production managers, site visits and a detailed case study. The methodology is developed using an IDEF0 process model and a generic process map for both the business and the production processes of the precast manufacturing system. A multi-layered genetic algorithm model is developed in conjunction with a process-simulation model to form a hybrid allocation system dubbed ‘SIM_Crew’. The model incorporates databases (Excel and MS Access), a simulation model (developed using Arena 12.0) and genetic algorithms (developed using Visual Basic for Applications) to facilitate the generation and evaluation of various “what-if” crew allocation scenarios. A number of performance criteria have been developed to evaluate the allocation plans. ‘SIM_Crew’ enables the investigation and analysis of allocating possible schedules and provides a facility to visualise the production processes. ‘SIM_Crew’ was validated using real life case study data and it was concluded that the allocation of crews to precast processes using genetic algorithm improves the throughput time and reduces the allocation cost as compared with real life production data. It is anticipated that future use of this research will solve the crew allocation problem in the precast industry.

This thesis outlines the early developmental history of concrete block in America with special attention being placed on the years leading up to the St. Louis Louisiana Purchase Exposition of 1904. In general, the history of concrete block in contemporary building material histories begins with the innovations in block machinery that took place at the turn of the 20th century. However, the history of concrete block begins much earlier than these innovations. Harmon S. Palmer invented the first commercially successful concrete block machine in 1900, but there were many reasons why concrete block became widely used during the first half of the 20th century. The establishments of a domestic Portland cement industry, the innovations in concrete block machinery, and the marketing and promotion of concrete and concrete block at the 1904 St. Louis Louisiana Purchase Exposition, are all major reasons why concrete block began to be widely used in America. / Concrete : primer -- Concrete : a brief history -- Concrete block : an early history -- Portland cement -- The commercialization of concrete block -- Concrete block on the world stage : the 1904 Louisiana Purchase Exposition. / Department of Architecture

