Review of advanced road materials, structures, equipment, and detection technologies

As a vital and integral component of transportation infrastructure,pavement has a direct and tangible impact on socio-economic sustainability.In recent years,an influx of groundbreaking and state-of-the-art materials,structures,equipment,and detection technologies related to road engineering have continually and progressively emerged,reshaping the landscape of pavement systems.There is a pressing and growing need for a timely summarization of the current research status and a clear identification of future research directions in these advanced and evolving technologies.Therefore,Journal of Road Engineering has undertaken the significant initiative of introducing a comprehensive review paper with the overarching theme of“advanced road materials,structures,equipment,and detection technologies”.This extensive and insightful review meticulously gathers and synthesizes research findings from 39 distinguished scholars,all of whom are affiliated with 19 renowned universities or research institutions specializing in the diverse and multidimensional field of highway engineering.It covers the current state and anticipates future development directions in the four major and interconnected domains of road engineering:advanced road materials,advanced road structures and performance evaluation,advanced road construction equipment and technology,and advanced road detection and assessment technologies.

Review on constitutive models of road materials

Road material constitutive model is the essential condition of pavement structure design,calculation,and maintenance decision.Experts have conducted in-depth studies on the problems and proposed many meaningful constitutive models.However,these constitutive models have not been summarized and no uniform conclusion on the applicability of them is reported in the academic circle.The linear elastic model based on Hooke's law is still used in pavement structure design.This paper systematically reviewed the existing constitutive models that reflect the materials'mechanical properties and used for pavement structure calculation.These constitutive models were divided into three categories:linear,nonlinear,and damage models under repeated loads.The applicable conditions,parameter determination methods,advantages,and disadvantages of each model were introduced.Moreover,the model's feasibility in structural design and calculation was analyzed.Follow-up studies should focus on the parameter determination standard of viscoelastic constitutive models,the extension of the 1D constitutive model to 3D state,and the nonlinear constitutive models related to stress-strain state to drive the application of the constitutive models in pavement structure calculation and design.Furthermore,to evaluate the life cycle service performance of road materials and structures,establishing the pavement damage model from the structure perspective will be the future direction.

Materials,preparation,performances and mechanism of polyurethane modified asphalt and its mixture:A systematic review

With the rapid development of asphalt pavement technology,it has attracted considerable attention to improving the durability of asphalt pavement.An effective action is to use modified asphalt with high performance and durability.Polyurethane(PU)has been used in asphalt pavement engineering to enhance the durability and service life of asphalt pavement because of its excellent high-temperature performance,toughness,wear resistance,aging resistance and oil resistance.However,PU modified asphalt technology is still in the exploratory stage.The preparation,modification mechanism and working performances of PU modified asphalt need to be further clarified.Therefore,this paper summarized the research progress of PU modified asphalt and its mixture.The composition of PU modified asphalt was introduced.The addition methods of PU materials and preparation process parameters of the PU modified asphalt were determined.The modification mechanism of PU on asphalt was discussed.The effects of polyurethane on asphalt were analyzed and the road performances of its mixture were evaluated.Finally,the development tendency towards PU modified asphalt and its mixture were forecasted.

The Properties of Road Base Course Materials of Granular Soils Stabilized by AGS Granular Soil Stabilizing Cement

The properties of road base course materials of granular soils stabilized by AGS granular soil stabilizing cement were studied.The AGS cement has an expansibility to a certain degree,so the dry shrinkage of AGS cement paste and AGS stabilized granular is much lower than that of Portland slag cement.AGS has a good suitability to granular soils.Granular soils stabilized by AGS have a much higher strength than that of soils stabilized by P S cement.The same strength can be reached with 20% reduction of cement dosage for AGS cement.And their elastic and resilient modulus are similar,but the former has a much higher tensile splitting strength,so the AGS stabilized granular has a much better anti-cracking performance than that of the P S stabilized granular.The reduced value of the strength and the density with the retard time for the granular soils stabilized by AGS is lower than that for P S cement.

A review of converting woody biomass waste into useful and eco-friendly road materials

Because of abundant reserves and renewable and environmentally friendly properties,the utilization of woody biomass waste in road engineering can alleviate the shortage of fossil fuels and carbon emissions so as to mitigate global climate change and achieve sustainable development of road engineering.This paper synthesizes the state of the art about the strategies of applying five kinds of resources derived from waste woody biomass,including biochar,bio-oil,lignin,wood ash and nanocellulose to road construction.Based on the characteristics analysis of the five materials,it can be concluded that biochar can comprehensively improve the road performance of asphalt and its mixtures,and has the potential of runoff purification;bio-oil can soften asphalt and improve its lowtemperature performance,but has negative effects on high-temperature performance;lignin increases the asphalt ageing resistance and can be used as a regenerant,and will improve the overall performance of asphalt mixtures if combined with other modifiers;wood ash can increase subgrade bearing capacity and bring significant environmental benefits;nanocellulose improves the strength of cement mortar,but there is a lack of research on its effects on performance of pavement materials and the interaction mechanism;the lifecycle environmental and economic assessment of woody biomass-modified road materials is not comprehensive.Moreover,prospects were also summarized to show the opportunities for future study,such as the establishment of a database for biomass.This review provides useful insights for the utilization of woody biomass as road materials to achieve waste management and sustainable development.

