Life cycle assessment of hot mix asphalt with recycled concrete aggregates for road pavements construction

In this study a comparative life cycle assessment (LCA) was conducted according to a ‘cradle-to-laid’ approach to evaluate the potential environmental impacts related to the use of recycled concrete aggregates (RCAs) as a partial replacement of coarse natural aggregates in the production of Hot Mix Asphalt (HMA). Specifically, three percentages of RCA replacements were analyzed: 15, 30 and 45%. Primary data collected mainly through surveys performed in Colombian contractors from the region of Barranquila were used to model the foreground system. The SimaPro 8.4.0 software was used for modelling the processes analyzed in the case study and all the life cycle inputs and outputs related to the functional unit were characterised during life cycle impact assessment (LCIA) phase into potential impacts according to the TRACI v.2.1 impact assessment methodology. The results of the case study showed that the mixtures incorporating 15 and 30% of RCA can be considered as eco-friendly alternatives to the conventional mixture (i.e. no RCA content), as both allow reductions in all impact categories scores. On the contrary, the mixture that contains 45% of RCA denoted a lower environmental performance than that of the conventional mixture

Experimental Evaluation of Modified Sulfur Concrete for Achieving Sustainability in Industry Applications

Portland cement concrete (PCC) has been the most widely used concrete in the construction industry. However, PCC has a short service life under some aggressive environments, leading to the need of costly repairs. The purpose of this research was to implement local materials to produce a modified sulfur concrete (MSC) with better performance in industrial applications. Several modified sulfur concrete mixtures were prepared using natural aggregates from the northern region of Colombia, and sulfur cement by combination of sulfur with a modifier, with the objective of achieving the best performance based on mechanical strength and chemical resistance. To achieve this purpose, an experimental program based on a k-factorial design was used to determine the optimal mix design based on the results of the compressive strength. The mixture presenting the best results was then examined further with standardized tests to determine its physical, mechanical, and chemical properties (compressive strength, abrasion resistance, bulk density, absorption, and chemical resistance). Final results showed that the sulfur concrete mixture is very resistant to chemical attack and an outstanding substitute for PCC. The results indicated that there is no significant loss in weight and no relevant variation in compressive strength after the specimens were immersed in sulfuric acid and sulfate solutions. In addition, similar results were obtained for the slabs located in chemicals plants whose conditions were assessed during a 60-day period of exposure

Comparative life cycle assessment of warm mix asphalt with recycled concrete aggregates: A Colombian case study

This paper presents the results of a comparative life cycle assessment undertaken to compare the potential environmental impacts associated with the use of Recycled Concrete Aggregate (RCA) as a partial replacement of natural aggregates in the production of Warm Mix Asphalt (WMA), with those of a conventional Hot Mix Asphalt (HMA). Laboratory testing results were used as inputs in a pavement design software with the purpose of designing several pavement structures with different percentages of RCA and according to the typical Colombian pavement design conditions. Primary data was collected from several companies in the northern region of Colombia. The SimaPro 8.4.0 software was used for modeling the processes analyzed in the case study and all the life cycle inputs and outputs related to the functional unit were characterized during the life cycle impact assessment (LCIA) phase into potential impacts according to the impact assessment methodology TRACI v.2.1. The LCIA results of the case study showed that the use of WMA with RCA as a replacement of coarse natural aggregates leads to a deterioration of the environmental profile of the pavement structures

Environmental performance evaluation of warm mix asphalt with recycled concrete aggregate for road pavements

A Life Cycle Assessment (LCA) was undertaken to compare the potential environmental impacts associated with the use of Recycled Concrete Aggregate (RCA) as a partial replacement of natural aggregates in the production of Warm Mix Asphalt (WMA), with those of a conventional Hot Mix Asphalt (HMA). The LCA was conducted according to the ‘cradle-to-laid’ approach, including four pavement LCA phases. Three percentages of RCA replacement for natural coarse aggregates in WMA were considered: 15, 30 and 45%. The results of laboratory tests were used as inputs in the design of pavement structures with different percentages of RCA for typical Colombian pavement design conditions. Primary data and SimaPro 8.4.0 software were used in modelling the processes analysed in the case study. All the life cycle inputs and outputs related to the functional unit were characterised according to the impact assessment methodology TRACI v.2.1. The results show that the potential environmental benefits arising from the combined effect of reducing the consumption of natural aggregates and reduced mixing temperature are offset by the reduced performance and the increased optimum asphalt content when incorporating RCA in WMA. The highest relative increase in the environmental impacts, at 29%, was observed in the Ecotoxicity impact category

Comparative Environmental Assessment of Rigid, Flexible, and Perpetual Pavements: A Case Study of Texas

