Worldwide, the medium density fiberboard (MDF) materials have been extensively used for furniture as well as a normal building material. The MDF production is based on wood materials that are obtained from the tree cutting, and this process may conduct to gradual deforestation. Different works have shown the advantages of using other renewable biomass sources for MDF manufacturing. This study aimed at assessing the potential of using the African couchgrass, as one of worldwide available grass, and which has been one of the most worrying weeds for agriculture areas. The test with the manufactured MDF checked such material properties like density, moisture content, water absorption, and thickness swelling. The established results were 727.143 kg/m3, 5.81%, 9.18%, and 7.6% respectively. All those results are in the range of standard values recommended by ASTM D1037, and they give optimism for the application of couchgrass in the manufacturing of MDF. This new material was planned to be used as a partition component. Therefore, further studies should evaluate other important properties, like fire and sound resistance, while a proposal for potential replacement of the used industrial wood glue is also welcome.
A construction contract is a mechanism to bind a project owner and a contractor in a legal agreement to construct a project against a designated monitory consideration. However, projects are usually assembled over a long period with high uncertainty and complexity. Under such a dynamic business transaction, current static contracts fail to arrange for an appropriate and stable transaction. This paper reveals, through a questionnaire survey that was sent to all grade1 and 2 contractors and all owners in Riyadh-Saudi Arabia, the most common construction contracts in Saudi Arabia and the use, causes and benefits of contract conversion. The lump sum and the unit price are the most dominant type of contracts. Owners who select the former convert them during construction to unit price contracts leading to considerable benefits to contract parties including successful project completion with negligible disputes and better relationship. Owners are advised to include a clause in the construction contract to give them the privilege, not the obligation to convert the contract from one type to another.
Crowded large space buildings are today becoming highly desirable facilities for communities, towns, and cities. Due to stricter health, safety requirements, and environmental effects, such buildings are of greater interest for research. The buildings are used for a variety of functions, including sporting, entertainment, and religious events. The Holy Mosque in Makkah Saudi Arabia is an excellent example of a crowded large space building with a maximum capacity reaching up to 2 million users, especially at the Hajj and Ramadan periods. Quite often, designer and facility managers of crowded large space buildings pay keen attention to normative and substantive (objective) safety, but research shows that perceived (subjective) safety which should also be important, is clear overlooked. To prove the significance of perceived safety, a theory has been adopted, which states that a reduction in perceived safety (PS) will negatively affect the user behaviour (UB) resulting in the occurrence of a disaster in crowded large size buildings. Initial research undertaken by the authors have identified 10 key factors affecting subjective safety in crowded large space buildings, this stage of the study is an empirical study to aimed at establishing how significant each factor affects PS and the effect of perceived safety on the UB in such types of buildings. The Holy Mosque was used as a case study. The research adopted the quantitative research methodology by collecting primary data using a group-administered questionnaire in electronic devices such as iPad from more than 1,940 Hajj pilgrims coming from 62 countries. This was analysed by SPSS and AMOS 22 for confirmatory factor analysis (CFA) and structural equation modeling (SEM) to test the interrelationships between the 10 identified factors and PS or between PS and UB through several hypotheses. The research has demonstrated that there is a significant influence on PS by most of the established factors and that PS has a significant influence on the behaviour of pilgrims in the Holy Mosque.
Learning curves in construction operations analysis is deemed as one of the main factors that determine the variation of on-site productivity and is always taken into account during the planning and estimation stage. This research attempts the assessment of learning curve models’ suitability for the effective analysis of the learning phenomenon for construction operations that are fairly complicated concerning a floating caisson fabrication process for a large-scale marine project, using productivity data. This paper investigates the role of published learning curve models (i.e. Straightline or Wright; Stanford “B”; Cubic; Piecewise or Stepwise; Exponential) by comparing their outcomes through the use of both unit and cumulative productivity data. There are two main research objectives: first, the model best fitting historical productivity data of construction activities that have been completed are investigated, while secondly, an attempt is made to determine which model better predicts future performance. The less actual construction data deviate from each model’s yielded results, the better their suitability. In the case of unit data, the cubic model fits better historical data, while in the case of future predictions, the Stanford “B” model provides better results. Respectively, the Cubic model yields better results when using cumulative data on historical data and the Straight-line model predicts in a more reliable fashion future performance Possible extensions could be developed in the area of future performance predictions, by adopting different data representation techniques (e.g. moving/exponential weighted average) or by including other (non-classic) learning curve models (e.g. DeJong, Knecht, hyperbolic models).
