Innovative Materials for America's Growth and Infrastructure Newly Expanded Act of 2018 or the IMAGINE Act This bill directs the National Institute of Standards and Technology to establish an Interagency Innovative Materials Standards Task Force to coordinate and improve, with respect to infrastructure construction, retrofitting, rehabilitation, and other improvements: (1) federal testing standards, (2) federal design and use guidelines, and (3) other applicable standards. The task force shall collaborate with certain nonfederal entities to: (1) identify and carry out appropriate research, testing methods, and processes relating to the development and use of innovative materials; (2) develop new methods and processes relating to the development and use of innovative materials; and (3) contribute to the development of standards and guidelines for the use of innovative materials and approaches in civil infrastructure projects. The term "innovative material," with respect to an infrastructure project, includes high performance asphalt mixtures and concrete formulations, geosynthetic materials, advanced alloys and metals, reinforced polymer composites, including any coating or other corrosion prevention method used in conjunction with those materials, advanced polymers, and any other material or aggregate materials, as determined by the appropriate agency or department head. The Department of Transportation shall carry out a program to enhance the development of innovative materials in the United States. The Federal Highway Administration shall establish the Innovative Bridge Program to provide grants for coastal and rural infrastructure bridge projects. The Environmental Protection Agency shall establish the Water Infrastructure Innovation Program to provide grants for the design and installation of water infrastructure projects.