Dedolomitization and alkali reactions in Ohio-sourced dolstone aggregates

"November 2017."; "FHWA/OH-2017-9"--Technical report documentation page.; Includes bibliographical references (pages 24-26 of Final report).; Final report;; Sponsoring agency: Ohio Department of Transportation; State job number 135267Final report (4 unnumbered pages, 83 pages) -- Fact sheet: Breakdown of dolostone aggregates in alkaline cement concrete environment (2 unnumbered pages).Concrete samples produced using NW-Ohio sourced aggregates were evaluated for susceptibility to degradation and premature failure due to cracks formed by the volume expansion during hydration of silica gels produced by alkali-silica reactions between alkaline Portland cement and dolostone aggregates. Expansion tests were performed on concrete prisms produced using NW-Ohio sourced dolostone aggregates. After the expansion tests, concrete samples were characterized using Polarized Light Microscopy (PLM), Scanning Electron Microscopy (SEM) with Energy Dispersive Xray microanalysis (SEM/EDS), and X-ray Powder Diffraction (XRD). The results demonstrate significant amounts of dedolomitization, but little if any alkali-silica reaction (ASR) occurred at least over the one-year duration of the expansion tests. The lack of excessive expansion and cracking due to ASR in these concrete samples reflects the very low amounts of reactive silica phases found in the aggregates used in this study