Review and discussion of polymer action on alkali–silica reaction

Abstract

This paper compares the factors known to influence the deleterious alkali-silica reaction in concrete with the properties that polymers tend to modify in cementitious materials. A discussion on the potential ASR-influencing mechanisms of polymer additions is provided, along with a critical review of the existing literature on the subject. The influence of the potentially significant differences in mechanical properties and sorptivity between polymer-modified and unmodified cementitious materials on the expansion results of alkali reactivity tests is also discussed. According to the available results, the influence of polymers on ASR-related expansion seems to depend on both polymer type and dosage, suggesting the existence of concurrent, not yet well understood mechanisms by which polymers may influence ASRrelated expansion. As polymer modification of cementitious materials can lead to significantly lower modulus of elasticity, higher tensile strength and resistance to microcracking, it is suggested that further research on the subject includes not only expansion tests but also an assessment of the resistance of polymer-modified cementitious materials to ASRrelated damage, the main concern due to this deleterious phenomena.

Dimensional Stability of SBR-Modified Cementitious Mixtures for Use in 3D Additive Construction

“…The cause of decrease in drying shrinkage due to the increase in SBR/cement ratio was explained by Mei et al [26] and Feiteira et al [27] as the result of polymer film formation in latex-modified cement mortar. The film acts as a microfilament, controlling the contraction phenomenon in the matrix and preventing moisture evaporation by blocking pores.…”

Towards more sustainable building based on modified Portland cements through partial substitution by engineered feldspars

“…The European regulations in force (UNE-EN 197-1:2011) clearly state the allowed cement additions in Europe, such as blast furnace slag [10,11], fly ash [12], silica fume [10,13], limestone [13] and pozzolans [14,15]. The term pozzolanic is generally used to define materials which are cementitious by themselves, having a chemical composition that, at room temperature and combined with lime in the presence of water, forms stable and insoluble compounds which behave as hydraulic conglomerates [17]. The Ca(OH) 2 required for the pozzolanic reaction can come directly from the hydrated lime or from the hydration of the Portland cement.…”

“…Alkaline contents could favor the alkali-silica reactions (ASR) degrading the cement pieces due to the expansions phenomena. This effect is a very important problem that involves great amount of research works, where the alkalis release in pore solution and the mortars expansion is study by the influence of several parameters, such as humidity, pH, temperature, etc [16,17]. Conversely, feldspars chemical composition includes Ca, Si and Al cations and, therefore, pozzolanic properties could be expected and, in addition, it can provide other functionalities, as whiteness, hardness, etc.…”

Improvement of thermal efficiency in cement mortars by using synthetic feldspars

“…However, the use of feldspar in cementitious applications is limited due their alkali content, which could favor the alkali-silica reactions (ASR) degrading the mortar due to the expansion phenomena. This effect is a very important problem that involves great amount of research works, where the alkalis release in pore solution and the mortar expansion is studied by the influence of several parameters, such as humidity, pH, temperature, etc [22][23][24]. At present, new synthetic feldspar is developed in order to be able to design and develop new functional properties.…”