Table 5 - uploaded by Tarek Zayed
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The 95% confidence interval (lower, average, and upper limits) for effective and extra expenses.
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Assessing productivity, cost, and delays are essential to manage any construction operation, particularly the concrete batch plant (CBP) operation. This paper focuses on assessing the above-mentioned items for the CBP using stochastic mathematical models. It aims at (i) identifying the potential sources of delay in the CBP operation; (ii) assessing...
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... The following Fig.1 shows a different RMC Plant Management related aspects. Tarek Zayed et al. (2006) studied that major cause of delay which affects the RMC Plant system and Classified Uncontrolled delay and Controlled delay. The uncontrolled delay because of factors that are out of concrete batching Plant management. ...
... . Shown below is about various delay factors with occurrence probability.[20] Fig. 3 Probability of Various Concrete Batching Plant Delay ...
... While various approaches to the analysis of different techniques had been developed, a clear analysis of this chronic issue of time performance of construction projects is still hard to find. Although many studies have published causes and factors affecting schedule and cost performance using numerous techniques [1,2,3] most of these studies failed to examine how the identified causes work together to influence schedule performance in projects, few studies that try to explain how the relationship between the cause of the delay affect each other and how this can affect the project schedule. With the stated situation in the Surabaya construction sector, quantification of the relationships among different causes of delay in Surabaya construction projects is certainly an important topic for investigation. ...
... (2) External causes included industry nature, construction client knowledge, weather, and economic level which they are representing firm's management control. Zayed and Nosair [27] proposed batch plant production optimization model for maximizing net profit using a linear programming technique. A transmixer are most important effective production tools for ready mixed concrete plant and its capacities are 4, 6, 8 and 12 m 3 . ...
... Technology use is most important role for quality of ready mixed concrete production Vikan [23]. Zayed and Nosair [27] focused on measuring concrete batch plant cost and productivity using Artificial Neural Network (ANN) technique. Zayed and Nosair [27] developed some models to get delays effect on unit cost in batch plant by applying stochastic mathematical technique. ...
... Zayed and Nosair [27] focused on measuring concrete batch plant cost and productivity using Artificial Neural Network (ANN) technique. Zayed and Nosair [27] developed some models to get delays effect on unit cost in batch plant by applying stochastic mathematical technique. Yan and Lai [24] evaluate and improving production process in a concrete batching plant using management tools. ...
It is clear that most of mega and medium sized projects in Egypt are using ready-mix
concrete in their construction work. It is important to improve the actual production rates of batch plant to optimize the usage of their outputs; the use of concrete batch plants by concrete mixers is rapidly increasing in the construction industry. This is an important step in securing high productivity in the industry. Concrete batch plant specialists are well aware of the importance of productivity, and hence, there is a great potential for productivity improvement in batch plant concrete industry, Batch plant of concrete is very essential part in construction process, which is defined as central plant on project site and is transported by transit mixers to projects, this paper attempts to classify, investigate, and sort causes that affect batch plant productivity. To perform that goal, researchers invited experts on this field by answering detailed a questionnaire survey. It was taken brain storming into consideration, through more effective causes was identified in batch plant. Totally, forty five (45) related causes are classified into five (5) major groups. This survey was done with representatives and experts from public and private automated batch plants. All data was analyzed by Analytic Hierarchy Process (AHP), ranking and simple percentages. All ranked causes were demonstrated and mentioned against their most effective causes to the batch plant productivity Egypt are facing many problems which affect ready mix concrete quality and productivity.
... The major objective of this study was to focus on predicting and improving concrete batch plants' performance ratio by: (1) Classifying the concrete batch plants; (2) Using large scale of detailed data which is collected from different and more concrete batch plants, and this will be done through studying them during start of 2012 till the end of 2016; (3) Using collected field data to recognize variables affecting concrete batch plants' performance ratio to propose a general and simplified models for predicting actual performance ratio at any concrete batch plant as function with all variables; (4) Improving concrete batch plants' performance ratio by optimizing most effective variables that affect the concrete batch plants' performance ratio; (5) Using the Statistics Package for Social Science (SPSS) software; then develop a general model in its final form; (6) Obtaining stepwise forms of general model using SPSS to simplify and reduce the lowest and negligible effective variables in proposed general model and estimating alternatives for simplified formulas, by using these proposed models any manager can forecast the behavior of concrete batch plant and its performance ratio for any new construction site orders after knowing the values of all variables; (7) Evaluating the correlation matrix for censoring the impact on concrete batch plants' performance ratio by variable changes for proposed models; (8) Applying the general and simplified models using a real case study on Suez power station project which use ready mixed concrete with theoretical capacity equal to 160 m 3 /h. The case study will be conducted to validate and verify the applications of the proposed general and simplified models to give optimum expressway for ready mixed concrete construction projects; and (9) Listing the conclusion, recommendations and suggested future studies. ...
... System definition is a set of interacting components or elements that act together to acquire a common goal. Zayed and Nosair [5] explained a model purpose which determines how more changes in numerous components of the system model might affect other system elements. It was aided for designing, learning, predicting, and comparing options harmlessly and cheaply [6]. ...
