Special-Uses-Alkali - Expanded Shale & Clay

Materials other than either Class N or F fly ash also successfully mitigated ASR, and can haveapplications in Colorado. Lithium can mitigate ASR without any cement replacement, althoughblends with fly ash tend to be more economical.Lightweight sands can mitigate ASR by replacing reactive sands and giving a pore structure forgel from the coarse aggregate to grow in safely.ASR mitigation with lightweight sand also brings the benefits of “internal curing” to dense, lowwater to cement (w/c) ratio concrete that can be difficult to cure in the field.Implementation StatementCDOT should modify the concrete specifications to allow the use of alternate materials, pendingcompliance to the new specifications and successful testing before being placed on the CDOTApproved Products List APL). A review of specifications in other states and this report should behelpful.Implementation into concrete construction (after specifications allow alternate materials) willinvolve economic evaluations by the contractors. Potential Class F shortages will likely promotemix designs with alternate materials as a backup, or if strength gain (with less cementreplacement) is beneficial to the project schedule.v