Prediction of Thermal Behavior of Pervious Concrete Pavements in Winter

Because application of pervious concrete pavement (PCPs) has extended to cold-climate regions of the United States, the safety and mobility of PCP installations during the winter season need to be maintained. Timely application of salt, anti-icing, and deicing agents for ice/snow control is most effective in providing sufficient surface friction when done at a suitable pavement surface temperature. The aim of this project was to determine the thermal properties of PCP during the winter season, and to develop a theoretical model to predict PCP surface temperature. The project included a laboratory and a field component. In the laboratory, thermal conductivity of pervious concrete was determined. A linear relationship was established between thermal conductivity and porosity for pervious concrete specimens. In the field, the pavement temperature in a PCP sidewalk installation at Washington State University was monitored via in-pavement instrumentation. Based on the field data, the Enhanced Integrated Climatic Model (EICM) was developed and validated for the site, using PCP thermal properties and local climatic data. The EICM-predicted PCP surface temperature during the winter season agreed well with the field temperature. Overall, the predicted number of days that the pavement surface fell below 32°F agreed well with the number based on field data for 85% of the days. Therefore, the developed model is useful in identifying those days to apply deicer agents. Finally, a regression model using climatic indices was developed for PCP surface temperature prediction in the absence of a more advanced temperature model

EVALUATION PAVEMENT DISTRESSES USING PAVEMENT CONDITION INDEX

Pavement deterioration is resulted by both environmental and structural causes. It is difficult to maintain the road on the same specification that was owned at the opening and problems start to appear represented in the pavement cracks, holes and undulations and so on. Recognizing defects and understanding their causes helps us rate pavement condition and select cost-effective repairs. Periodic inspection is necessary to provide current and useful evaluation data. It is recommended that ratings be updated every year. Maintenance is an essential practice in providing for the long-term performance and the esthetic appearance of an asphalt pavement. The purpose of pavement maintenance is to correct deficiencies caused by distresses and to protect the pavement from further damage. A condition rating of the pavement will help determine what pavement maintenance technique is necessary. A methodology was proposed to investigate the pavement condition; this study focuses on flexible pavement. A manual survey is performed following ASTM D 6433. The pavement is divided into sections. Each section is divided into sample units. The type and severity of sample distress is assessed by visual inspection of the pavement sample units and the quantity of each distress is measured. Typically, this procedure requires a team of at least two engineers. The pavement evaluation results from the manual PCI survey revealed that all sections of road were fair condition. Considered the section of road that surveyed, describing the condition pavement of the all road. The pavement that has been studied at Koums area would seem to require maintenance. Thick overlay (sometimes called surface treating) is needed in a comprehensive pavement

Contributions to predicting contaminant leaching from secondary materials used in roads

Slags, coal ashes, and other secondary materials can be used in road construction. Both traditional and secondary materials used in roads may contain contaminants that may leach and pollute the groundwater. The goal of this research was to further the understanding of leaching and transport of contaminants from pavement materials. Towards this goal, a new probabilistic framework was introduced which provided a structured guidance for selecting the appropriate model, incorporating uncertainty, variability, and expert opinion, and interpreting results for decision making. In addition to the framework, specific contributions were made in pavement and embankment hydrology and reactive transport, Bayesian statistics, and aqueous geochemistry of leaching. Contributions on water movement and reactive transport in highways included probabilistic prediction of leaching in an embankment, and scenario analyses of leaching and transport in pavements using HYDRUS2D, a contaminant fate and transport model. Water flow in a Minnesota highway embankment was replicated by Bayesian calibration of hydrological parameters against water content data. Extent of leaching of Cd from a coal fly ash was estimated. Two dimensional simulations of various scenarios showed that salts in the base layer of pavements are depleted within the first year whereas the metals may never reach the groundwater if the pavement is built on adsorbing soils. Aqueous concentrations immediately above the groundwater estimated for intact and damaged pavements can be used for regulators to determine the acceptability of various recycled materials. Contributions in the aqueous geochemistry of leaching included a new modeling approach for leaching of anions and cations from complex matrices such as weathered steel slag. The novelty of the method was its simultaneous inclusion of sorption and solubility controls for multiple analytes. The developed model showed that leaching of SO4, Cr, As, Si, Ca, Mg, and V were controlled by corresponding soluble solids. Leaching of Pb was controlled by Pb(VO4)3 solubility at low pHs and by surface precipitation reactions at high pHs. Leaching of Cd and Zn were controlled by surface complexation and surface precipitation, respectively

