While recycling technologies offer solution to the challenges associated with end-of-life tires (ELT), the reliance of the industry on nonrenewable sources raises concerns. The objective of this cradle-to-gate lifecycle assessment study was to quantify the potential environmental impacts due to recycling of ELT into multiple outputs: crumb rubber (CR), micronized rubber powder (MRP), and reclaimed rubber (RR). Thirty-six scenarios were analyzed including three products and two ELT sources using six electricity mix scenarios transitioning the nonrenewable to renewable sources. The global warming potential due to the production of CR, MRP, and RR from domestic ELT were 1.13 × 10⁴, 3 × 10⁴, and 3.63 × 10⁴ kg CO₂ eq., respectively, while 50 % transition to renewables reduced them by 10–15 %. Further, MRP showed the highest land occupation and water consumption potential. Overall, this research provided a holistic overview of current and future impacts of tire recycling industry supporting sustainable practices.

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The objective of this research was to evaluate the lifecycle costs associated with emerging pavement maintenance technologies, namely, in-situ rejuvenation and very open emulsion asphalt concrete (ZOEAB+), and scrutinise their suitability over corrective resurfacing maintenance using a stochastic approach. A rational lifecycle inventory was developed by conducting interviews and questionnaire surveys with experts and referring to standard guidelines and international databases. The net present value (NPV) was found sensitive to 12 different inputs with traffic growth rate and discount rate causing the highest uncertainty followed by gasoline and diesel prices. Monte Carlo simulations suggested that the median uncertainty in NPV by using in-situ rejuvenation and ZOEAB+ was 13% and 4% lower than resurfacing. It is envisioned that the research outcomes will assist decision-makers in understanding the uncertainties and costs associated with different maintenance alternatives in the early stages of the project to foster procurement of sustainable and circular pavement maintenance strategies.

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This chapter presents the effects of using crumb rubber (CR) and aircraft composite wastes (CW) on pervious concrete (PC) characteristics and outlines the systematic framework for lifecycle assessment (LCA) of PC pavement (PCP) systems. The incorporation of fine CR (1.18–0.15 mm) in PC resulted in improved mechanical properties, while maintaining the desired functional attributes. Though the addition of CW in PC did not alter the PC properties significantly, it allowed for the disposal of 1.47–3.90 t of CW in one-lane km PCP. LCA indicated no major differences between the environmental impacts of control and CW-modified PC. Furthermore, the environmental burdens of PCP were lower than the cement concrete pavements by about 3%. This chapter is intended to serve as an important repository that paves the way for research and implementation of the PCP products engineered with recycled waste materials, thereby serving as a low-impact development strategy for green urban infrastructure.@en

Refurbishing of milled asphalt into new bound layers of pavement is recognized as a sustainable maintenance practice. However, limited attention has been paid towards investigating their circularity aspects. Furthermore, evolving legislative requirements call for integration of circularity and sustainability facets. Therefore, this study presents a flexible framework that aims at assessing and integrating the environmental, economic, and circularity aspects associated with two maintenance alternatives, i.e., reconstruction of pavement with a bound base layer using bituminous materials (BSM) versus routine patch repair and resurfacing. The integration of different assessment categories was performed using a metric termed as net risk reduction gain (NRRG). The results revealed that the NRRG for BSM option was 2.5 times higher than routine maintenance over a 50 year analysis period, thereby emphasizing its higher circularity and sustainability benefits. The proposed framework is envisioned to pave way for integration of circular thinking along with sustainability considerations for pavement design and construction.@en

Although multiple studies have reviewed the mechanical, durability, and acoustic characteristics of rubberized concrete (RC) mixtures, very limited studies have focused on a comprehensive collation of literature pertaining to their environmental, economic, and field implementation aspects. Therefore, this paper presented the state-of-the-art pertinent to environmental and economic aspects, thermal savings in terms of energy and emissions, and field applications of RC mixtures. Further, none of the studies have systematically reviewed the literature specific to specialty RC mixtures (pervious concrete, self-compacting concrete, and roller-compacted concrete), which was thoroughly examined. The various rubber treatment methodologies to enhance rubber-cement interaction were underscored and the impact of rubber aggregates on mix properties was discussed. Importantly, this state-of-the-art review identified the scope for future advancements at environmental, economic, and technical levels, which is envisioned to advance the widespread implementation of RC and pave the way for creation of an eco-efficient built environment.

