Properties Of Intercalating-modified Welan Gum And Its Effects On The Performance Of Mortar

As one kind of new thickener admixtures,welan gum has a great potential application prospect due to its well rheological properties,thermal endurance and salt tolerance.However,compatibility between welan gum and superplasitcizers,especially for polycarboxylate-based type?PCE?has limited the development of welan gum applied into building materials.A new kind of modified welan gum,called Intercalating-Modified Welan Gum?IMWG?,was made with layered inorganic material and welan gum through intercalation method.To figure out the actual applicationeffectofIMWG,especiallyforCementitiousSelf-Leveling Mortar?CSLM?which was prepared rarely with welan gum in some domestic or foreign references,the character nature of IMWG and its effect on working mechanism and hydration process of mortar material was conducted in this study compared to welan gum?WG?or hydroxypropyl methyl cellulose ether?HPMC?.Such research results were draw below:1)To some extent,welan gum could intercalated into layered double inorganic materials?LDIs?.Both WG and IMWG solution was proved to typical pseudoplastic liquid.However,under the same mass concentration,the solubility and apparent viscosity values of IMWG was lower than that of WG owing to the layer attraction force induced by LDIs.2)There was well compatibility between IMWG and PCE,which referred less competitive adsorption between welan gum and PCE.Besides,high fluidity and well early mechanical strength development of CSLM was achieved with IMWG adding acting as thickener.Compared with WG or HPMC,initial fluidity values,fludity loss and rheological properties of CSLM prepared with IMWG was improved obviously.The recommend dosage of the IMWG?according to the effective dosage?in CSLM is0.01%to 0.05%.3)Delay releasing effect of welan gum was achieved through the layer attraction force of LDIs on welan gum in IWMG,thus improving the compatibility between welan gum and other admixtures.Besides,net-like structure in both IMWG and WG solution were observed,which means the physical properties of welan gum was not changed when WG turns into IMWG.Using XRD method and ESEM analysis,the effect of IMWG on hydration products of CSLM was observed.Ettringite,the main early hydration products in CSLM made with sulphoaluminate cement,nucleated and grew well with IMWG adding and less retarding effect of welan gum on ettringite nucleation was found in IMWG system due to the layer attraction force.C-S-H gel,especially fibrous-types C-S-H gel,the main early hydration products of the CSLM made with superfine ordinary Portland cement was observed with IMWG adding compared to that with WG because the solubility of hydration mineral,like C₃S,was disturbed little by IMWG.Besides,another hydration product,Ca?OH?₂ appeal to less preferred orientation with IMWG introducing.