SBIR Phase II: Smart Two-Way Shape Memory Polymer Based Sealant

This Small Business Innovation Research Phase II project aims to provide an affordable sealant for sealing joints and cracks in cement concrete pavement, asphalt concrete pavement, bridge deck, etc. In transportation infrastructure, joints are intentionally constructed in order to allow movement of the structural elements due to linear thermal expansion/contraction when temperature rises/drops. Cracks are a common failure mode in pavement, and if not properly sealed, can cause water damage and rupture of the concrete. Sealing cracks and joints is a common practice to maintain or extend the service life of structural elements. Various types of sealants are currently used with an annual market value of about $6.1 billion. Unfortunately, many of these sealants fail to work properly and are ineffective in extending service life. In this project, a smart sealant will be developed that expands upon cooling and contracts upon heating, a thermal characteristic opposite to that of concrete. The product will address a significant problem in the industry arising from thermal movement of joined/cracked structural elements. It is expected that the product will have about 0.8% market share in 5 years helping with the need for longer lasting and more reliable infrastructure. The intellectual merit of this project lies in the development and validation of a smart sealant technology. The root cause for joint failure is that the thermal expansion characteristics of most sealants is similar to that of concrete, i.e., contraction upon cooling and expansion upon heating. This behavior is contrary to what is required of sealants in order to avoid thermally induced separation between the sealant and the concrete. Unfortunately, few materials can fulfill this requirement in a cost effective way while maintaining other desired physical properties (such as, deformability). This Phase II project will solve the century-long problem through the use of a two-way shape memory polymer (2W-SMP) based sealant that addresses the root cause. Building upon the feasibility study of the Phase I project, the Phase II project will focus on further improving the 2W-SMP based sealant for sealing joints or cracks in pavement, and validate the product through third-party lab-scale testing, and full-scale field-level verification in both hot and humid environment and extremely cold regions. Technical outcome will include lab-scale validation, field level performance and verification, and construction protocols for this new smart material, laying a solid foundation for adoption by home owners and transportation agencies.