In August 2016, a return for the 1-year assessment revealed the...

In August 2016, a return for the 1-year assessment revealed the damage to the slab without the CNT additive to be progressing, while the test slab was uncracked and visibly in better condition. Figures 5 and 6 show the extent to which the reference slab was badly discoloured, and cracks had grown larger. The tire path from vehicles had abraded the texture the surface nearly smooth. The results the in-service field evaluation (and lab testing) confirmed the CNT additive’s ability to provide superior performance relative to GDOT’s section 504 specification.
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After approximately 18-months in-service, figure 7 shows the slab with the CNT additive developed a crack along the centreline of the lane in which it was placed. Under identical in-service conditions, the test slab performed for a period approximately 4.5 times longer than the reference slab before developing a crack. When combined, the improved strength and added resistance to abrasion and cracking was appealing to the Georgia DOT for full-depth slab replacements on their highways.

The Georgia Department of Transportation revised their standard project specification for full-depth slab replacements using the concrete mix design specified in section 504, to require the CNT additive under evaluation at either an 8.3 or 16.6 L/m3 dosage, providing the engineer with the option to reduce the cement by 15% at his/her own discretion based upon the severity of the application area."

Enhanced performance of concrete with use
of Carbon Nanotube Enriched liquid additive