Interfacial transition zone of cement paste-reactive aggregate in cement-zeolite mortars

Abstract

Abstract. Alkali-aggregate reaction is an expansive chemical reaction between the alkalis present in cement paste and minerals contained in aggregates. Mineral admixtures can mitigate the detrimental processes caused by this reaction. One of the minerals that reduce the effects of the alkali-aggregate reaction is natural zeolite. This study attempts to explain the process that takes place in the zone surrounding reactive gravel in the cement mortar made with an addition of natural zeolite. Mortar bar expansion tests were performed and a scanning electron microscope equipped with an energy-dispersive X-ray spectrometer was used to observe the paste-aggregate interfacial zone. The results confirmed the influence of the zeolite on the reduction in reactive aggregate-based mortar expansion. The microstructure of the aggregatepaste interfacial region was described and particular sub-zones varying in terms of calcium, sodium, potassium and silicon contents were determined.

Microstructure and Degradation of Mortar Containing Waste Glass Aggregate as Evaluated by Various Microscopic Techniques

“…This is because waste glass, unlike glass fibres deliberately manufactured for use in concrete, is not coated to counteract ASR [31]. Degradation of the cement composite with waste glass is not the rule, although the results of standard expansion tests often indicate an increased different products are identified [12,46]. They may take various forms of loose gels with a "house of cards" [27,47] structure or sword-like or rosette-like morphologies [48].…”

“…Such products can often be observed in the air voids in concrete with reactive aggregate. Due to usually limited space in which the ASR products can be formed, their formation in the form of a dense alkali gel is often observed [7,8,46]. These products cause stresses leading to cracks in the aggregate, which are then transferred to the surrounding paste [10,46,49].…”

Scientific basis and rules of thumb in civil engineering: conflict or harmony?

“…In 2015, a special issue of the Bulletin of the Polish Academy of Sciences: Technical Sciences dedicated to diagnosis and durability of buildings was published [13]. Studies published in that issue: K. Flaga [14]; Z. Owsiak et al [15,16]; Z. Rusin et al [17]; L. Czarnecki, P. Woyciechowski [18]; B. Goszczyńska et al [19]; K. Wilde et al [20]; A. Garbacz [21]; Z. Hoła [22]; M. Iwański [23]; A. Szydło [24]; A. Piekarczuk et al [25]; M. Kolbrecki [26]; D. Kowalski et al [27] are considerable evidence of achievements and research ambitions in this area.…”

Degradation of Glaukonite Sandstone as a Result of Alkali-Silica Reactions in Cement Mortar

“…The texture can reveal, for example, some specific distribution of reactive and unreactive phases in aggregate. The case in which the whole aggregate particle contains only one reactive mineral phase is very rare in nature [ 17 , 18 ]. However, those cases are usually considered in model tests [ 19 , 20 , 21 , 22 , 23 , 24 ].…”