Search

The use of Lightweight Cellular Concrete (LCC) as a subbase alternative to typical flexible pavement subbase material in cold regions is gaining attention. Since a setback of using LCC is its high cement content, which is a significant source of carbon dioxide (CO2) emissions, it becomes imperative to consider this aspect when proposing LCC for pavement applications. This study evaluated the environmental impact of three densities (400, 475, and 600 kg/m³) of LCC produced with two methods (wet and dry mix) and compared to two types of unbound granular material (granular A and B) as flexible pavement subbase. The pavement performance was predicted using MEPDG and WESLEA software and compared with measured field responses as a basis for maintenance strategy. The Life Cycle Assessment (LCA) results showed that lower-density LCC pavements decreased environmental costs by reducing total life CO2 emissions by up to 16% and reducing environmental impact for Carbon monoxide, Sulphur dioxide, Nitrogen oxide, Particulate Matter (PM)2.5, PM10 and total PM compared to granular A and B pavements. As LCC density increased, more emissions occurred, showing the importance of density to emissions output. This research demonstrates the potential benefits of using LCC as an alternative subbase pavement material. [ABSTRACT FROM AUTHOR]

Permanent deformation, or rutting, is one of several critical distresses in flexible pavements. This paper introduced a novel experimental method, a penetration test, for asphalt mixtures to quantify the effects of glass fibre geogrids embedded in asphalt under repeated loading. It was found that the evolution of permanent deformation (εp) and its strain rate have three clearly identifiable stages. It was also observed that the presence of the geogrid increased the flow number and the number of cycles to failure significantly compared to control samples. Some of the current εp fitting models were found to be valid for deformation prediction under penetration. In addition, a new simple FN calculation method was also proposed based on strain rate and it showed consistent results. In particular, geogrid type "Grid10", which has smaller aperture size (12.7 mm) had slightly better reinforcement performance regarding the rutting resistance due to its larger contact area. Overall, the test and data analysis method presented in this study could be an important reference for future investigations on geosynthetic-reinforced pavement materials. [ABSTRACT FROM AUTHOR]

The objective of engineers to improve the long-term performance of road infrastructure in changing global climate has led to the development of alternate materials for pavement construction. Lightweight cellular concrete (LCC) is a viable option for colder climates where pavements undergo several freeze-thaw cycles each year, resulting in faster deterioration of pavements. This is due to LCCs' excellent freeze-thaw resistance, ease of placement, and potential sustainability benefits such as reduced use of virgin material and industrial by-products. However, there is a need to quantify these benefits and develop unified specifications for using LCC in the pavement structure. Therefore, this study examined the performance of flexible pavement sections that included a subbase layer, unbound granular materials for the control section, and three LCC densities (400, 475, and 600 kg/m3) for the LCC sections. Post-construction evaluation of pavement stiffness and roughness were evaluated using a Lightweight deflectometer and SurPro equipment. The results showed that LCC subbase thickness ≥ 250 mm produced over 22% smoother riding surfaces than unbound granular pavements while increasing pavement stiffness by up to 21%. Finally, this study recommends that LCC subbase thickness should not be thinner than 250 mm when using densities below 475 kg/m3 over weak subgrades. [ABSTRACT FROM AUTHOR]

• Organic intercalated LDHs and antioxidant were applied to modify asphalt. • The anti-aging mechanism of CA-LDHs/antioxidant composite modified asphalt was proposed. • There was a synergistic effect between antioxidant and LDHs in improving the aging resistance of modified asphalt. • The composite of antioxidant/CA-LDHs showed better improvement in the aging resistance of asphalt than single CA-LDHs. To improve the aging resistance of bitumen for the construction of durable flexible pavement, the composite of antioxidants and cinnamic acid intercalated layered double hydroxides (CA-LDHs) were applied to modify-four styrene–butadienestyrene (SBS) modified bitumens (SMBs) aiming at revealing the anti-aging mechanism of different modifiers according to the aging behaviors of SMBs which were evaluated by the physical and rheological properties, characteristic functional groups and chemical compositions of SMBs before and after thermal-oxidative and ultraviolet (UV) aging. The results show that antioxidants/CA-LDHs can simultaneously improve the thermal-oxidative and UV aging resistance of four kinds of SMBs. Compared with the composite of pentaerythritol tetrakis (3-(3,5-di- tert -butyl-4-hydroxyphenyl) propionate) (1010), tris (2,4-di- tert -butylphenyl) phosphite (1 6 8) and CA-LDHs, the composite of octadecyl-3-(3,5-di- tert -butyl-4-hydroxyphenyl)-propionate (1076), tris (2,4-di- tert -butylphenyl) phosphite (1 6 8) and CA-LDHs shows a better improvement effect on the anti-aging performance of SMB. LDHs can shield UV light and prevent oxygen from penetrating into SMB, and antioxidants can capture and decompose intermediate products generated during aging, these effects would restrain the oxidative aging. It is concluded that there is a synergistic effect between antioxidants and LDHs in improving the thermal-oxidative and UV aging resistance of SMBs. [ABSTRACT FROM AUTHOR]