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The use of nondestructive ultrasonic pulse velocity (UPV) testing to assess the hardened properties of pervious concrete (PC) mixtures is an emerging research area. Further, UPV has been successfully used to determine the effective flow resistivity (EFR) of asphalt concrete and cement concrete pavements. However, no research studies have focused on understanding PC characteristics using EFR. Thus, the major objectives of this study were to assess the suitability of UPV testing for characterizing PC mixtures and to quantify their EFR, which is a measure of the material’s characteristic impedance and is dependent on the mix variables along with porosity. Thirty-six control and sand-modified PC mixtures were prepared with four aggregate gradations, and three levels each of water-to-cement (w/c) and aggregate-to-cement (a/c) ratios. Test results indicated that EFR was significantly dependent on the mix variables, with aggregate gradation being the most influential factor (six and eight times higher than w/c and a/c ratios, respectively). Lower EFR or higher sound absorption capacity was reported for PC with higher porosities. The sand-modified PC mixtures had higher EFR (by 4%–12%) than the control PC, and consequently lower sound absorption capacity, attributed to the presence of mortar that densified the mixes. Further, good-to-excellent correlations were obtained for various PC properties with UPV and EFR, which underscored the potential of UPV in characterizing PC. The major contribution of this research was the development of a simple, fast, and cost-effective approach, which can be suitably adopted as a quality-control test to determine PC mixture properties.

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Implementation of the circular economy and resource efficiency has the potential to significantly tackle the root causes of global challenges such as climate change, biodiversity loss and pollution whilst at the same time providing regenerative design for generations to come. The CEDR funded CERCOM project facilitates a move towards circular public procurement of national road infrastructure. A flexible and stable approach using ranked interpolation is used to generate KPI values for various criterion, where the user can specify the desired level of complexity based on scheme requirements and data available. The framework considers technical, economic, environmental and social criteria, as well as circularity, while assessing the change in risks in moving from a linear to a circular economy. National Road Authorities (NRAs) are at different maturity levels in relation to circularity. The developed framework caters for this, allowing flexibility for NRAs to tailor their application of the framework to suit their maturity level and the scheme under consideration. The outcome is a user-friendly intuitive tool with a step-by-step approach to enable informed decision making around adoption of the principles of circular economy in the maintenance of highway infrastructure.@en

This paper presents laboratory investigations on Plastic-Rubber Modified Bitumen (PRMB), a modified asphalt binder that was produced with waste plastics and Crumb Rubber (CR) inclusions obtained from discarded tires and additives. The final proportions of waste components and additives were reported as 90 and 10% in the total 100% blend of PRMB. A detailed laboratory study was conducted to obtain the fundamental consistency and advanced rheological characteristics of the developed PRMB and compared with Viscosity Graded (VG 30) binder, Crumb Rubber Modified Bitumen (CRMB 60), and Polymer Modified Bitumen (PMB). The softening point temperatures and viscosities at elevated temperatures of PRMB were found to be higher than VG 30 and CRMB 60. Additionally, the viscosity of PRMB at 150℃ was about 1.04 Pa.s, which was less the maximum value of 1.2 Pa.s specified for PMB 70-10 and PMB 76-10 in IS:15462-2019. Based on the results of upper Performance Grade (PG), failure temperature (PG 88-XX), and loss in the elastic recovery (@en

Pervious concrete pavements (PCP) have been successfully constructed in low-to-medium volume roads attributed to their sustainability benefits. Several studies have investigated the hydrological performance of PCPs, but limited attention has been given to the structural and environmental aspects. Thus, the objective of this study was to monitor the structural, hydrological and environmental performance of two PCP parking lots built using in-situ and ready-mix methods. Structural distresses were classified based on the distress identification manual, while the infiltration tests were performed every three months for three years to quantify the clogging rate. Joints/edges formed the weakest zones, while inefficient maintenance caused 98% clogging within 18 months. Further, in-situ mixing was 17% cheaper and 0.74% carbon-intensive than ready-mix technology. Overall, this research is envisioned to pave way for the development of guidelines that classify distresses and severity levels specific to PCPs, which also cover adequate maintenance recommendations for field implementation.

