Pavement Materials and Design

The real time field performance evaluation of flexible pavements constructed using mix with waste plastic coated aggregates as surfacing layer has been carried out and the results compared with that of the control section. Laboratory studies conducted on semi Dense Bituminous Concrete (SDBC), Bituminous Concrete (BC) and Dense Bituminous Macadam (DBM) show that the Marshall Stability value of bituminous mixes increase by 1.5 to 2 times by using Plastic Coated Aggregates. Also bitumen can be reduced by more than 10% by weight. Periodical performance evaluation conducted on test stretches indicated better functional performance. Better strength parameters and road condition indicates increase in life of pavement and delayed and slow deterioration. Utilization of waste plastic on a massive scale will eliminate the pollution caused due to land filling or incineration.

h i g h l i g h t s Mechanical properties of RCCP slightly decreased as a result of adding waste sand. Adding nano SiO 2 improved the mechanical properties of RCCP. The optimum content of Nano SiO 2 for RCCP was determined. Increasing the waste materials' content led to an increase in skid resistance. The mixes containing glass waste showed the highest abrasion resistance. a b s t r a c t This study deals with the use of waste materials as replacement of fine aggregate in roller-compacted concrete pavement (RCCP). To achieve this, waste ceramic, waste concrete, and waste glass were initially crushed and mixed and then replaced natural fine aggregate at varying amounts in RCCP. Furthermore, to mitigate the probable negative effects of waste aggregates and also to improve the mechanical properties of cement paste, nano SiO 2 was employed in the mixes design. After preparing the mixes, Vebe time, com-pressive strength, splitting tensile strength, water absorption, abrasion resistance, and skid resistance were measured. The results show that more than 40% of sand replacement with waste materials could have a negative effect on the properties of RCCPs. However, this impact is negligible up to 10% of waste material proportions. The compressive strength of the mixes containing waste materials was lower than that of the control mix, except for the sample containing 10% ceramic waste. In terms of water absorption, mixes with waste materials had higher water absorption than the control mix. Besides, abrasion somewhat increased as a result of adding waste materials, except for the samples containing 10% glass and 10% ceramic wastes that showed a slight decrease. Moreover, mixes with waste materials had higher skid resistance than the control mix. Overall, waste ceramic mixes showed better mechanical properties and waste glass mixes had better performance in terms of water absorption. In addition, using nano SiO 2 leads to improve the mechanical properties of the RCCP; the optimum content of nano SiO 2 has determined to be 0.7% of cement weight.

Rejuvenators are used to restore the properties of reclaimed asphalt pavement (RAP) binders through readjusting the balance between the asphaltene and maltene fractions. To properly understand the effect of rejuvenators, it is important to analyze the chemical changes in the rejuvenated binders and to relate these changes to the rheological properties of the binders. In this study, RAP binders were blended with a bio-based and an aromatic extract petroleum-based rejuvenator additive. Chemical and thermal techniques, such as differential scanning calorimetry (DSC), attenuated total reflection Fourier transform infrared (FTIR) spectroscopy, and saturate, aromatic, resin, and asphaltene determinator (SAR-AD) were used to analyze the control and rejuvenated RAP binders. Glass transition temperatures were obtained using DSC and correlated with rheological measurements using a dynamic shear rheometer (DSR) and a 4 mm plate geometry. From FTIR results, the evolution of the carbonyl and sulfoxide indices with aging were determined and correlated with the complex shear modulus DSR measurements at different aging stages. The SAR-AD analysis was used to determine the changes in the asphalt fractions with the addition of the rejuvenators. Temperature−frequency DSR sweeps and bending beam rheometer testing were conducted, and master curves were constructed for the different binders. From these master curves, the effect of the different rejuvenators on the crossover temperature, glass-transition temperature, and intermediate region temperature range (T IR) was determined.

Durability of asphalt pavements is related to choosing proper materials. Fillers as the smallest particles of stone materials, and one of the most important parts of asphalt mixtures, exert pivotal effects on the performance of asphalt mixtures, by filling empty spaces and because of their softness, surface features and chemical compounds. Rice husk ash is one of the waste products of burning rice husk in powerhouses that is accounted as biomass. Recently, a good many of investigations have shown that rice husk ash, as a high quality pozzolan, can be properly replaced of common aggregates. In this study rice husk ash was used as filler in hot mix asphalt, and the result mixtures' mechanical properties was compared with ordinary mixtures whose filler was stone powder. Asphalt mixture samples with two different aggregate graded, and 0, 25, 50, 75 and 100 percent of rice husk ash which were the substitution of stone powder content, were made and the effects of using rice husk ash on the moisture sensitivity, resilience modulus, rutting and dynamic creep of asphalt mixtures were investigated. The results demonstrated that increase of using rice husk ash as the replacement of prevalent fillers in hot mix asphalts, noticeably improves their performance; however, because of excessive stiffness created by rice husk ash, it's better to use it in optimized percentage. Accordingly, statistical analysis of the tests' results leads to presenting an optimized model for the content of Rice Husk Ash to be used in hot mix asphalt. Finally, Rice Husk Ash content were suggested 26% for graded number 4 and 48% for graded number 5 as replacements for stone powder filler.

