Influence Of Polycarboxylate Superplasticizer Synthesized By AMPS On The Dispersion Property Of Cement-montmorillonite Slurry

Due to the designability and multifunction,polycarboxylate superplasticizer has became the current development direction of the water-reducing agent.The most commonly used polycarboxylate superplasticizer at this stage is AA-TPEG(PCE)with the PEG long side chain synthesized by acrylic acid and allyl polyoxyethylene ether.However,traditional PCE exhibits poor compatibility when concreted with clay.It is difficult to control the fluidity loss caused by the clay minerals.As a result,PC is difficult to be used stably.Therefore,the study of reducing the sensitivity of PC to clay is particularly important.The current researches mainly focus on synthesis of MAA-HAMA as the low clay sensitive superplasticizer.The adsorption of polycarboxylate superplasticizer on montmorillonite is reduced.Thus,more polymer can be adsorbed on the surface of the cement particles to achieve a better dispersion property.However,the water reducing efficiency and dispersion retention of this type of water reducing agent is poor.As a result,this type of water reducing agents is not widely used in engineering application.Therefore,it is of great engineering significance to reduce the clay sensitivity of AA-TPEG water-reducing agent and to improve the water-reducing efficiency of MAA-HAMA type water-reducing agent.The polycarboxylate used in ceramic slurry synthesized with 2-acrylamide-2 methyl acrylic sulfonic acid(AMPS)was reported to exhibit high dispersion ability.When AMPS was used to synthesize polycarboxylate as cement water reducing agent,the absolute value of the Zeta potential on the cement particles surface increased leading to the improved dispersion property.In this paper,new types of water reducing agent ATS,MPS and MES were synthesized by introducing AMPS monomer on the basis of PCE and MAA-HAMA.The effects of these water reducing agents on the clay sensitivity were studied.The effect of the adsorption thickness,adsorption capacity,adsorption mode and Zeta potential of cement and montmorillonite were studied.The reason why the water-reducing agent containing AMPS components reduces clay sensitivity was analyzed.Research indicates:1、Compared with PCE,the adsorbed amount of ATS copolymers with AMPS on the montmorillonite is slightly increased.However,the total adsorption amount of ATS copolymers on cement and montmorillonite decreased by about 17%.The absolute value of zeta potential and the adsorbed layer thickness on the cement particles with ATS copolymers are increased,so the dispersibility of the cement and clay particles are increased.With the help of ATS copolymers with AMPS monomer,the cement-montmorillonite slurry and mortar exhibited the better dispersion and flowability retention.In the system of mortar with machine sand containing montmorillonite clay,the usage of ATS was reduced by 9.2% for the same initial fluidity,and the fluidity loss over one hour was reduced by 26.3%.Thus,the ATS copolymers exhibited a lower clay sensitivity.2、The MPS and MES was adsorbing on the surface of montmorillonite.The adsorption capacity was much lower than that of PCE.With the increase usage of AMPS monomer,the adsorption capacity of MPS and MES on cement and montmorillonite increased slightly,the absolute value of zeta potential and the adsorbed layer thickness on the surface of particles was also increased.Compared with MP and ME,the dispersion ability of MPS and MES in cement and montmorillonite was enhanced.With the help of MPS and MES copolymers with AMPS monomer,the cement-montmorillonite slurry exhibited the better dispersion.And the clay sensitivity became lower with the increase usage of AMPS monomer.Due to the shorter side chain of MP,ME,MPS and MES,the dispersion of cement without montmorillonite was less than that of PCE.But its clay sensitivity was lower than of PCE.