Electrically conductive high-carbon concrete (HCC) is being developed and could potentially be used for many new technological advances. Carbon from high-carbon fly ash and spent carbon sorbent—both byproducts of coal combustion in modern power plants—make HCC a conductor. Initial HCC applications have included low-cost grounding for lightning-vulnerable structures, but a much wider range of use is envisioned, including electrical shielding, self-deicing bridges, induction-charging of electric vehicles, and pavements that function as storage batteries. This article explores some of these possibilities.

One of our young engineers has raised a question about the strength of the concrete required in a footing. She’s pointed out that, although our standard contract documents call for 3000 psi concrete in foundation elements, Table 4.2.1 of ACI 318-08 defines Exposure Class F1 as “Concrete exposed to freezing-and-thawing cycles and occasional exposure to moisture.”1 Table 4.3.1 effectively states that normalweight concrete in Exposure Class F1 must be produced with a minimum water-cementitious material ratio (w/cm) of 0.45 and a minimum strength of 4500 psi

When adequately mitigated, alkali-silica reactive aggregates can be used in concrete, but testing potential mitigation measures may require significant lead time. An alternative approach, CSA A23.2-27A, “Use of Supplementary Cementing Materials for Counteracting Alkali-Silica Reaction,” incorporates long-term performance data from laboratory prisms, outdoor exposure tests, and structures. It limits maximum alkali contents of concrete and minimum dosages of supplementary cementitious materials for use with known reactive aggregates. CSA A23.2-27A was introduced in 2000 and updated in 2004 and 2009. It’s the model for the new AASHTO PP65, and it will serve as a resource for the new ASTM Subcommittee C09.50 on Risk Management for Alkali-Aggregate Reactions