Shengwei Sun

Sensing Mechanism of Self-Monitoring CNT Cementitious Composite

Owing to its outstanding sensing properties, mechanical properties, and durability, self-monitoring carbon nanotube (CNT) cementitious composite can serve as an intrinsic smart sensor for structural health monitoring and traffic detection. However, it is not clear at present what the origin of the sensing property of the self-monitoring CNT cementitious composite is. This paper discusses the nature of the sensing property of the composite measured with dc and ac circuits based on a commonly used conductive model of CNT cementitious composite and reveals the origin of the sensing property of the composite through experiments. Experimental results indicate that the sensing property of the composite mainly results from the change in contact resistance between adjacent CNTs under external force or deformation.

Mechanical and Damping Properties of Wood Plastic Composite Modified by Ground Waste Rubber Tire

Recycled WPC product using in construction industry occasionally falls short of expectation owing to lack of sufficient ductility and damping capacity, ground waste rubber tire (WTR) with substantial elasticity can be a proper candidate to meet the gap when adding appropriately. Here, WTR after alkali activation was blended in waste wood flour (WWF) treated with compatibilizer, the mixture after oven-dried was subsequently filled into thermoplastic recycled polyethylene (RPE) or polypropylene (RPP) base (WTR/WPC) through hot-press molding process. Mechanical properties (tensile strength ft, flexural strength fb, impact strength fa) of RPE-based and RPP-based WTR/WPC strips with 4 different WTR fractions were characterized. Its damping properties (loss factor β) were measured and identified by ultrasonic agitation and half-power bandwidth identification method, respectively. The coarse WTR has balanced but stable effect on the improvement of ft, fb, fa, and β of WTR/WPC with rigid RPP base than that with flexible RPE, which attributes to the synthetic effects of good deformation capacity of coarse WTR themselves, strong bridging capacity of WWF, and sufficient stick-slip intercalation between WWF or WTR and rigid RPP. The ft, fb and fa, β with 5% coarse WTR of RPP-based WTR/WPC reaches 12.32 MPa, 15.74 MPa; 2.58 MPa and 0.0853, respectively.

Nano carbon material–filled cementitious composites: Fabrication, properties, and application

Abstract Advances in nanotechnology have opened up a wide range of opportunities for engineering properties of cementitious materials using nanoscale reinforcements. Development of this new class of cementitious composites has resulted in extensive academic and industrial research regarding the processing, characterization, and modeling of these materials. Nano materials, especially nano carbon materials (NCMs) including carbon nanofibers, carbon nanotubes, and nano graphite platelets, were found to be able to improve the mechanical property, durability, and functional properties of cementitious materials due to their excellent intrinsic properties and composition effects. This chapter introduces advances in NCM-filled cementitious composites with an aim at high-performance and multifunctional properties for structural applications. Key issues in research of NCM-filled cementitious composites (e.g., fabrication, properties, and mechanism) are addressed, along with challenges to add the reinforcing effect of NCMs to conventional cementitious composites and infrastructures made of them.