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Conversion of pervious natural ground into impermeable pavement systems has caused severe environmental impacts such as urban heat islands, increased infrastructure-related greenhouse gas (GHG) emissions and energy consumption, and runoff generation / flashfloods during rainfall events. These phenomena can be addressed with the use of pervious concrete pavement (PCP) systems, which have gained acceptance as sustainable alternatives to conventional materials. However, implementation of PCP technology is limited to low-volume roads, sidewalks, and parking lots attributed to low strength and the need for high quality control during construction compared to traditional pavements along with limited understanding on the end-of-life significance due to the green PCP product. Therefore, the major objective of this research was to develop a pavement system with superior structural and hydrological performance characteristics over traditional PCP, while also quantifying the energy consumed, amount of GHG produced, and costs associated with its design and construction. Thus, a Pervious All-Road All-weather Multilayered pavement (PARAMpave) was conceptualized and designed that comprised a 300 mm square paver block created with a 60 mm lower structural layer overlaid with a 30 mm water-draining surface wearing course pervious concrete layer. The major properties of PARAMpave products included porosity ranging from 17% to 24%, permeability varying from 0.77 cm/s to 1.33 cm/s, and flexural strength between 4.83 MPa and 6.13 MPa, indicating their improved structural and hydrological performance compared to traditional designs. Further, a cradle-to-gate lifecycle approach was utilized to perform a comparative evaluation between PARAMpave and Portland cement concrete (PCC) paver blocks. The PARAMpave products consumed lower energy (8.22% to 8.51%) and emitted lower GHGs (8.23% to 8.43%) compared to PCC blocks of similar dimensions. Additionally, PARAMpave blocks were about 10% cheaper and almost 10% lighter than a PCC paver block. The reduction in GHG emissions, energy consumption, and capital costs indicate that PARAMpave blocks are a sustainable class of roadway products. Also, the strength and permeability magnitudes of PARAMpave indicate that they have high potential for applications in different road classes and diversified weather conditions.@en

The sustainable disposal and recycling of composite wastes (CW) after their end-of-life (EOL) has become a serious concern for the composite industry mainly due to the unavailability of efficient recovery routes. Therefore, the objective of this cradle-to-gate study was to examine the suitability of using glass fiber reinforced polymer (GFRP) and carbon fiber reinforced polymer (CFRP) waste in pervious concrete (PC) and quantify their environmental impacts through a lifecycle assessment (LCA) framework. CW were mechanically shredded and
added to PC as reinforcement at dosages of 0.33, 0.65, and 1% by volume of the mix. The various properties of CW modified PC (CW-PC) mixtures were evaluated followed by an LCA investigation to determine the environmental impacts. Test results indicated that incorporation of 0.33% GFRP and 1% CFRP increased flexural strength by about 2 and 5%, respectively, compared to the control PC mix. Further, there was a marginal increase in the short- and long-term
environmental impacts of CW-PC pavement scenarios compared to the control PC mix. However, the environmental impacts caused during the processing and transportation phases of CW were much lower than the burdens generated during raw material production such as cement. Essentially, this preliminary research elucidated significant promise, as it showed that CW can be recycled in PC pavement systems without affecting the performance characteristics. Overall, this study demonstrated that about 1.5 tons of GFRPCW and 3.9 tons of CFRP-CW can be recycled in a single lane km PC pavement, which is consequential of
reducing the amount of CW being disposed in the landfills while positively contributing to the formulation of sustainable waste management practices. @en