h i g h l i g h t s Mechanical properties of RCCP slightly decreased as a result of adding waste sand. Adding nano SiO 2 improved the mechanical properties of RCCP. The optimum content of Nano SiO 2 for RCCP was determined. Increasing the waste materials' content led to an increase in skid resistance. The mixes containing glass waste showed the highest abrasion resistance. a b s t r a c t This study deals with the use of waste materials as replacement of fine aggregate in roller-compacted concrete pavement (RCCP). To achieve this, waste ceramic, waste concrete, and waste glass were initially crushed and mixed and then replaced natural fine aggregate at varying amounts in RCCP. Furthermore, to mitigate the probable negative effects of waste aggregates and also to improve the mechanical properties of cement paste, nano SiO 2 was employed in the mixes design. After preparing the mixes, Vebe time, com-pressive strength, splitting tensile strength, water absorption, abrasion resistance, and skid resistance were measured. The results show that more than 40% of sand replacement with waste materials could have a negative effect on the properties of RCCPs. However, this impact is negligible up to 10% of waste material proportions. The compressive strength of the mixes containing waste materials was lower than that of the control mix, except for the sample containing 10% ceramic waste. In terms of water absorption, mixes with waste materials had higher water absorption than the control mix. Besides, abrasion somewhat increased as a result of adding waste materials, except for the samples containing 10% glass and 10% ceramic wastes that showed a slight decrease. Moreover, mixes with waste materials had higher skid resistance than the control mix. Overall, waste ceramic mixes showed better mechanical properties and waste glass mixes had better performance in terms of water absorption. In addition, using nano SiO 2 leads to improve the mechanical properties of the RCCP; the optimum content of nano SiO 2 has determined to be 0.7% of cement weight.

Numerous distresses in pavement structures on chemically stabilized expansive soils have raised considerable debate regarding the long-term performance of lime-stabilized subgrades. Therefore, this paper examines the effects of continuous leaching on the durability of lime- and waste ceramic dust (WCD)-stabilized expansive subgrades. The tests were performed with different percentages of quicklime (3.5, 4.5, 5 and 10%), while the combined effects of lime and WCD were evaluated by adding 1.5% of WCD to the mixtures containing 3.5 and 4.5% lime. Geotechnical tests such as Atterberg limits, compaction and California bearing ratio (CBR), in addition to microstructural and leachate analyses, were used to evaluate the engineering properties of the stabilized soils. The CBR result shows that early strength development occurred in the soils mixed with lime and WCD. However, at longer curing periods, the beneficial effect of lime on the engineering properties of the soil increased with an increase in lime content. Results of the leaching tests show considerable changes in the physicochemical properties of the soil mixtures, while the estimated service life of the stabilized soils increased from 3.4 to 9.2 years, as lime content increased from 3.5 to 10%. Microstructural analysis results reveal that the flocculated nature of the soil fabric and the density of the fibrous cementitious compounds increased with an increase in lime content. This study clearly indicates that electrical conductivity, pH and pore-water cation concentrations can be used in combination with geotechnical tests, to correctly evaluate the durability of lime- and lime-WCD-stabilized expansive soils.

Rejuvenators are used to restore the properties of reclaimed asphalt pavement (RAP) binders through readjusting the balance between the asphaltenes and maltenes fractions. To properly understand the effect of rejuvenators, it is important to analyze the chemical changes in the rejuvenated binders and to relate these changes to the rheological properties of the binders. In this study, RAP binders were blended with a bio-based and an aromatic extract petroleum-based rejuvenator additive. Chemical and thermal techniques such as differential scanning calorimetry (DSC), attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy and saturates, aromatics, resins, and Asphaltene Determinator (SAR-ADTM) were used to analyze the control and rejuvenated RAP binders. Glass transition temperatures were obtained using DSC and correlated with rheological measurements using a dynamic shear rheometer (DSR) and a 4-mm plate geometry. From FTIR results, the evolution of the carbonyl and sulfoxide indices with aging were determined and correlated with the complex shear modulus DSR measurements at different aging stages. The SAR-AD analysis was used to determine the changes in the asphalt fractions with the addition of the rejuvenators. Temperature-frequency DSR sweeps and bending beam rheometer (BBR) testing were conducted, and master curves were constructed for the different binders. From these master curves, the effect of the different rejuvenators on the cross-over temperature, glass-transition temperature, and the intermediate region temperature range (TIR) was determined.