... F is the dispersion measure around mean, which is presented in Eq. (5). The variance is measured in units that are the square of those of the variable itself. ...
Producers of ready mixed concrete think of improving concrete batch plants’ performance ratio to provide the construction market with high quality standards, save cost and time. Ready mixed concrete (RMC) is a mixture of different materials, which is delivered to customer in unhardened state and freshly mixed. Major objective of this study was to provide a clear understanding for predicting and improving the concrete batch plants’ performance ratio by use analysis of large collected data from more and different concrete batch plants and determining the most effective factors that have a great effect on concrete batch plants’ performance ratio. Predicting the actual future performance ratio and production rates for any concrete batch plant according to a groups of effective factors is the essential sector which is suggested in this paper using smart modeling analysis. Improving the performance ratio of concrete batch plant is selected because of its importance in construction field by studying and analyzing the most effective factors. The study will be done by collecting and studying large detailed data through start of 2012 till the end of 2016 and it will illustrate the time, quantities, distances and factors which affect concrete batch plants’ performance ratio. This paper is divided into six main groups, which are illustrated as follows: (1) It concludes the historical information about concrete batch plants and RMC, and introduces the objective of this paper and the most convincing definitions for productivity and Performance Ratio (PR). (2) It explains general information for ready mixed concrete batch plants, classifies plant types for determining criteria of pumping method and declares the modeling techniques, concept of standard performance, measuring productivity difficulties, productivity cycles, factors affecting equipment productivity, applications of construction productivity, concrete placement process, concrete equipment selection and methods of construction. Factors affecting concrete batch plants’ performance ratio were mentioned and it discussed the related studies for problem statement. (3) It mentions the concrete batch plant classifications, advantages and disadvantages of ready mix concrete batch plants, mixing process and the methodology. It analyzes and improves the concrete batch plant performance ratio using optimizing of its most effective variables. (4) It introduces and analyzes all variables data at the same time using input phase by Statistics Package for Social Science (SPSS) software; then the estimated model was developed in the final form. Stepwise forms of the model were done using SPSS to reduce and simplify the proposed model for getting the alternative simplified formulas and neglect the variables that have lowest and negligible effect. On the other hand, correlation matrix was done to indicate what will be impacted on concrete batch plant performance ratio when each variable changes. (5) It introduces an application of general and simplified models for a real case study on Suez power station project, which uses ready mixed concrete with theoretical capacity equal to 160m³/h. The case study will be conducted to validate and verify the applications of the proposed general and simplified models to give optimum expressway for ready mixed concrete construction projects. (6) It introduces conclusions, recommendations and suggests future studies.
... A number of past research have found major reasons for delay example [2]. Others have used advanced techniques such as fuzzy logic [3] to measure reasons for delay and adapt activities and project durations; or have measured the effect of delay of specific delayed events like [4] who used mathematical models to evaluate the impact of delay on the cost of a concrete batch plant. Although these researchers have investigated the major causes of delays, they did not look into the effects when different factors combine to cause schedule delays. ...
Transportation infrastructure, specifically road projects, is the backbone of economic and social development of many countries. Successful road infrastructure projects are delivered with reduced cost, on time. Factors contributing to Construction delay in road construction projects in Libya were identified and ranked through a questionnaire survey distributed to owners, consultants, and contractors involved in road projects. A total of 256 completed questionnaire forms were received and analysed. A Structural Equation Modelling SEM Path Model of relationship between delay factors and effects in road construction was formulated and evaluated using [SEM] 21 software. 49 factors classified into eight groups of factors and three groups of effects of delay. The contractor group in delay factors had the greatest impact on road construction delay with path coefficient β-values of 0.249, while financial groups in delay effects had the greatest impact on road construction delay with path coefficient β-values of 0.88. The R2 value of the model is 0.48, indicating that the developed model substantially explains Construction delay. This rigorous multivariate analysis has identified several causative factors that contribute to delay in road construction projects in Libya. The findings will help all parties involved in construction projects to achieve better control over construction delays, and will provide support for practitioners to incorporate risk analysis for potential Construction delay in future projects. As well as for researchers in the field of road construction and understanding of the factors causing project cost overruns in developing countries.
... Another related study managed cost in RMC plants with mathematical random models. This research referred to the effect of delay on concrete unit cost [15]. Another researches studied new approaches in modeling and also quality control of batching plants based on automation system [16,17]. ...
In almost all countries, a major percentage of the manufactured cement and aggregates is used in Ready-Mixed Concrete (RMC) plants. Therefore a material inventory control system is needed to form a consumption pattern for this material to optimize warehousing cost and ordering in RMC plants. Such a material inventory control system of batching plants could be applied as an approach for optimal estimation of the tanks required for storage and feeding of material. In this research, a material inventory control system of batching plants has been developed by Fuzzy Logic (FL) with Economic Order Quantity (EOQ) model of inventory control. The optimal order quantity of raw materials in batching plant can be predicted with fuzzy logic.