Pervious concrete pavement (PCP) systems are engineered roadway technologies that are known to mitigate stormwater runoff attributed to their high porosity. Though significant advancements have been made at the global level, research, and innovation pertinent to PCPs is still emerging in India. Therefore, the objective of this research was to present the evolution of PCP technology in the Indian context. The details pertinent to mix design and characterization, field construction and monitoring, and development of innovative PCP products were presented. Test results indicated that PCPs are suitable for applications in walkways, parking lots, and low-volume roads. It was further observed that the quality control with traditional construction practices was poor resulting in inconsistent mix properties. Though paver blocks offer superior quality products than conventional PCP, they suffer from low strength and maintenance issues. Therefore, recent research focused on designing Pervious All-road class All-weather Multilayered paver (PARAMpave) blocks, whose flexural strength and infiltration rates were higher than 4.8 MPa and 0.77 cm/s, respectively making them suitable for application in all-road-all-weather conditions. Further, PARAMpave consumes lower energy and generates fewer emissions during production. However, additional research must focus on construction of test sections by utilizing pervious concrete paver blocks and PARAMpave products to identify their performance during the design life.@en

The major objective of this study was to evaluate the performance characteristics of control and sand-modified pervious concrete (PC) mixtures through the development of a hybrid multi-criteria decision-making (MCDM) tool to rank the materials and recommend the most optimal performing products. A full-factorial experimentation was adopted to analyse porosity, density, permeability, and compressive strength for 36 PC mixtures. A hybrid MCDM tool involving analytical hierarchy process, Entropy, Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS), and VlseKriterijumskaOptimizacija I Kompromisno Resenje (VIKOR) methods was used to optimize the multi-response problem into a single output. Based on the results, the water-to-cement ratio may be restricted to a maximum of 0.30 and 0.33 for aggregates varying from 9.5 to 6.7 mm and 6.7 to 4.75 mm, respectively. Likewise, the cement-to-aggregate ratio may be restricted to a maximum of 1:3.75 and1:4.25 for aggregate size in the range 9.5–6.7 mm and 6.7–4.75 mm, respectively. Further, the ranks for various PC mixtures obtained from TOPSIS and VIKOR were identical/ similar for about 80% of the mixtures. The proposed MCDM tools are envisioned to help the decision-makers in selecting the most optimum PC mix based on performance and site-specific requirements, a priori pavement design and construction.@en

An alarming increase in the number of waste rubber tires (WRT) generated annually calls for the need to identify sustainable waste management practices as they pose serious threats to the quality-of-life. One such waste disposal strategy is recycling of WRT in pavement materials. Therefore, the objective of this research study was to investigate the effect of inclusion of WRT derived aggregates on properties of pervious concrete (PC). The size of recycled rubber aggregates (RA) varied from 4.75–2.36 mm, which were added to PC mix at 5 and 10% by weight of coarse aggregates; the new mix was called rubber-modified pervious concrete (RMPC). The porosity and permeability increased with increasing proportions of RA with reduction in the density and compressive strength. At 5% RA content; the magnitude of porosity and permeability increased by 6.9 and 53.1%, respectively, while the density and compressive strength reduced by 7.4 and 63.7%, respectively, compared to the control mix. Similarly, at 10% RA content; density and compressive strength decreased by 12.5 and 77.7%, respectively, while porosity and permeability increased by 15.2 and 63.4%, respectively, compared to the control mix. Owing to lower compressive strength (~5–8 MPa), RA as filler may be utilized in PC materials with non-vehicular traffic sections such as sidewalks and footpaths. Due to higher porosity and permeability, RMPC can help harness the stormwater benefits associated with PC, while simultaneously allowing for sustainable disposal of WRT.@en

