Analysis of Compressive Strength Development and Carbonation Depth of High-Volume Fly Ash Cement Pastes

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Title: Analysis of Compressive Strength Development and Carbonation Depth of High-Volume Fly Ash Cement Pastes

Author(s): Xiao-Yong Wang and Ki-Bong Park

Publication: Materials Journal

Volume: 113

Issue: 2

Appears on pages(s): 151-161

Keywords: carbonation; compressive strength; dilution effect; high-volume fly ash; hydration; model; pozzolanic reaction

Date: 3/1/2016

Abstract:
ACI Materials Journal/March-April 2016 151 ACI MATERIALS JOURNAL TECHNICAL PAPER High-volume fly ash (HVFA) concrete, which typically has 50 to 60% fly ash as the total cementitious material content, is widely used to achieve sustainable development in the concrete industry. Strength development and carbonation are critical research topics for using HVFA concrete. This paper presents a numerical procedure to evaluate the strength development and carbonation depth of HVFA concrete. This numerical procedure consists of a hydration model and a carbonation reaction model. The hydration model analyzes the fly ash dilution effect and the pozzolanic reaction. The amount of carbonatable materials, such as calcium hydroxide (CH) and calcium silicate hydrate (CSH), are calculated using reaction degrees of cement and fly ash. The compressive strength development of cement-fly ash blends are evaluated from CSH contents. The calculation results from the hydration model, such as the amount of carbonatable materials and the porosity, are used as input parameters for the carbonation reaction model. By considering the effects of material properties and environmental conditions, the carbonation reaction model analyzes the diffusivity of carbon dioxide and the carbonation depth of HVFA concrete with different curing conditions, different fly ash contents, and different water-binder (w/b) ratios.