A comprehensive review of warm mix asphalt mixtures-laboratory to field

In this research, a methodology was developed to optimize the design of Warm Mix Asphalt (WMA) with the inclusion of three recycled materials as partial replacement of natural aggregates (NAs), namely Crumb Rubber (CR), Reclaimed Asphalt Pavement (RAP), and Recycled Concrete Aggregate (RCA). The methodological proposal is composed of 4 sections denominated: (I) environmental module, (II) economic module, (III) decision-support module, and (IV) results report module. Initially, a Life Cycle Assessment (LCA) is carried out to quantify the environmental impacts associated with WMA production. Similarly, in the second module, a Life Cycle Costing (LCC) is performed to estimate the financial investment required by the process under evaluation. Meanwhile, a computational model based on genetic algorithms (GAs) is created in the decision-support module to execute multi-objective optimization (minimization of costs and contaminating potential). In the last module, the more accurate WMA designs are presented employing a Pareto front, ternary plot, composition pie chart, and statistical analysis of the influence of the CR, RAP, and RCA on the validation criteria. This study concludes that even under long hauling distances and huge prices, it is possible to design WMA with CR, RAP, and/or RCA additions that form sustainability benefits compared to conventional WMA. 

A multi-objective optimization based on genetic algorithms for the sustainable design of Warm Mix Asphalt (WMA)

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 GFRP-CW 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. 

Glass and carbon fiber reinforced polymer composite wastes in pervious concrete: Material characterization and lifecycle assessment

• Developed Pervious All-Road All-weather Multilayered pavement (PARAMpave). • Addressed the concern of inherent low strength of pervious concrete via PARAMpave. • Quantified the reduced environmental impacts of PARAMpave over concrete blocks. • PARAMpave were found to be economical alternatives to conventional paver blocks. 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. 

Engineering properties and lifecycle impacts of Pervious All-Road All-weather Multilayered pavement

Laboratory study on the suitability of nano-silica as a modifier for asphalt binders

Effect of the use of recycled asphalt pavement (RAP) aggregates on the performance of pervious paver blocks (PPB)

This study aims at examining the performance of asphalt mastics in the Linear Viscoelastic (LVE) domain incorporating three Indian and three Austrian fillers. The various physical, morphological, and chemical properties of the fillers were analyzed with the help of respective characterization tests. In addition to the particle size distribution curve and fineness modulus, a new parameter called Filler Grain Coefficient (FGC) has been introduced in this study to quantify the distribution of particles in the system. This paper also attempts to find a correlation between various physical parameters. There are two variables i.e., 
$$\left| {G^{*} } \right|_{\text{LVE}}$$

 and 
$$\left| {G^{*} } \right|_{\text{ratio}}$$

 in order to quantify the Linear Viscoelastic complex modulus. The effects of both volume and surface area of fillers have been manifested by three ratios denoted as V/FM, V/FGC, and V/RV. To compare the outcome of the study, the Strategic Highway Research Program Linear Viscoelastic strain criteria is also included, which examines the applicability of the criteria to the asphalt mastics. The research incorporates a wide range of fillers with variable properties, as confirmed by the test results. Filler parameters Rigden Voids and Filler Grain Coefficient were found to be strongly correlated with almost all physical properties. On the grounds of variation in LVEM with volume concentration of filler, the highest rank can be attributed to Red Mud and LimeStone, respectively, followed by other fillers with Marble Dust being the lowest. The reinforcing effect of fillers and higher surface area contributed to the exponential increase in 
$$\left| {G^{*} } \right|_{\text{LVE}}$$

, with an increase in volumetric concentration. The variation of both variables: 
$$\left| {G^{*} } \right|_{\text{LVE}}$$

 and 
$$\left| {G^{*} } \right|_{\text{ratio}}$$

, presented V/FM as the most worthy parameter, as it illustrated variation at different temperatures. The Linear Viscoelastic limits obtained from the study were relatively conservative compared to those from the SHRP study, this confirms the unsuitability of applying SHRP equations to the asphalt mastics. Moreover, the relationship instigated in the study can be used to reckon the LVE strain limit and to further analyse asphalt mastics.

Assessing the effect of fillers on LVE properties of asphalt mastics at intermediate temperatures

This study involves the quantification of fatigue damage in asphalt materials by introducing a new fatigue damage parameter denoted as the F parameter. One waste filler, i.e., red mud and an asphalt binder were chosen to blend the asphalt mastics at three filler contents of 10, 20, and 30% respectively with respect to the volume of binder and tested at temperatures of 5, 15, and 25 °C. The proposed parameter incorporates the effect of both peak shear stress as well as the failure strain, and hence, can better represent the fatigue damage. A lower value of F is recommended for a better fatigue resistant material. The F parameter was found increasing with the increment in filler content, which signifies higher degree of damage with a high level of stiffening. On the other hand, it consistently decreased with the increment in temperature. The behavior of the materials under the action of increasing shear strain was clearly justified by using the F parameter corresponding to different filler contents and the testing temperatures. In addition to that, the observations from the F parameter were also complemented by the fatigue diagrams. Hence, the proposed parameter is envisaged to be a promising fatigue damage indicator in future works.

Introduction of a New Parameter to Quantify the Fatigue Damage in Asphalt Mastics and Asphalt Binder

This study is an attempt to quantify the nonlinear rheological behavior of four different asphalt binders using linear amplitude sweep (LAS) test and large amplitude oscillatory shear (LAOS) test at intermediate temperatures (10 °C, 20 °C, and 30 °C) in unaged (UA) and short-term aged (STA) conditions. Additionally, the present study also relates the response of the asphalt binders under increasing strain amplitude, obtained from both test methods. LAS test results indicated improvement in the fatigue life of asphalt binders with an increase in temperature. The effect of ageing on fatigue life was found to be binder dependent. Lissajous–Bowditch (LB) plots and higher-order harmonic ratio $I_{3} /I_{1}$
 were found to be imperative analysis procedures to study the LAOS test results. The effect of instrument inertia at low strain and higher frequency, along with the deterioration of the binder at high strain amplitudes, led to distorted stress-strain LB curves, which resulted in ambiguous values of strain stiffening ratio $S$
 . It was found that $I_{3} /I_{1}$
 can be appreciably correlated with the fatigue life $N_{f}$
 obtained from LAS test using the relationship $N_{f} =0.2 \times ( \frac{I_{3}}{I_{1}} )^{-1.42}$
 . The relationship validated in the study is found to be independent of temperature, type of binder, and ageing condition.

Mohit Chaudhary

Papers

Effect of the use of recycled asphalt pavement (RAP) aggregates on the performance of pervious paver blocks (PPB)

Assessing the effect of fillers on LVE properties of asphalt mastics at intermediate temperatures

Introduction of a New Parameter to Quantify the Fatigue Damage in Asphalt Mastics and Asphalt Binder

Relating asphalt binders response to LAS and LAOS tests at intermediate temperatures

Influence of filler-binder ratio and temperature on the Linear Viscoelastic (LVE) characteristics of asphalt mastics