Lignin-Engineered Self-Sensing Composites: A Materials Framework for Sustainable Buildings

Abstract

Due to the construction sector’s high contribution to embodied carbon, interest exists in utilizing bio-based materials as an alternative to conventional construction materials. NFCs containing cellulosic fibers like flax, hemp, jute, and kenaf have favorable properties relative to conventional construction materials, but their use in housing construction has been limited both by the adhesion issues between the fibers and conventional matrices, as well as due to a lack of methods for monitoring the condition of NFCs after they are constructed. One framework for addressing these issues utilizes technical lignin, a byproduct of the pulp and biorefinery industries, to create matrices for NFCs, as well as to produce carbon-based layers that are conductive and act as strain sensors. These strain sensors can be utilized in conjunction with fiber-optic, mechanoelectrical, and wireless sensors that employ low amounts of power to monitor the NFCs after they are constructed. By drawing on the results of several different recent studies that have employed these techniques, such as the study that found that using lignin-based resins increased the flexural strength of jute fiber composites by 69.7% and the flexural modulus by 291.7%, another that found that treating hemp/cement composites with alkyl-ketene dimers resulted in 28% higher compressive and flexural strength, and yet another that found that using a contactless mechanoelectrical method to monitor the fatigue of flax/epoxy composites without embedded sensors is effective, it is possible to establish that each of these techniques can be separately applied to natural fiber composites. However, the combined application of these techniques to the same class of composite material has not yet been observed in any published studies. Furthermore, while it is possible to create a comparison of the performance and life-cycle of natural fiber composites to conventional building envelope materials in aspects not yet covered by the published research, it is also possible to propose a method for integrating these different techniques into building components like wall panels, studs, and roof sheathing. Finally, each of the techniques can be evaluated in relation to their potential barriers to widespread deployment, and a suggested roadmap for testing these different techniques in combination with one another can be proposed.