Evaluation of recycled asphalt pavement in Colombia

Reclaimed asphalt pavements are obtained from existing pavements through recovery techniques and are used for new asphalt mixtures production with the inclusion of virgin aggregates and asphalt cement, constituting environmentally friendly mixtures at a lower total cost, by requiring fewer quantities of new materials. This research, unlike the studies found on the subject, focuses on the study of reclaimed asphalt pavement by analyzing its granulometric distribution and asphalt cement content. For this purpose, representative reclaimed asphalt pavement samples were taken from four Colombia cities, to verify their heterogeneity. The obtained reclaimed asphalt pavement was analyzed in the laboratory, to obtain the material granulometric distribution, through extraction and asphalt content tests, following Colombian regulations from the “Instituto Nacional de Vías”. The results show that the granulometry of all cities has a central tendency (average) that moves towards an upper limit in the 2 mm particles. When analyzing the granulometry separately of the four cities, it is observed that they present a different trend in their granulometry, which shows their heterogeneity. The asphalt cement content presented values between 4.0% and 5.0%.

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.

Resistance under Marshall monotonic load for asphalt concrete mixtures

The dense hot MDC-19 type asphalt mixes are considered, by the “Instituto Nacional de Vías” in Colombia, as continuous grading asphalt mixes (asphalt concrete). These constitute most of the surface course, in the structures of in-service pavements, being the object of study and research in different projects to ensure their durability. In the present investigation, unlike other investigations, the mechanical behavior under Marshall monotonic load was studied in the laboratory between MDC-19 dense type asphalt mixtures, comparing plant-produced and laboratory-produced asphalt mixtures. To carry out this process, samples of uncompacted asphalt mixtures were taken, produced in four fixed plants, with which Marshall-type briquettes were compacted. Likewise, samples of mineral aggregates and asphalt cement were obtained from the same plants, which constitute the mixtures raw material produced there. With these materials, briquettes with the same characteristics were mixed and compacted. Subsequently, the resistance under Marshall monotonic load was determined on the briquettes manufactured in plant and laboratory. The optimal asphalt cement content was compared between plant and laboratory- produced mixtures. An increase in Marshall Stability was found in the briquettes made with plant-produced mixtures, while these required a greater amount of asphalt cement for their production.

Materials Approach to Improving Asphalt Pavement Longitudinal Joint Performance

Many states are looking for methods to improve longitudinal joint performance of their asphalt pavements, since these joints often fail before the rest of the surface. With their inherently lower density, longitudinal joints fail by cracking, raveling, and potholing because of the intrusion of air and water. Because of their longitudinal joint issues, and after trying several less-than-successful traditional solutions, Illinois Department of Transportation (IDOT) developed a concept to seal the longitudinal joint region, but from the bottom up. Test sections were constructed in 2001 through 2003 to determine how a newly developed material, called longitudinal joint sealant (LJS), would improve joint performance. LJS is a highly polymer-modified asphalt cement with fillers and is placed at the location of a longitudinal joint before paving. As mix is paved over it, the LJS melts and migrates up into voids in the low-density mix, making the mix impermeable to moisture while sealing the longitudinal joint itself. The IDOT test pavements were evaluated after 12 years and found to have longitudinal joints that exhibited significantly better performance than the control joint sections and were in similar or better condition than the rest of the pavement. Laboratory testing of cores showed decreased permeability and increased crack resistance of mix near joints with LJS as compared with similar mix without LJS. The life extension of the joint area is approximately 3–5 years, and the benefit is calculated to be three to five times the initial cost.

Predicting a Model for Modified Asphalt Cement Rutting Parameters

This paper aims to investigate the relationship between the Superpave rutting parameter of asphalt (G﹡/sin δ) by conducting Dynamic Shear Rheometer (DSR) tests with the rut depth values obtained by the wheel track device. The twenty asphalt mixtures have been prepared with twenty types of unmodified asphalts and Polymer-Modified Binders (PMBs). SBS was used to produce PMBs. The twenty base and modified asphalts have been used to prepare asphalt paving mixtures required to conduct wheel track tests. The predicted model of asphalt mixtures rut depth related to asphalt rutting parameter (G﹡/sin δ) values has been founded. Besides, the minimum limits of (G﹡/sin δ) of aged asphalt have been gotten as 3.25 kPa for Iraqi asphalt cement.