Unlike conventional pavements with a service life of 20~30 years, perpetual pavements (PPs) are designed to have a 50-year service life without requiring major maintenance and rehabilitation (M&R) activities. In this way, PPs are more cost-effective than conventional rigid pavements (CRPs) and conventional flexible pavements (CFPs). Nonetheless, even though the economic and mechanical aspects of PPs have been widely studied and well documented, the literature is limited regarding the environmental assessment of PPs. Consequently, this research estimated the environmental burden associated with five pavement structures (one CRP, one CFP, and three PP structures) through the life-cycle assessment (LCA) methodology. Notably, the PaLATE computational tool was used to carry out the LCAs. The results indicated that for CFP, most of the environmental impacts are generated by the M&R activities. Otherwise, for CRP and PP structures, the most impact occurred during the initial construction stage. The study results also revealed that materials production is the sub-stage that most contributed to the generation of environmental detriments. Overall, this comparative case study concluded that the pavement alternative with the slightest environmental damage is the PP structure

Comparative Environmental Assessment of Rigid, Flexible, and Perpetual Pavements: A Case Study of Texas

Unlike conventional pavements with a service life of 20~30 years, perpetual pavements (PPs) are designed to have a 50-year service life without requiring major maintenance and rehabilitation (M&R) activities. In this way, PPs are more cost-effective than conventional rigid pavements (CRPs) and conventional flexible pavements (CFPs). Nonetheless, even though the economic and mechanical aspects of PPs have been widely studied and well documented, the literature is limited regarding the environmental assessment of PPs. Consequently, this research estimated the environmental burden associated with five pavement structures (one CRP, one CFP, and three PP structures) through the life-cycle assessment (LCA) methodology. Notably, the PaLATE computational tool was used to carry out the LCAs. The results indicated that for CFP, most of the environmental impacts are generated by the M&R activities. Otherwise, for CRP and PP structures, the most impact occurred during the initial construction stage. The study results also revealed that materials production is the sub-stage that most contributed to the generation of environmental detriments. Overall, this comparative case study concluded that the pavement alternative with the slightest environmental damage is the PP structure

Statistical Evaluation of the Material-Source Effect on the Ductility and Elastic Recovery (ER) of Plant-Mix Extracted Asphalt-Binders

This study was conducted to quantitatively and statistically evaluate the effects of material source on the ductility of asphalt-binders, measured in terms of the elastic recovery (ER) property. The ER data used in the study were excerpted from the Texas flexible pavements and overlays database, namely, the Texas Data Storage System (DSS), covering plant-mix extracted PG XX-22 asphalt-binders (i.e., rolling thin film oven (RTFO) residues) from 20 different sources and measured using the Ductilometer test at 10°C. The findings of the study indicated that material source has an impact on the ER property of asphalt-binders. Statistically significant differences were observed among some sources and suppliers that reported the same low-temperature asphalt-binder type/grade (i.e., PG XX-22). Overall, the study contributes to enriching the literature on the material-source effects on asphalt-binders’ ER properties, consistency, variability, and data quality. In particular, the study highlights the sensitivity nature of the asphalt-binder ER parameter to material-source effects

Statistical Evaluation of the Material-Source Effects on the DSR Rheological Properties of Plant-Mix Extracted Asphalt-Binders

The work presented in this paper was carried out to statistically evaluate and quantify the material-source effect on the asphalt-binder’s rheological properties using Analysis of Variance (ANOVA) and Tukey’s Honestly Significant Difference (Tukey´s HSD) test. The study focused on the Asphalt-Binders’ high-temperature rheological properties, namely, the G*, δ, G*/Sin(δ) and G*/(1 − (1/Tan(δ)Sin(δ))) parameters, measured using the Dynamic Shear Rheometer (DSR) device. The DSR data analyzed in the study were extracted from the Texas flexible pavements and overlays database, namely, the Texas Data Storage System (DSS), covering two Asphalt-Binders (ABs), performance grade (PG) 64-22 and PG 76-22 plant-mix extracted ABs that were treated as rolling thin film oven (RTFO) residue, and sourced from 14 different suppliers. The study findings substantiate that material-source has an effect on the high-temperature rheological properties of ABs. Additionally, it was also concluded that in as much as performance superiority and costs are crucial issues in deciding the AB source/provider, consistency and quality aspects cannot be disregarded. Therefore, material-source effects should be inclusively evaluated from both performance (rheological properties) and quality (consistence) standpoints as well as cost considerations when choosing a supplier. In general, the study contributes to the state-of-the-art enrichment on aspects of material-source effects on RTFO residue ABs’ high-temperature rheological properties, consistency, variability, and data quality