The Adsorption Of Polycarboxylate Superplasticizer By Montmorillonoid And Its Measurement Methods

This dissertation focused on the different characterization methods: gel permeation chromatography(GPC),ultraviolet and visible spectrophotometer(UV)and total organic carbon analyzer(TOC),for PCE adsorption.Afterwards,determining of the PCE adsorptions on clay minerals(montmorillonoid,illite,kaoline).And then,adding some sacrificial agents into the cement paste,in order to decreass the PCE adsorption on clays.The main experiments results were as follows:(1)The linearity range to PCE(0.50-10.00 g/L)and precision(RSD=0.7%)by GPC method were higher than the linearity range(0.50-4.00 g/L)and precision(RSD=0.8%)by UV method.After multiple measurement of montmorillonite adsorption balance,the reproducibility of the GPC method(The average relative standard deviation RSD=7.6%)was better than the UV method(The average relative standard deviation RSD=10.9%).During adsorption the metal ions dissolved from minerals lead to the deviations in the adsorption measurement results,which should be corrected by calculation.The deviations in adsorption quantity measuring by UV were obviously higher than that by GPC.The GPC method could eliminate disturbance of grinding aids effectively.(2)By GPC mehods,The saturated adsorption of montmorillonite,illite and kaolinite were about 13.6,3.28,1.73 mg/g.Montmorillonite had the largest adsorption which brought negative effect to the PCE working performance.With the temperature went higher,the PCE adsorption of these three clay minerals increased.The higher the pH of PCE was,the less the PCE was adsorbed.After these three clay minerals adsorbed on the PCE,electric potential would decrease(be more negatively).(3)The adding of clays decreased the cement paste fluidity obviously.When the content of clays achieved 4.0%,the cement paste almost lost fluidity after 60 min.Comparing the performance of nonionic(PEG,TPEG,polyving akohol)anionic(PEG-COOH),cationic(CTAB)organic substances working as sacrificial agents,experimental results indicated that:(1)Certain nonionic organic substances had sacrificial agents performance.PEG could improve the fluidity of the cement paste;the higher molecular weight PEG had higher sacrificial agents performance.Otherwise TPEG performance was similar to PEG-2000;the performance of polyving akohol was inferior to PEG.(2)Carboxyl-terminated PEG working as sacrificial agents were inferior to PEG.The decreasing extent of PCE adsorption order was PEG>PEG-COOH>HOOC-PEG-COOH.(3)The adding of CTAB instead increase the PCE adsorption on montmorillonite.