DEVELOPMENT OF PREDICTION MODELS OF HIGH TEMPERATURE CRUMB RUBBER MODIFIED BINDERS

The purpose of this research was to identify and model critical elements of the asphalt rubber matrix contributing to the crumb rubber modified (CRM) binder properties as measured by Superpave testing procedures. Current models are neither applicable (due to new testing procedures) nor practical (due to the difficulty of application or lack of accuracy). Therefore, this research investigated the development of predictive models for estimating binder properties within a specified range of accuracy. Multiple crumb rubber sources were evaluated in order to gain an understanding of the differences between the various crumb rubbers. This analysis permitted identification of the important parameters, thus allowing for an accurate model to be developed. Analysis of the crumb rubber particles involved the determination of the glass transition temperature, chemical and visual analysis by scanning electron microscope. Once the critical parameters were established, other test data was obtained from research projects conducted at other labs. This allowed a broader model to be developed, a model which would not be specific to one specific tester and a lab facility. Ultimately a total of 17 virgin binder sources from 10 separate regions were evaluated; a further 12 crumb rubber sources were used in conjunction with the various binder sources. The nonlinear empirical models for estimation of CRM binder properties were developed using the nonlinear least squares method. The accuracy of the various models was evaluated by identifying 95% confidence intervals for the binder property estimation. Validation of the models was performed using a fractional factorial design with previously untested CRM binders and this step confirmed the accuracy of the various models. Findings suggest that the effect of the crumb rubber in the binder tends to magnify the effects of the base binder. This indicates that, for CRM binder, the properties of the base binder typically have a greater influence on CRM binder properties than the properties of the crumb rubber used in the matrix. It was possible to develop empirical models depicting the changes in viscosities, G*/sinδ values, and failure temperatures. The Rubber coefficient for viscosity (Rcv) and G*/sinδ (Rcg) were important parameters when estimating CRM binder properties. These coefficients are representative of the effects of the various crumb rubbers on the binders; generally, it was seen that ambient crumb rubbers had higher Rcv and Rcg values than cryogenic rubbers

Development of prediction models of high temperature crumb rubber modified binders

The purpose of this research was to identify and model critical elements of the asphalt rubber matrix contributing to the crumb rubber modified (CRM) binder properties as measured by Superpave testing procedures. Current models are neither applicable (due to new testing procedures) nor practical (due to the difficulty of application or lack of accuracy). Therefore, this research investigated the development of predictive models for estimating binder properties within a specified range of accuracy. Multiple crumb rubber sources were evaluated in order to gain an understanding of the differences between the various crumb rubbers. This analysis permitted identification of the important parameters, thus allowing for an accurate model to be developed. Analysis of the crumb rubber particles involved the determination of the glass transition temperature, chemical and visual analysis by scanning electron microscope. Once the critical parameters were established, other test data was obtained from research projects conducted at other labs. This allowed a broader model to be developed, a model which would not be specific to one specific tester and lab facility. Ultimately a total of 17 virgin binder sources from 10 separate regions were evaluated; a further 12 crumb rubber sources were used in conjunction with the various binder sources. The nonlinear empirical models for estimation of CRM binder properties were developed using the nonlinear least squares method. The accuracy of the various models was evaluated by identifying 95% confidence intervals for the binder property estimation. Validation of the models was performed using a fractional factorial design with previously untested CRM binders and this step confirmed the accuracy of the various models. Findings suggest that the effect of the crumb rubber in the binder tends to enhance the effects of the base binder. This indicates that, for CRM binder, the properties of the base binder typically have a greater influence on CRM binder properties than the properties of the crumb rubber used in the matrix. It was possible to develop empirical models depicting the changes in viscosities, G*/sinδ values, and failure temperatures. The Rubber coefficient for viscosity (Rcv) and G*/sin[special characters omitted] (Rcg) were important parameters when estimating CRM binder properties. These coefficients are representative of the effects of the various crumb rubbers on the binders; generally, it was seen that ambient crumb rubbers had higher Rcv and Rcg values than cryogenic rubbers