This paper aims to quantify the labor productivity improvement reached by the implementation of a masonry wall project design to guide field construction. A masonry wall project design is an instrument of rationalization, developed to specify the layout and steps of a masonry walls execution. The methodology is of quantitative nature and involves a practical case. The work of an enterprise in Goiânia (Brazil) was tracked by the collection of productivity data, firstly of a crew that didn’t have access to a masonry wall project design, and then of a crew that had access to the project. The evaluation of the productivity improvement was processed by means of statistical analysis, such as location and dispersion measures, average and variance, T-test, and F-value. Hypothesis tests were also performed to prove that the changes in productivity were caused by the implementation of the masonry project. The results showed that the project deployment optimized the production process in the field. There was a 26% increase in the team average productivity with access to the project design according to the hypothesis tests. The main contribution of this work is to present the beneficial impact of a masonry wall project design tailored for field construction, which allows a formal and rational approach to a heavily artisanal technique.
Delays on construction projects constitute a major source of concern due to its associated cost increases and loss of revenue. The Gulf Cooperation Council (GCC), of which Oman is a member, faces huge delays on their projects. Such delays in the GCC were among factors fingered in the collapse of the UK’s Carillion. Despite cultural similarities, substantial variability exists within the GCC construction sector which requires country-specific studies. The quest to understand delay causes results from the need to curtail wastes and adjust to the new regime of low commodity prices. There is a dearth of studies specific to the governorate of Muscat exploring the causes of delays and this study seeks to fill that gap. A structured survey questionnaire was administered at two independent events organized by the RICS and ICE in Muscat. The top causes of delays ranked using the Relative Importance Index (RII) include variation and changes in design, Poor site management and supervision, ineffective planning and scheduling, unclear and inadequate details in drawing, poor qualification of the contractors and technical staff, delay in material delivery, and shortage of labor. Contractors were found to be most likely to cause delays among the 6 categories of sources.
The strategic role of indigenous construction firms (ICFs) in the development of the construction industry better construction output and infrastructural development in developing countries cannot be overemphasized. These goals may not be achieved if firms’ psychosocial construction work environment and wellbeing (PCEW) are not appraised. To this end, this study identified and assessed factors relating to PCEW in the 37 factors influencing the viability and performance of construction firms obtained from the extant literature. A sample size of 65 staff of 31 ICFs out of a total survey of 177 staff of 59 ICFs that were awarded building contracts in selected institutions in Nigeria was accessed for this study. Respondents rated each factor on a five-point Likert scale of importance and mean scores were used to rank the factors after identifying factors that are related to ICFs’ PCEW. The study identifies 14 PCEW related factors out of the 37 factors influencing the viability of ICFs and six of the top ten very important factors influencing ICFs’ viability having high factor loading are PCEW related. The factors are quality of construction work and services, availability of skilled labour, employee satisfaction, and availability of artisans and craftsmen. Steady emphasis on factors influencing PCEW of construction workers amidst various factors influencing ICFs’ viability is necessary for a healthier construction work environment and wellbeing.
The article presents sources of production knowledge and thoroughly describes its identification which on the construction of decision trees, and on the construction of knowledge bases for production processes. The problems that arise during the technical preparation of production are briefly characterized and the advanced algorithm with which decision trees can be built is described in detail. A decision tree was built based on real data from the manufacturing company. Decision trees are presented as a method of knowledge representation.
Internal logistics is a key element of a production process as it specifies product quality, timeliness and value of orders. The purpose of the research was to determine the amount of non-compliance in the selected production process caused by internal logistics operations. The analysis covers both the quantity and type of non-compliance as well as the cost of non-compliance. One of the basic quality management tools was used in the research - Parteo-Lorenz analysis. An attempt was made to identify potential causes of non-compliance. The significant impact of non-compliance arising in internal logistics operations in production costs was pointed out.
Bisphenol A (BPA) is an industrial chemical used as an additive in conventional point-of-sale thermal paper receipts, in the production of many polycarbonate plastics, and epoxy resins lignin for food. BPA is xenoestrogen, a foreign compound that is not naturally produced in living organisms, but which acts similarly to natural 17-ß estradiol (natural estrogen). Due to its weak estrogenic activities, BPA exposure may influence multiple endocrine-related pathway, and is associated with prostate and breast cancer, neurobehavioral deficits, heart disease, and obesity. Furthermore, BPA may act as a DNA methylation agent and cause altered gene expression in the brain. Human exposure to bisphenol A is a matter of controversy. This review shows a potential risks in workplace resulting from contact with bisphenol A. The work presents the contribution of BPA exposure levels via dermal contact and the relationship between BPA exposure level and oxidative DNA damage.