Paper by EAGLE from ASCP 6th 2021 Online
The Carbon nanotubes (CNTs) in a liquid additive when used in the design and construction of concrete, serve as nucleation sites during cement hydration to help create a denser, cement paste composition. The result is improved durability and strength. CNT technology remains young within Australia; various laboratory and field trials have completed. Trials have yielded increases >10mpa, equalling ~10% - 30% improvements in compressive strength gains as tested to AS1012.9 2014. Reducing the permeability of the concrete, the CNT dispersed additive reduces moisture, chemical and chloride ingress. One trial tested at 50% reduced permeability per Nordtest Method NT Build 443 1995-II. On an interstate highway project for Georgias Dept. of Transport, abrasion resistance and compressive strength were increased by more than 30% per ASTM C779, proc. C, and ASTM C39, respectively. CNT contributes to increased tensile and flexural strengths. A trafficable drainage run off area subjected to abrasive conditions, placed concrete drain sections with and without CNT additive in the concrete, a tensile strength increase of 25% and abrasion resistance of 40% resulted. After 36 months in service the CNT concrete showed no cracks or pitting vs. the control mix which cracked (>0.3mm) and was deeply pitted. CNTs have demonstrated the ability to eliminate or reduce use of wire mesh and macro fibres in on ground applications. CNTs in a secondary version of the liquid additive, provides sustainability opportunities by potentially reducing the carbon footprint with reduced GP cement use. Results with CNT technology will be detailed further in this paper.