Timing aeration curing to balance neutralization and strength in stabilized construction-generated soil

Le résumé fourni par la source

ABSTRACT Construction-generated soil stabilized with cement- or lime-based binders becomes strongly alkaline through the liberation of Ca(OH) 2 , a condition that impedes vegetation, threatens water quality and thereby limits reuse. Aeration curing, carbonation of Ca(OH) 2 to CaCO 3 by ambient atmospheric CO 2 , is the least-cost neutralization route, but no guidance exists on when aeration should begin after binder mixing. This study treats the sealed-curing duration imposed between binder mixing and the start of aeration as an independent design variable and quantifies its coupled influence on pH-neutralization behavior and 28-day unconfined compressive strength (UCS) for two contrasting binder chemistries: a quicklime-rich lime-based binder and ordinary Portland cement (OPC). For the lime system, in which Ca(OH) 2 is generated almost instantaneously by slaking, the sealed period had no effect on the neutralization trajectory (terminal pH ≈ 11.4). For OPC, in which Ca(OH) 2 is released progressively by hydration, longer sealing accelerated only the early pH reduction; re-plotted against total elapsed time since mixing, all cases collapsed onto a common trajectory (terminal pH ≈ 9.9), demonstrating that sealing merely time-shifts neutralization rather than adding capacity. In contrast, UCS increased modestly but monotonically with sealed period for both binders (15-18 % at a 7-day seal). The terminal-pH plateaus, fixed by CaCO 3 -bicarbonate buffering, impose a binder-dependent lower bound that neither extended sealing nor extended aeration can overcome. The practical implication is that immediate aeration is optimal where neutralization alone governs, whereas sealing is warranted only where strength is required; a compact process-selection framework linking sealed duration, aeration duration, binder chemistry and performance targets is proposed.

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