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A new methodological approach for evaluating the effectiveness of various types of inhibitors of alkali-silica reaction (ASR) in concrete is proposed and validated through its application to literature data. This approach is based on innovative parameters of reactivity, such as the Threshold Level of Alkali of an aggregate, the driving force of the expansion process ASR tolerable by the concrete and the potential contribution that a minimum of alkali inhibitor is able to provide the mixture of concrete. The article also described the experimental procedure for the determination of these parameters.
A methodological approach, based on some innovative reactivity parameters such as the threshold alkali level (TAL) of aggregates and the tolerable driving force (Δtol) of the deleterious expansive process associated with alkali–silica reaction (ASR), is proposed in order to assess the alkali-reactivity of aggregates and compare the effectiveness of different types of ASR inhibitors (low-alkali Portland cements, lithium compounds, and blended cements manufactured with active mineral additions). The effectiveness of the ASR inhibitors, expressed in terms of Δtol, is related to the naturally available alkali content of concrete and the TAL of the aggregate used in the concrete mix. The potential minimum contribution of alkalis (Lim) by a given ASR inhibitor to the concrete mix is proposed as a specific efficacy parameter. The relationships between the effective dose levels of mineral additions or lithium compounds and the efficacy parameters Δtol and Lim have also been identified. The test procedures for the experimental determination of such parameters are described and some methodology applications to published ASR expansion data are reported.
31 Dicembre 2012
Sviluppo del Sistema e della Rete Elettrica nazionale (RETE 2012)