... Concrete can be mixed in a batch plant offsite or Onsite (OBP). While OBP is installed inside a specific project to deliver concrete only to that project, Ready Mixed Concrete (RMC) is used to sell concrete to different projects (Zayed 2006). ...
... In addition, in the same study, a model was designed to determine the optimal number of transit mixers based upon the required quantity of concrete. Zayed (2006) focused on the management of the cost of ready-mixed concrete production centers using a stochastic mathematical model. Calis G. and Yuksel O. A. (2010) studied the layout planning optimization of construction facilities by using ant colony algorithms. ...
The Iranian construction industry confronts a remarkable increase in concrete consumption. Practitioners believe that conventional on-site construction methods cannot be used widely - especially in large cities - because of the environmental, technical, and economic considerations. These days, central mix plants or batching plants are widely used in ready mixed concrete production plants. However, these plants are criticized for low productivity, poor safety records, and high amount of land space used. The overall concrete production process can be improved by means of a layout optimization effort. An effective layout plan can directly improve the efficiency of the whole process of concrete production. This paper describes the findings of a survey of Iranian ready mixed plants in order to minimize the land space used by the equipment of batching plants. The problem of batching plant optimization was formulated and a genetic evolutionary algorithm was developed in MATLAB 7.1 in order to facilitate the optimization process. The efficiency of the proposed algorithm is demonstrated with reference to the time and land space used. Applying the model in a case study shows that the model is practicable, and it significantly reduces the land space used while improving other criteria.
... This research referred to the effect of delay on concrete unit cost regarding productivity, cost and delay as the most important factors in RMC plants. As for the factor of cost, cost of equipment was also considered for each cubic meter of concrete [16]. Another research studied a new approach in the control and modeling of batching plants based on automation system. ...
In the U.S.A., 70 percent of the manufactured cement and 43 percent of aggregates is used in Ready-Mixed Concrete (RMC) plants. So a material inventory control system is needed to form a consumption pattern for this material to optimize warehousing cost and ordering in RMC plants. Such a material inventory control system of batching plants could be applied as an approach for optimal estimation of the reservoirs required for storage and feeding of material. In this research, a material inventory control system of batching plants has been developed by fuzzy logic (FL) with Economic Order Quantity (EOQ) model of inventory control. 70% and 80% reduction has been obtained in estimation of optimal size of the required reservoirs for aggregate and cement respectively in one of the RMC plants of Tehran in the FL model, which reduced the required land used for the plant and maintenance and manpower expenses.
... The average (mean) values of the weights, standard deviation, standard error, lower and upper values for a 68% level of confidence, and similarly for a 95% level of confidence were evaluated. Statistical tests -the Chi-Squared, the Anderson-Darling, and the Kolmogorov-Smirnov tests -were performed (Zayed and Nosair, 2006). Tables for CT and TT are also produced but not shown due to paper size limitation. ...
Performance of subway stations is a critical problem that faces public transit authorities worldwide. Although replacing subway stations is very expensive, the Société de Transport de Montreal (STM) and most transit authorities lack planning strategies because they do not have deterioration models for their infrastructure. The presented research in this paper assists in developing a stochastic Global Station Diagnosis Model (GSDM). The GSDM identifies and evaluates the weights of different functional condition criteria for subway stations. It also utilizes the Preference Ranking Organization Method of Enrichment Evaluation (PROMETHEE) integrated with the Multi-Attribute Utility Theory (MAUT) and Monte Carlo simulation in order to determine a stochastic Global Diagnosis Index (GDI). Data were collected from experts through questionnaires and interviews. A case study of subway stations from the STM network is selected to implement the designed model. Results show that the GDI for the case study stations ranges from 5.6 to 7.8 with a 95% probability. Performing sensitivity analysis, the ‘Alarm and Security’ criterion is found to be the most effective criterion on the GDI. This research is relevant to industry practitioners and researchers since it provides a stochastic diagnostic tool for subway stations.
... Therefore, finding potential causes of schedule delays is important in resolving delay problems before they actually occur. Previous studies focused on identifying significant causes of delay (e.g., Assaf et al. 1995 ), quantifying general delay impacts by advanced techniques [Oliveros and Fayek (2005) employed a fuzzy logic approach to quantify delay events and to modify activity and project durations], or measuring the delay impact from specified delay events [e.g., Zayed and Nosair (2006) evaluated the delay impact on cost for a concrete batch plant using stochastic mathematical models]. Consequently, these studies investigated the key cause of delays, but failed to examine how identified causes work together to influence schedule delays. ...
Schedule delays frequently occur in construction projects. The first step in resolving delay problems is to identify the main causes of delay. Previous studies identifying significant causes of delay have not examined how different causes work together to influence project schedule delays. Structural equation modeling (SEM) of causes of delay in construction has been developed for describing and quantifying the influence of different causes. Although this empirical study is based on a survey in Taiwan's construction environment, the proposed model is applicable to construction industries in other countries. The analytical results clearly show the correlations among key causes of delay, which is the basis for resolving future schedule delays. This study proved that SEM is capable of quantifying the comprehensive relationships among investigated factors. Additionally, SEM has a high potential to resolve experience-oriented problems in the construction industry.
