EDE’s cost of MWCNT is ~US$79/kg (including the cost of surface modification of MWCNT to make it hydrophyllic). This figure can be calculated from the information provided by EDE: the ratio MWCNT/Cement= 0.5/99.5, the addition of EdenCrete into concrete= 4 gallons/cubic yard and the cost of 1 gallon of EdenCrete reportedly US$25. The addition of MWCNT into concrete is ~0.8kg/tonne. The content of MWCNT in EdenCrete by weight is ~8%. The cost of MWCNT in 1 tonne of concrete is ~US$59. Assuming that the price of 1 tonne of ordinary pavement concrete could be about US$100 (please note that a structural concrete is somewhat 3x more expansive than a pavement concrete), the addition of EdenCrete makes the concrete at least 60% dearer, at least, as the overall cost of EdenCrete enriched concrete would also include a difference between a ready made ordinary concrete supplied in concrete trucks from the concrete plant (which costs US$100/tonne) and the on-site made concrete from the on-site batched dry ingredients mixed with Edencrete. This operation could add another US$100 to the overall cost of the Edencrete enriched pavement concrete, but this operation is only theoretical, as it is not viable. Who would like to complicate a process of the roadwork that much, knowing that a percentage of road workers in the USA are just simply illiterate? To overcome this issue, EDE would have to build their own network of concrete plants or sell EdenCrete by force to the existing concrete plants, forcing them to produce Edencrete enriched concrete, as it is unlikely that Oldcastle who have 1900 concrete plant locations or Lafarge with 1000 locations would be interested in the deal. If they were, they would already be in it, as they have known the process of adding MWCNT into concrete for years. However their resistant stand could change soon with the cheap graphene hitting the road. Graphene could soon become much cheaper than MWCN, as it is easier to produce
https://www.chemaxon.com/blog/is-graphene-ending-the-promises-for-carbon-nanotubes/ .Graphene can be even made of cockroaches
http://pubs.acs.org/doi/abs/10.1021/nn202625c or produced cheaply by chemical exfoliation of mined graphite. XG Sciences can actually sell graphene nanoplatelets (5-8mm thick) at $40-50/kg for tonnage quantities and the price will drop much further soon, as it keeps dropping faster than the price of MWCNT, which currently can be purchased at about US$50.
http://www.graphenestakeholders.org/gsa-news/xg-sciences-graphene-nanoplatelets/ .This type of graphene can be turned into GO and then can be given a go as an ingredient of concrete at a fraction of price offered with MWCNT, while MWCNT could become obsolete. The Monash University’s patent (publication date Jul 2013), which many of my adversaries on this forum regard to be a bone of the intellectual property of EDE, is actually titled “Graphene oxide reinforced cement and concrete” and contains some unenthusiastic statements regarding CNT:
“With the concurrent benefits of high aspect ratio and excellent mechanical performance, CNTs have been found to improve the toughness and strength of cementitious matrix materials. However, the incorporation of CNTs in cement composites has proven to be rather complex and sometimes yields contrasting results. Several researchers have found that the addition of CNTs results in little change in strength or even a deterioration of the composite in some cases. The reasons for this are generally attributed to the poor dispersion of CNTs and weak bonding between the CNTs and the cement matrix. Owing to strong Van der Waal's attractive forces between particles, CNTs tend to form agglomerates or bundles which may become defect sites in the composites. Saez et al. [2] tested CNT/cement composite by nanoindentation measurements and found that the samples containing CNTs without dispersing agent had worse mechanical properties than the plain cement paste. A non- uniform distribution of CNT bundles within the matrix was also observed, which is responsible for the deterioration in the mechanical properties. In contrast, the mechanical properties improved with respect to the samples containing CNTs when dispersing agents were used.
Besides poor dispersion, another problem that limits the efficiency of CNTs in the cement matrix is the difficulty in achieving adequate CNT/matrix bonding. A CNT can be thought of as a graphene sheet that has been rolled up into a tube structure. The tube-shaped CNTs exhibit reduced interfacial contact area since the outermost CNT shields the tubes' internal surfaces from the matrix [14]. The lack of interfacial areas between CNTs and the cement matrix deteriorates CNT's reinforcing efficiency, even though CNTs exhibit excellent mechanical properties. A study by Cwirzen et al. [12] indicated that MWCNTs introduced as a water suspension with added surfactant admixture did not increase the compressive and flexiiral strength, even though good dispersion was obtained. One of the possible reasons is that the bonding between the MWCNTs and the cement matrix to be rather weak. As a result the MWCNTs are easily pulled from the matrix when subjected to tensile stresses”.
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