Embedded infiltration rings have been historically used to estimate the infiltration properties of pervious concrete (PC) pavements. However, no methodical study has evaluated the effect of the size of embedded rings on the infiltration characteristics of these special pavement systems. The objective of this research was to assess the infiltration rate of PC using a multi-scale, in situ approach through embedding rings of various sizes in pavement slabs. Essentially, this investigation attempted to identify the most appropriate size of the embedded ring that can estimate infiltration rates of PC slabs in a reliable manner. To meet the proposed objective, a multi-scale in situ experimental program was designed, in which five infiltration rings of inner diameter ranging from 100 to 580 mm were embedded into three PC slabs of dimensions 3 × 2.5 × 0.15 m. A surface infiltration test was also conducted on PC slabs and was found to vary from 0.36 to 1.87 cm/s. The embedded infiltration rate (EIR) was estimated using a falling head permeability test by ponding water above the pavement surface and measuring the time taken to drain. EIRs decreased from 1.36 to 0.27 cm/s with increasing ring diameter from 100 to 580 mm. Field tests also indicated that infiltration rates for smaller ring diameters (180 mm and lower) had higher uncertainty, which was attributed to the inability of achieving optimum compaction efforts inside of smaller rings. Based on the findings, the optimum size for estimating the infiltration rate of PC was found to be 270 mm. It is noteworthy that this diameter is in the range suggested by ASTM C1701, Standard Test Method for Infiltration Rate of In Place Pervious Concrete, i.e., 300 mm. This research helped identify the practicable specimen size that could be utilized by researchers and practitioners to estimate the most reliable field infiltration rates through PC.@en

Due to exponential increase in urbanization, there is a huge demand for aggregates in industry for construction of buildings and roadways. This in turn has accelerated quarrying from large rock formations, causing significant impacts on the ecosystem. Thus, there is a need to explore and develop alternative materials to meet the goals of sustainable infrastructure. Therefore, the major objective of this research was to formulate a lifecycle assessment (LCA) framework to investigate the environmental benefits of utilizing excavated granulates (EG) found within the soil deposits at the Indian Institute of Technology Tirupati during earthwork activities as replacement for virgin aggregates in the base layers of pavement systems. To accomplish the objective, a cradleto-laid LCA approach was adopted as per ISO 14040 and ISO 14044. The LCA results showed that utilization of EG instead of virgin aggregates in pavement sub-base resulted in reduction of human health risk, global warming, and terrestrial eco-toxicity by 43.5%, 52%, and 68%, respectively. Sensitivity analysis showed that material production phase had the highest impact on environment for EG as well as virgin aggregates followed by material transportation and construction phases. The use of EG will not only alleviate the high environmental burdens associated with mining activities but also help conserve the depleting natural aggregate resources. Additionally, the use of EG in pavements will provide an alternative for disposal of these naturally occurring rock masses. It is envisioned that the outcomes obtained in this study will be used as a benchmark to initiate the process of utilizing EG in pavements. Furthermore, the systematic framework presented in this study will certainly help policymakers in the decision-making process and promote the development of similar LCA studies for site-specific conditions, specifically to create smart village ecosystems that call for utilization of local resources to create products that promote sustainable development.@en

This study provided a systematic lifecycle assessment (LCA) methodology that was used to quantify the total embodied energy and greenhouse gas (GHG) emissions involved in construction of a new pavement. Furthermore, a comparative LCA was performed to adjudge the benefits offered by pervious concrete pavement (PCP) over Portland cement concrete pavement (PCCP) for different mixing procedures, and distinct base layers. The system boundaries included the following phases of pavement LCA: raw material production, transportation, and pavement construction. The total embodied energy and GHG emissions were quantified for a functional unit of 1 km single lane road, 3.5 m wide, and 0.35 m thickness. The relative contribution of each component to energy consumption and GHG emissions was estimated and the variability of LCA model parameters was understood using sensitivity analysis. The results dictated that the total embodied energy and GHG emissions in PCP with aggregate base layer were reduced by up to 3% and 2.7%, respectively, compared to that of PCCP with similar configuration. Further, a capital cost analysis was conducted due to non-availability of maintenance and end-of-life data, which indicated that PCP is almost 1.21% costlier than PCCP for RMC mixing, and 4.13% cheaper for in-situ mixing. The conceptual approach developed in this study provided a generalized methodical framework that could be used to assess the environmental credibility of pavement systems for site-specific conditions.@en