Effect of XG/KGM hydrophilic colloid on gelling characteristics of fly ash slurry
The poor water retention and susceptibility to drying and cracking of fly ash limit its application.To improve the water retention performance of fly ash,a fly ash slurry containing hydrophilic colloids was prepared by adding different mass ratios of xanthan gum(XG)and konjac gum(KGM)hydrophilic colloids to the fly ash slurry.The material's cementitious properties,stability,and rheological properties were tested,and its gelation mechanism was analyzed.The results showed that the gelation state of XG/KGM hydrophilic colloidal fly ash slurry varied with different mass ratios.When the mass ratio was greater than 4∶6,the fly ash slurry can gelation,and the lowest thermal water loss rate was 18.14%at 120℃.The stability was good,and the absolute Zeta potential values were all above 20 mV.The maximum mass loss at 1000℃was about 6.27%;The rheological experiment showed that there was shear thinning phenomenon in all coal ash slurry,which was a pseudoplastic fluid.The Herschel-Bulkley model was used for fitting,and the R2 was above 0.99;The energy storage modulus G′ was higher than the loss modulus G″,indicating that the fly ash slurry mainly had elastic properties;When the mass ratios of the three groups that can form gels were 6∶4,8∶2,and 10∶0,irregular block and sheet shaped hydrophilic colloids can be observed on the surface of the samples;The gelation mechanism indicated that complex interactions can occur between fly ash and XG,XG and KGM,thereby promoting the gelation of fly ash slurry.
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