Evaluation of Reclaimed Asphalt Mixtures Modified by Nanoclay Powder on Moisture Damage

Recycling asphalt is a significant stage in pavement industry, yet it can be unfavorable to the durability of the recycled mix due to the loss of binder charachteristics, thus the mixture will be weaker to the external factors like moisture. This study aims to evaluate the influence of nanoclay montmorillonite k10 powder (MMT) on Marshall’s characteristics and moisture resistance in Reclaimed Asphalt Pavement (RAP) mixtures. Three percentages of rejuvenated RAP were used, 30%, 40%, and 50% of the total mixture, these percentages were modified with 0%, 1%, 3%, and 5% nanoclay (MMT) of the neat binder’s weight. Asphalt Cement AC(85-100) was used to rejuvenate the RAP. The Marshall test was conducted on modified RAP to detect the effect on the Marshall stability and flow and air void, indirect tensile strength tests (ITS) were also conducted before and after nanoclay powder addition to compare and assess the resistance of moisture to rejuvenated RAP mixtures. The results of the laboratory tests have shown that the use of 5% nanoclay in the regenerated RAP mixes offers superior performance than without it, where it enhanced stability by 15%, reduced flow by 14.3%, and increased moisture damage resistance by 3.66% all for 50% RAP mixtures.

SUPERPAVE design mixture performance evaluation using Epolene modifier for cold semi-arid climatic region of Saudi Arabia

Purpose: To evaluate the superpave design performance using Epolene (EE-2) as modifier, since SUPERPAVE design is a modified and sophisticated aspect as compared to previous mix design for asphalt mixtures. This is primarily due to the fact that superpave design mix also takes into consideration properties of materials beside asphalt. Design/methodology/approach: This study was conducted using Epolene (EE-2) as modifier in order to evaluate the performance of SUPERPAVE suitability for construction of roads in Alfaraa campus (King Khalid University) Abha, in Asir Province of Saudi Arabia. Glow number test, dynamic modulus test and indirect tensile strength test were conducted to evaluate the performance of EE-2 modifier against the control mixture. Findings: The mixture modified with EE-2 gave better performance in terms of temperature-based performance and resistance to moisture damage. Also, larger values of E*/sinφ were obtained for EE-2 modified mixture at various loading frequencies and temperature in comparison to control mixture. Research limitations/implications: The Epolene modifier successfully enhances and improves the SUPERPAVE mixture performance. Further studies are required to evaluate the performance of EE-2 modifier at much lower temperature ranges. Practical implications: The results of the study allow us to recommend the investigated asphalt mixture for applied for the construction of roads in the Alfaraa (new campus of King Khalid University), Abha, Asir province, Saudi Arabia. Originality/value: A modified asphalt mixture has been proposed that has better performance at higher and lower temperatures. The developed asphalt mixture is more resistant to moisture damage than the compared to control mixture.

Experimental Investigation of Moisture Sensitivity and Damage Evolution of Porous Asphalt Mixtures

Porous asphalt (PA) mixtures are designed with a high air void (AV) (i.e., 18~22%) content allowing rainwater to infiltrate into their internal structures. Therefore, PA mixtures are more sensitive to moisture damage than traditional densely graded asphalt mixtures. However, the moisture damage evolution of PA mixtures is still unclear. The objective of this study was to investigate the moisture damage evolution and durability damage evolution of PA mixtures. The indirect tensile test (ITT), ITT fatigue test, and Cantabro loss test were used to evaluate the moisture sensitivity and durability of PA mixtures, and a staged ITT fatigue test was developed to investigate the damage evolutions under dry and wet conditions. Indirect tensile strength (ITS), fatigue life, indirect tensile resilience modulus (E), and durability decreased with the increment of moisture damage and loading cycles. The fatigue life is more sensitive to the moisture damage. The largest decrements in ITS and E were found in the first 3000 loading cycles, and PA mixtures tended to fail when the decrement exceeded 60%. Damage factors based on the ITS and E are proposed to predict the loading history of PA mixtures. The durability damage evolution and damage factors could fit an exponential model under dry conditions. Moisture had a significant influence and an acceleration function on the moisture damage evolution and durability damage evolution of PA mixtures.

Multiple Chemical Sensitivity in Patients Exposed to Moisture Damage at Work and in General Working-Age Population—The SAMDAW Study

A considerable proportion of patients having respiratory tract or voice symptoms associated with workplace moisture damage (MD) could have multiple chemical sensitivity (MCS). MCS is characterized by symptoms of different organ systems in association with low-level chemical exposure. The objective of this study was to assess the prevalence of MCS among patients referred to secondary health care because of respiratory or voice symptoms associated with workplace MD compared to the general working-age population. Using three subscales of the QEESI© questionnaire, we assessed MCS in the study patients and 1500 controls in the same district randomly selected from the Finnish Population Information System. Study patients had significantly more often high scores in chemical intolerance (39% vs. 23%, p = 0.001), symptom severity (60% vs. 27%, p < 0.001), and life impact subscales (53% vs. 20%, p < 0.001). Asthma, chronic rhinosinusitis, laryngeal problems, and atopy were not associated with the presence of MCS. MCS is common among patients referred to secondary health care with respiratory tract and/or voice symptoms associated with workplace MD, and it considerably affects their everyday life. MCS should be considered as a possible explanatory factor for MD-associated symptoms.

Effect of Aging and Moisture Damage on Fatigue Cracking Properties in Asphalt Mixtures

Recently, damage to asphalt pavements in South Korea has increased because of direct and indirect factors caused by abnormal climatic changes, such as torrential rains, prolonged heatwaves in summer, and heavy snowfall in winter. Additionally, the use of medium and heavy vehicles is also a contributing factor. Therefore, an experimental procedure to study the moisture damage and fracture properties of asphalt pavements considering the recent changes in precipitation properties, deterioration of road pavement, and traffic conditions in South Korea was developed in this study. Additionally, changes in material properties according to the indoor aging process and fatigue crack resistance were evaluated for hot mix and warm mix asphalt mixtures of the same grade and different initial production and construction temperatures. To evaluate the effect of aging and moisture damage on fatigue cracking, the experimental coefficient values of the predictive model were calculated for each condition. It was observed that the material properties of hot mix asphalt mixtures changed with an increase in aging and moisture damage. The service life of the pavement was reduced by approximately 40–80% owing to moisture damage, whereas aging had a greater effect on fatigue life as the service life increased.

Using a Random Forest Model to Predict the Location of Potential Damage on Asphalt Pavement

Potential damage, eventually demonstrated as moisture damage on inner and in-situ road structures, is the most complex problem to predict, which costs lots of money, time, and natural resources for maintenance and even leads to safety problems. Traditional linear regression analysis cannot fit well with this multi-factor task in such in-field circumstances. Random Forest (RF) is a progressive nonlinear algorithm, which can combine all relative factors to gain accurate prediction and good explanation. In this study, an RF model is constructed for the prediction of potential damage. In addition, relative variable importance is analyzed to obtain the correlations between factors and potential damage separately. The results show that, through the optimization, the model achieved a good average accuracy of 83.33%. Finally, the controlling method for moisture damage is provided by combining the traditional analysis method and the RF model. In a word, RF is a prospective method in predictions and data mining for highway engineering. Trained with effective data, it can be multifunctional and powerful to solve hard problems.