The Study of a Novel Propanesulfonate Lignin Ether with Good Water-reducing Performance in Concrete
Concrete admixture is one of the important components of concrete.As a kind of concrete admixture,the main function of water reducing agent is to reduce the water consumption of concrete without affecting its workability.Lignosulfonate superplasticizer,an environmentally friendly product,is prepared from pulp waste liquid as raw material with a simple production process.In this work,the novel type of propanesulfonate lignin ether(PSLC)superplasticizer was prepared by reaction of 1,3-propyl sulfonate(PS)and calcium lignosulfonate(LC)under NaOH catalyst.The effects of monomer feeding ratio,reaction temperature and reaction time on the fluidity of cement slurry were systematically studied.PSLC5 sample showed the fluidity of cement slurry of(250±1)mm with water cement ratio of 0.29 when synthesis condition was m(PS)∶m(LC)=1.27∶1 at 80 ℃ for 24 h,which was significantly better than that of raw LC(less than 80 mm).The structure and thermal properties of PSLC were characterized systematically through nuclear magnetic resonance spectroscopy(1H-NMR),Fourier transform infrared spectroscopy(FTIR),gel permeation chromatography(GPC),X-ray photoelectron spectroscopy(XPS),scanning electron microscopy(SEM)and thermo-gravimetric analysis(TGA).When the water cement ratio was 0.29,the fluidity of PSLC5 cement slurry was(250±l)mm better than that of N06((197±1)mm).After 60 min of static settling,the damage of PSLC5's flowability was only 3.2％,while N06 almost solidified without flowing.In order to achieve the same slump((215±5)mm)and spread((600±5)mm)of the concrete,the demand for PSLC5 was much less than for N06.The compressive strength of PSLC5 concrete was 22.3-43.8 MPa,which was higher than that of N06 at 3 days,7 days,28 days,respectively.And the water reducing rate of PSLC5 was 13％,higher than N06's 9.3％.In conclusion,PSLC5 exhibits better performance in concrete water reduction compared to N06.The excellent water reducing effect of PSLC is mainly due to the high electrostatic repulsion generated during absorption on the surface of cement particles.
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