Technology News, October-December 2014

Technology News is a newsletter produced by the Iowa Department of Transportation to provide information to the transportation specialist in Iowa's cities and counties. Technology News is one of CTRE's primary avenues for exchanging transportation-related information with local agencies. The bimonthly newsletter gives an up-to-date look to the up-to-date information our 2,500+ readers have grown to expect

Performance-based Re-use of Tunnel Muck as Granular Material for Subgrade and Sub-base Formation in Road Construction

Large volumes of muck are produced in the Alpine Region and bordering areas as a result of new road and railway construction. For example, in Austria every year approximately 32*10^6 Mg of muck are produced from tunnelling activities. In the near future, many other initiatives along the European corridors will lead to further construction activity, with an inevitable increase in the environmental problems related to the use or disposal of the muck generated. Therefore, there is a clear opportunity for the extensive re-use of muck due to the high demand for granular materials (about 3 billion tonnes in Europe, only 5% of which comes from recycling), the depletion of existing quarries (approximately 24,000 in Europe), and the environmental constraints preventing or delaying the opening of new quarries. In this scenario, a new approach to the re-use of muck is both necessary and timely. Although many typical defects deriving from its geological nature and/or from the extraction techniques employed may lead to its rejection as an aggregate, these same defects are of less importance in embankment, subgrade and sub-base construction in transportation infrastructures and, indeed, in most cases they can be mitigated by granular or chemical stabilization. The investigation described here embraces this philosophy. Starting from the chemical physical characterization of seven different mucks derived from tunnelling activities on the Italian side of the Alps, the paper aims to explore the potential benefits deriving from their re use as a construction material. The test methods used all adhere to prescriptive and performance based construction specifications. Notwithstanding the unfavourable geological origin of some of the considered materials, they all exhibited mechanical properties that would encourage their almost complete re-use in infrastructure construction projects

Field investigation of deformation characteristics and stress mobilisation of a soil slope

Stress mobilisation and deformation of a slope are important for engineers to carry out reliable design of retaining systems. However, most case histories reported mainly on the response of pore-water pressure (PWP), whereas knowledge about the stress-deformation characteristics of slope is limited. In this study, a saprolitic soil slope was instrumented to monitor not only the responses of PWP but also horizontal stress and horizontal displacement. To assist in the interpretation of field data, a series of laboratory tests was conducted to characterise the volume change behaviour of soil taken from the site, under the effects of both net stress and suction. During a rainstorm event when positive PWP built up, a remarkably large displacement of 20 mm was recorded between 5.5 and 6 m depths, and the top 5 m of the slope exhibited translational down-slope movement. This caused an increase in effective horizontal stress by 350%, which reached a peak value close to 40% of an effective passive stress. During the subsequent dry season when suction was recovered, an up-slope rebound of 10 mm was recorded. Comparison of field and laboratory data reveals that the rebound was attributed to suction-induced soil shrinkage. This rebound led to a decrease in the effective horizontal stress previously built up during the storm event

Seasonally Frozen Soil Effects on the Seismic Performance of Highway Bridges

INE/AUTC 12.0

Effect of Fillers on Bituminous Paving Mixes

Construction of highway involves huge outlay of investment. A precise engineering design may save considerable investment; as well as reliable performance of the in-service highway can be achieved. Two things are of major considerations in this regard – pavement design and the mix design. Our project emphasizes on the mix design considerations. A good design of bituminous mix is expected to result in a mix which is adequately strong, durable and resistive to fatigue and permanent deformation and at the same time environment friendly and economical. A mix designer tries to achieve these requirements through a number of tests on the mix with varied proportions of material combinations and finalizes the best one. This often involves a balance between mutually conflicting parameters. Bitumen mix design is a delicate balancing act among the proportions of various aggregate sizes and bitumen content. For a given aggregate gradation, the optimum bitumen content is estimated by satisfying a number of mix design parameters. Fillers play an important role in engineering properties of bituminous paving mixes. Conventionally stone dust, cement and lime are used as fillers. An attempt has been made in this investigation to assess the influence of non-conventional and cheap fillers such as brick dust and fly ash in bitumen paving mixes. It has been observed as a result of this project that bituminous mixes with these non-conventional fillers result in satisfactory Marshall Properties though requiring a bit higher bitumen content, thus substantiating the need for its use. The fillers used in this investigation are likely to partly solve the solid waste disposal of the environment