| As a new type of bonding material applied to the back of tiles,tile back adhesive,which needs to be used in combination with cement mortar,is a newly emerging product designed and developed for the application of tile in China for recent years.Its application performance has attracted much attention.Due to the temperature difference stress damage caused by seasonal oscillation,ceramic tile often appears the phenomenon of hollowing and falling off,so it is necessary to study the mechanical properties of tile back adhesive in various weather-resistant environment.At the same time,based on the pozzolanic effect of fly ash,granulated blast furnace slag powder and silica fume in concrete and cement,it is proposed to mix them into the tile back adhesive to improve the adhesion between the tile back adhesive and cement mortar,so as to improve its mechanical properties.This paper studied the effects of fly ash,granulated blast furnace slag powder and silica fume on the mechanical properties of tile back adhesive in standard curing,thermal aging,water immersion and freeze-thaw environment.The mechanism was analyzed by Fourier transform infrared spectroscopy(FT-IR),X-ray diffraction(XRD)and scanning electron microscopy(SEM).The main conclusions were as follows:(1)Fly ash,granulated blast furnace slag powder and silica fume could significantly improve the bonding strength of tile back adhesive under various weather-resistant conditions.Compared with the bonding strength in standard conservation,the bonding strength increased in the thermal aging environment,and decreased under immersion and freeze-thaw conditions.With the extension of the time,the bonding strength in the standard conservation and thermal aging environment all showed an upward trend,while it showed a downward trend under the condition of immersion and freezing thawing.(2)FT-IR analysis showed that characteristic maps of tile back adhesive mixed with fly ash or silica fume was basically the same as the blank group.However,the vibration absorption peak of Si-O in the sample of tile back adhesive mixed with granulated blast furnace slag powder moved towards the higher wave numbers,and the degree of polymerization of the network increased.FT-IR analysis of cement paste hardener with tile back adhesive showed that the vibration absorption peak of C3 S in thesamples mixed with fly ash,granulated blast furnace slag powder and silica fume decreased,indicating that the addition of fly ash,granulated blast furnace slag powder and silica fume promoted the hydration of cement.(3)XRD results showed that compared with the blank group,the diffraction peak strength of C3 S,C2S and Ca(OH)2 were decreased in the samples mixed with fly ash,granulated blast furnace slag and silica fume,which further proved that the addition of fly ash,granulated blast furnace slag powder and silica fume accelerated the hydration of cement;with the extension of the time,the diffraction peak intensity of C3 S,C2S and Ca(OH)2 in each sample further decreased.It showed that the hydration degree of fly ash,granulated blast furnace slag powder and silica fume were more in-depth during this period,so as to improve the adhesive force of tile back adhesive and bonding mortar.(4)The results of SEM were in accordance with the macro-mechanical properties.It showed that the interface structure of the tile back adhesive with fly ash,granulated blast furnace slag powder and silica fume was denser in each weathering environment.With the extension of the time,the surface of the standard curing environment gradually formed more dense hydration product layer.The gel-like hydrated products accumulated in the thermal aging environment,and the density of structure was higher than that of standard curing environment.Under the condition of immersion and freezing thawing,the pore size of structure increased,the honeycomb gel structure between the particles was small,and the density of structure was lower than the standard curing environment. |
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