Review of Asphalt Pavement Evaluation Methods and Current Applications in Norway

Evaluation methods and tools used to assess pavement conditions provide an invaluable service to infrastructure engineers, technicians, budget planners, and decision makers. These tools provide information relevant to the maintenance and rehabilitation of a nation’s infrastructure. As the pavement network continues to grow and age, new methods of condition evaluation will need to be implemented to maintain conditions databases so that managers and decision makers may develop accurate ideas with regards to the state of the network. This paper introduces various concepts and technologies used today within the road evaluation sector, these include: sensor technologies, pavement condition surveys, imaging techniques, deflection testing, and ground penetrating radar (GPR). These technologies are then discussed within the Norwegian context and their applicability reviewed

Cost Development Over-time at Construction Planning Phase: Empirical Evidence from Norwegian Construction Projects

AbstractEvery capital-intensive constructions project goes through various challenges throughout their project life cycle. However, one crucial challenge is to understand and trace cost development over-time at planning phase. The research aim is threefold: firstly, to identify the critical factors of cost development in the planning phase. Secondly, to investigate empirically a dyadic relationship of cost deviation over time and quantitatively chart their developments. Thirdly, to analyze the construction cost data, discuss their cost developments and identify critical projects based on their actual financial impacts. The research considers 110 projects and analyze them using qualitative and quantitative research methods. The results showed higher cost escalation in the planning phase. The research identified critical factors for cost escalations at the planning phase. The average cost escalation of 110 projects (<5%) seems good, but some projects showed large cost deviations with lower financial impacts and vice versa

FRP APPLICATIONS IN LOW-DISTURBANCE, SUSTAINABLE URBAN INFRASTRUCTURE

The on-going European project PANTURA (www.pantura-project.eu) is dealing with new methods, tools and techniques for building, maintaining and improving bridges in urban environments in an efficient, sustainable way with a minimum of disturbance for inhabitants and disruption of mobility. The project has a multidisciplinary character and includes construction processes, newly developed IT tools, a new, integrated design and engineering solutions for flexible off- and on-site fabrication, construction techniques and on-site assembly methods and the rehabilitation and strengthening of old bridges. The work is conducted based on identified and evaluated indicators, best practices and benchmarking of assessment tools. The presented results are partly related to development of set of indicators and a tool to help decision makers to choose sustainable bridge concepts; and partly related to FRP application as a possible sustainable solution. An example is based on the case study FRP bridge in La Palma. It is shown that FRP materials are very well suited as a reinforcement material to strengthen existing bridges. MCDA tool is a good method to compare various materials for off- and on-site industrial fabrication of new bridges and FRP offers sustainable solutions and many advantages

FRP APPLICATIONS IN LOW-DISTURBANCE, SUSTAINABLE URBAN INFRASTRUCTURE

The on-going European project PANTURA (www.pantura-project.eu) is dealing with new methods, tools and techniques for building, maintaining and improving bridges in urban environments in an efficient, sustainable way with a minimum of disturbance for inhabitants and disruption of mobility. The project has a multidisciplinary character and includes construction processes, newly developed IT tools, a new, integrated design and engineering solutions for flexible off- and on-site fabrication, construction techniques and on-site assembly methods and the rehabilitation and strengthening of old bridges. The work is conducted based on identified and evaluated indicators, best practices and benchmarking of assessment tools. The presented results are partly related to development of set of indicators and a tool to help decision makers to choose sustainable bridge concepts; and partly related to FRP application as a possible sustainable solution. An example is based on the case study FRP bridge in La Palma. It is shown that FRP materials are very well suited as a reinforcement material to strengthen existing bridges. MCDA tool is a good method to compare various materials for off- and on-site industrial fabrication of new bridges and FRP offers sustainable solutions and many advantages