Porous asphalt has been used for permeable pavement to improve safety of roadways and the effectiveness of storm water management. As a surface drainage layer with frequent exposure to water, this material is affected by moisture. In this study, dynamic modulus tests were performed on both moisture unconditioned and conditioned specimens to characterize viscoelastic properties of porous asphalt mixture. The dynamic modulus values of porous asphalt materials with air void content of 9.0% and 20.5% were investigated at dry condition and after specified moisture conditioning cycles. One cycle of moisture conditioning procedure included placing specimens in water tank at 60 °C for 24 h, and then in another water tank at 25 °C for additional 2 h. The results showed that porous asphalt mixture with lower air void content resulted in higher values of dynamic modulus, and these values of porous asphalt with air void content of 9.0% was about 1.5 to 3.0 times that of porous asphalt with air void content of 20.5%. Higher value of the first number of performance graded binder (average 7-day maximum pavement design temperature) seems to make the dynamic modulus values at high temperatures larger. After moisture conditioning, the dynamic modulus of porous asphalt mixture increased, overall, especially at low temperatures. The appropriated selection of asphalt binder, a weakening of asphalt due to moisture damage can be reduced.

Ensuring the durability of concrete pavements against chloride ingress is critical, yet the relationship between electrical resistivity and chloride penetration remains underexplored. This study evaluates the effectiveness of entrained air and fly ash in mitigating chloride ingress using an electrical resistivity model and surface resistivity tests. Concrete samples with varying entrained air contents (0% to 10%) and Class C or Class F fly ash underwent three-year ponding tests in temperature-controlled indoor water baths and outdoor CaCl₂-NaCl brine solutions. The results indicate that lower entrained air contents led to a more rapid increase in resistivity, with concrete mixes incorporating Class C fly ash exhibiting 1.5 times greater resistivity gains than those with Class F fly ash. Surface resistivity tests revealed that reaction factors were 67% higher in specimens with 3.5% entrained air compared to 10.0%, while decreasing by 57% and 41% in concrete mixes containing Class F and Class C fly ash, respectively, across all chloride concentrations. Using back-calculated environmental factors, corrosion initiation potential in concrete pavements was projected for exposure periods of up to 50 years. These findings provide insights for optimizing entrained air and fly ash formulations to enhance pavement performance and durability.

This study addresses the need for effective rejuvenators in asphalt concrete mixtures containing Vacuum Tower Bottom (VB) binder, a by-product of petroleum refining. We investigated the use of a softening rejuvenator, comprising Carnauba (5.5%), Soybean oil (3%), water (81%), surfactant (1.5%), and additive (3%) from a Korean refining company, to mitigate the brittleness of VB binder. Laboratory experiments were conducted to compare the performance of the modified binder with the original hardened binder. The results showed that adding the rejuvenator improved the properties of the VB binder. Optimal asphalt grades were achieved with a 2% content of the softening additive in the VB binder. The rejuvenator enhanced moisture resistance, leading to settlements comparable to the control asphalt. Settlements after 20,000 load repetitions were 11.49 mm for the modified mixture, which were slightly better than the control material at 12.44 mm. Moisture stripping points occurred at around 16,000 cycles for the modified mixture, while the control material experienced them at approximately 13,000 cycles. Under freeze-thaw cycles, the modified mixture exhibited enhanced durability compared to the control mixture. The control mixture experienced a significant increase in rutting value of approximately 59.7% (from 12.4 mm to 19.7 mm), while the modified mixture showed a relatively lower increase of approximately 37.4% (from 11.5 mm to 15.8 mm). Additionally, the modified VB mixture demonstrated approximately 7.8% higher dynamic modulus at lower temperatures, indicating improved mechanical properties. It also displayed superior fatigue crack resistance, with a fatigue life of 18,385 cycles compared to 15,775 cycles for the control asphalt. Field results confirmed that the VB asphalt mixture with the rejuvenator achieved comparable site compactness to the control mixture, indicating successful compaction performance. These findings highlight the rejuvenator’s efficacy in mitigating binder stiffening and restoring the original state of aged asphalt binders.

The preventive maintenance (PM) of asphalt pavements reduces life-cycle costs and minimizes resource consumption compared with reactive rehabilitation, yet its cost-effectiveness is highly sensitive to application timing. This study develops a data-driven framework for determining optimal PM timing on Korean expressways by integrating network-level pavement management system (PMS) deterioration modeling with life-cycle cost analysis (LCCA). Using 10-year PMS time-series data from approximately 2200 asphalt pavement sections (2012–2021), a nonlinear regression of the Highway Pavement Condition Index (HPCI) yielded an exponential deterioration model with exponent β = 1.87 (R² = 0.996), confirming accelerating deterioration beyond a critical service age. The HPCI inflection coincides with the Grade-2 boundary (3.5–4.0), where surface distress growth—dominated by linear cracking (91.3% of total SD)—also peaks. A LCCA across 44 scenarios demonstrated that PM applied immediately before this acceleration onset minimizes the 40-year net present value (NPV; discount rate 4.5%). The optimal first PM application time was estimated at 10.8 years (≈56% of the 19.3-year average service life), reducing the 40-year NPV by up to 7 million KRW per section relative to the milling and overlay baseline (up to 16 million KRW in absolute NPV terms for concrete overlay sections). These findings provide a quantitative, reproducible basis for PM timing decisions applicable to the approximately 4000 km of expressway pavement managed by Korea Expressway Corporation.