Development of Nanomaterials Additives to Improve Resistance to Moisture Damage in Hot Mix Asphalt (HMA)

Moisture is a key factor that contributes to the deterioration of asphalt concrete pavements. Moisture often results in premature failure of asphalt pavements in the form of isolated distress caused by debonding of the asphalt film from the aggregate surface or early rutting/fatigue cracking due to reduced mix strength. The specific objectives of the proposed research are to: 1) evaluate the performance of innovative types of surface coated nanoclays as modifiers for reducing moisture sensitivity of hot mix asphalt; 2) conduct a cost analysis to evaluate the feasibility of using nanoclays in large-scale applications for reducing moisture sensitivity of hot mix asphalt; and 3) conduct multi-criteria decision analysis to compare the performance of the nanoclays developed in this research to hydrated lime, a commonly used modifier for reducing moisture sensitivity of hot mix asphalt. The research consists of four different tasks, 1) aggregate and binder testing and characterization, 2) mix design, 3) testing moisture resistance with the addition of the nanoclays and compare the results to negative control (hot mix asphalt with no nanoclay) and positive controls (hot mix asphalt modified with hydrated lime), and 4) multi-decision criteria analysis to systematically evaluate alternative additives for enhancing moisture resistance of hot mix asphalt.

Principal Investigator: 

Amro El Badawy

PI Contact Information:

Cal Poly San Luis Obispo


June 2021 to May 2022

Impacts/Benefits of Implementation: 

Departments of Transportation throughout the US invest hundreds of millions of taxpayers’ dollars on maintaining and managing the pavement infrastructures. For example, in California only, Caltrans invests between $500 million and $600 million annually for the maintenance and rehabilitation of approximately 50,000 lane-miles of paved highways. Finding a cost-effective modifier will drastically increase the service life of the pavement and consequently, the cost will be significantly less. If proves successful, the proposed technology will save DOTs millions of dollars of annual cost for maintenance and rehabilitation of pavement. In addition, the multi-criteria decision analysis to be conducted herein will help Caltrans and other DOTs make informed decisions about alternative modifiers for improving moisture resistance of HMA.

The proposed research will involve multi-disciplinary collaboration with partners from academia (e.g., chemistry and materials engineering departments will assist with synthesis and characterization of nanomaterials), State DOTs (e.g., Caltrans will provide data and testing materials), and industry (e.g., potential partners will help commercialize the technology to be developed by this research). The City and County Pavement Improvement Center (CCPIC) and the California Department of Transportation (Caltrans) will collaborate on this project.

Project Number: