Sodium Lignosulfonate Modification Research

Sodium lignosulfonates(LN) was produced as a by—product of pulp and paperindustry．It is a kind of renewable resources and has many advantages, such as richsource, cheap price, non-toxic, for the concrete water reducing agent use already hasmore than70years history. Sodium lignosulfonates has the function of retardingaction and air entrainment, it also has the small rate of Slump losses and bleedingrate.But because of its water—reducing ratio is low, the concrete compressivestrength of the increase was small, the concreting hours is too long so that in theconcrete application is limited. Therefore, the study that modified sodiumlignosulfonates becomes very important.This paper use the chemical method to modify the LN by using hydrogenperoxide as the oxidant, sodium sulfite as the sulfonating agent. Through orthogonalexperiment to determine the best technology of the modification and prepared theGLN. The sulphonated degree, foaming ability, surface tension, conductivity testing,the cement paste fulidity and influence on the concrete of GLN were tested, and theresults showed that, after modification, LN sulphonated degrees of improved, foamingability to drop, water—reducing ratio got increased obviously. When it is put with thedosage of0.75%, the cement paste fulidity is214mm, concrete water—reducing ratiois23.6%, and the compression strength ratio of concrete hardened for7d and28d，is140%and135%，which approach to the level of naphthalene water-reducing agent.Through to the modified sodium lignosulfonates and water reducing agent ofnaphthalene compound modification studies, and found that both excellentcompatibility, preparation of concrete pumping admixture GF-1with lower cost andperformance good points.The paper also research the modification that using sodium lignosulfonates tomodify amino-superplasticizer(ASP).Through the sodium lignosulfonates substitute20w%of phenol preparation of the modified amino-superplasticizer (ASM), throughthe test of cement paste fulidity of ASM, it is known that the ASM has the gooddispersancy for cement.When it is put with the dosage of is0.5%, the cement paste fluidity is260mm.Through the relevant test of concrete found that the ASM concretewater—reducing ratio is declined slightly than before modification, but bleeding rateto decrease, only1.6%, ASM had the better use effect with the high concrete waterretention. And the compression strength ratio of concrete hardened for7d and28d，isalso improved, it is up to160%and148%，which is higher than ASP.