Innovative Materials for America's Growth and Infrastructure Newly Expanded Act of 2021 or the IMAGINE Act This bill encourages the use of innovative construction materials and techniques to accelerate the deployment, extend the service life, improve the performance, and reduce the cost of domestic transportation and water infrastructure projects. Among other things, the bill establishes an Interagency Innovative Materials Standards Task Force to assess existing standards and test methods for the use of innovative materials in infrastructure, identify key barriers in the standards area that inhibit broader market adoption, and develop new methods and protocols to better evaluate innovative materials; requires the Department of Transportation to enhance the development of innovative materials in the United States by providing awards to entities for establishing and operating new innovative material innovation hubs; directs the Federal Highway Administration to provide grants to states' departments of transportation, tribal governments, public toll authorities, and units of local government for coastal or rural infrastructure bridge projects and value engineering projects to enhance the performance of bridges through the use of innovative materials; and provides grants for the design and installation of water infrastructure projects.