D. Tech. (Department of Marketing Management, Faculty of Management Sciences), Vaal University of Technology. / In recent years, the concept of relationship-marketing earned eminence in academia with associated implications for marketing strategy. The aim of this study was to examine relationship intentions in the business-to-business (B2B) context from the concrete product environment within the construction industry of South Africa. Literature reviewed reveals that empirical studies for concrete product environment and the construction industry is limited, principally in South Africa, concerning the dimensions of relationship intentions. As deliberations on relationship-marketing intentions carry on maturing, there are imperative concerns yet to be clarified, one of which relates to customer’s buying behaviour in relation to the dimensions and outcomes of relationship intentions. Given the increasing prominence of customer buying patterns in modern marketplaces, the study intends to empirically analyse the dimesions and outcomes of buyer-seller relationship intentions, with reference to the civil and building concrete product users in a B2B setting within the South African construction industry. The civil and building engineering contractor segments were selected as research sites owing to their scope and size, which signify a productive market segment with prospects of influencing future behavioural intentions in the construction environment. The the study was underpinned by the relationship-marketing theory and social exchange theory, which clarified the dimensions and outcomes of relationship intentions of the civil and building constructs that underlie concrete products. As the study intended to determine the dimensions and outcomes of relationship intentions of civil and building contractors (customer) towards their concrete product manufacturer (supplier) organisations, a descriptive research method was chosen. The objective being to confirm and expand the dimensions of buyer-seller relationship intentions in the B2B industry context and to examine the explanatory power of the indetified dimensions. The current study employed a quantitative research method that is entrenched in the post-positivist paradigm, which also underpins this study. Data were collected using probability sampling in the form of systematic random sampling. A sample size of 560 respondents returned fully completed questionnaires. As the study was descriptive in nature, the reliability and validity of data were analysed, correlation analysis and structural equation modelling (SEM) were performed. The exploratory and confirmatory factor analysis were also conducted to confirm and expand the factor structure of the relationship intention dimensions. Preceding the main study’s data collection process, a pilot survey was undertaken to examine the correctness and accuracy of the questionnaire. The data collected were examined with the use of Statistical Package for the Social Sciences (SPSS) 25.0 and Analysis of Moment Structures (AMOS) version 25.0. The preliminary data analysis included the procedure of coding and examining the distribution of scores. In addition, the normality test results revealed that data were normally distributed. To confirm the consistency of the measuring instrument and its items, the reliability and validity tests were carried out. The results of the consistency of measures demonstrated that the measuring instrument was reliable. The correlation analysis disclosed a weak relationship between expectations, involvement and feedback towards relationship quality, whereas a moderate association was revealed between forgiveness and trust towards relationship quality, while a strong association was discovered between fear of relationship loss, information sharing and flexibility towards relationship quality construct. The suitability of the measurement and structural models were evaluated prior to testing the hypothesised relationships. The suggested relationships were verified by structural equation modelling (SEM). The hypotheses testing findings revealed that concrete product repurchase intentions by the study respondents were significantly and positively motivated by the supplier’s relationship quality and commitment that leads to customer satisfaction, loyalty and repurchase intentions. A framework of relationship marketing intentions for the concrete product environment of the South African construction industry was developed. It was anticipated that the proposed framework will contribute towards addressing the insufficiencies in the application of relationship marketing strategies. The empirical study results advocated that concrete product manufacturer-suppliers (CPM) must invest in methods of increasing their levels of relationship quality and commitment to maintain customer satisfaction and loyalty, which will lead to customer repurchase intentions. The study results revealed that unlike previous relationship intention studies that found five dimensions, this study proposed and found eight (involvement, expectations, forgiveness, feedback, fear of relationship loss, trust, flexibility and information sharing/exchange) dimensions of relationship intentions within the B2B concrete product environment. Furthermore, the study results revealed that customer satisfaction can be upheld by concentrating on relationship building strategies, which fuel customer loyalty and repurchase intentions by meeting or exceeding customer needs and requirements. One of the study contributions is the investigation of the order of the dimesions of relationship intentions in a B2B context for the concrete product environment within the construction industry. Therefore, the study pens down both the theoretical and practical contributions to the relationship marketing literature. Paths for additional research is offered. The outcome of this study advanced a framework of the dimensions of relationship intentions, which may possibly benefit future researchers. Future studies must consider the application of a cohesive research model, which includes supplementary variables using a larger sample size utilising a longitudinal study with the purpose of increasing generalisability of the results.

This diploma thesis is focused on the description and summary of existing knowledge about vibro-pressed concrete products with treated surface with protective coating, that is hardering by ultravioled and infrared radiation. The theoretical part describes the production of vibro-presses products, possible wayt of finishing the surface including the description of the most commonly used materials and the methods of application and hardering of protrctive coating on the surface. Another point of the theoretical part is creating of lime efflorescence on the concrete surface and their subsequent disappearance. The experimental part of the thesis is ficused on obtaining information about the properties of the modified pavements by these techologies and comparing the acquired properties with the charakteristice of the reference pavements that do not have any protective coating on their surface.

This thesis deals with the application of Markov chains for the production of concrete products. The theoretical part is focused on clarifying the concepts of risk management and describes the procedures for dealing with classical Markov chains. There are presented basics of fuzzy logic and finally there is explained the procedure using fuzzy logic in calculating of classical Markov chains in the subsection entitled Fuzzy Markov chains. The practical part describes production process, namely concrete pavements. On this production process is applied knowledge from the theoretical part and there is a comparison and evaluation of two methods of Marcov chains calculation (classic and fuzzy approach).

This diploma thesis is focused on studying the influence of different types of surface treatments on vibropressed product. The main goal is to characterize surface treatments consisting of application of surface coatings that are hardened by infrared or ultraviolet radiation. Theoretical part gives specifications already known methods for surface finishing. Briefly describes selected types of prefabricated concrete parts and specificate the requirements for these products. It also describes used test methods. The experimental part was aimed at establishing the effectiveness of changing properties concrete products by adding coatings on their surface. This was achieved by testing the properties of concrete paving blocks with modified surfaces and testing of reference blocks that did not have any surface treatment followed by mutual comparison of the results.