Moroccan Phosphogypsum Use in Road Engineering:Materials and Structure Optimization

Morocco produces annually large quantities of phosphogypsum(PG),which permanent stacking rises technical and environmental constraints.However,the valorization of this coproduct in civil engineering and especially in roads building,is a promising solution within a circular economy frame.A first experimental one-kilometer-long pilot,incorporating four different PG based formulations with a 7%cement addition,built at Safi in 2017,allowed positive mechanical assessment(by deflector)and environmental one(by leaching test).In order to further evaluate PG use as road material,our experimental approach focuses here on optimizing material mixtures-made of phosphogypsum(maximum content desired)treated with cement(to be minimized so as to reduce the cost)and sand or steel slag as granular corrector-to meet mechanical requirements of a road base material.We first identified and characterized phosphogypsum produced at the Jorf Lasfar plant and other materials used.Design of experiment is used for modeling desired physical and mechanical responses and to establish domains meeting the required criteria for using the mixture material either as road subgrade layer or foundation layer.In addition,through a parametric study,we evaluated the effects of traffic level,soil bearing capacity and mechanical performance of treated phosphogypsum mixtures on pavement design for three different pavement structures(mixed,reverse and structure with treated sub-base)and determined that the best to adopt for maximizing PG recycling is the pavement structure with subbase treated with hydraulic binder.

Resilient Modulus of Hydraulically Bound Road Base Materials with High Volume Waste Dust

The paper presents laboratory test results on hydraulically bound road base materials containing high volume of steel slag and blast furnace slag waste dusts compared with control mixtures. These mixtures contain higher levels of （4mm-0.0 mm） dust, than would be the case in standard un bound road base mixtures. The combined influence of the steel slag and granulated blast furnace slag wastes content is to enhance the stiffness of the road base materials and save materials and cost during road construction. Triaxial repeated load tests were performed on the unbound and lightly bound materials to measure their resilient modulus. The test results show important improvements in the bond strength between the contents of road base materials. This offers the prospect of using these materials in road base materials to reduce the use of primary aggregates and thus minimize the cost of roads and highways construction.

Research Progress of Epoxy Asphalt Material for Roads

Asphalt is a semi-solid or solid mixture formed by hydrocarbons and non-metallic elements.It is widely applied in the fields of building waterproofing and road paving.Asphalt is a low noise,durable,and renewable pavement material.However,asphalt materials have some shortcomings such as liquefying at high temperatures and brittleness at low temperatures,which are less adaptable to different environments.Therefore,people have gradually shifted their focus to asphalt modification.This paper presents an in-depth analysis and research on the composition,structure,and performance of epoxy asphalt materials for roads,so that this material can be widely used.

RESEARCH ON THE HIGH PERFORMANCE COMPOSITE ROAD CONCRETE

Ordinary concrete presents short service life when used for building and repairing high-grade road with heavy traffic due to its large brittleness, poor bending flexibility and serious shrinkage on drying. In this paper, a new kind of high performance concrete has been designed by means of combination of organic, inorganic material as well as metal material. The research and application have shown that this new concrete can significantly counteract the deficiency of ordinary concrete and give excellent mechanical properties and pavement performances. The application of this new kind of concrete is of great social and economic significance.

Assessing Gravel Roads Condition to Examine Trends and Behaviors of Gravel Roads in Rural Areas in Kyela District

Gravel roads are an economical choice where traffic volume is low. Many gravel roads were constructed in rural areas in the Kyela district and they were well-served for many years. Besides the gravel roads, the main challenge faced is the issue of unpaved road condition deterioration by the behaviors of road materials. The study selected three gravel rural roads with a total of 31.24 kilometers as constructed roads to gravel standard. The aim of this study was to assess gravel roads condition to examine trends and behaviors of gravel roads in rural areas. A descriptive analysis was conducted to determine trends and behaviors of gravel roads. The methods used to collect data were observation and physical measurement. The results show that there was more than one road distress identified and assessed on each study road. It was noted that all the study roads had excellent to poor distress conditions associated with poor road materials and lack of maintenance. This study recommended that road authorities improve the current condition by avoiding the use of poor road materials in order to reduce surface deterioration associated.

Evaluation and Selection of Sealants and Fillers Using Principal Component Analysis for Cracks in Asphalt Concrete Pavements

The objective of this paper was to develop a comprehensive evaluation method and index to evaluate the performance of sealants and fillers for cracks in asphalt concrete pavements using the method of principal component analysis. The performance experiments including cone penetration, softening point, flow, resilience and tension at low temperature respectively were conducted by reference of ASTM D5329 for eight sealants and fillers often used in China. There by a principal component model was developed and weight of every index was calculated. The experimental results show that there are significantly different performances for sealants and fillers often used in China. Principal component analysis is an objective method that evaluates and selects the performance of sealants and fillers for cracks in asphalt concrete pavements.