Abstract:

The graft sulfonation of acid precipitation lignin was carried out by introducing active groups to improve the sulphanating activity. The structure of the obtained graft sulfonation lignin was then investigated by IR , and the water reducing-performance strengthening ability was also discussed. The results show that (1) many sulfonic groups and phenylic hydroxyl groups are introduced into the graft sulfonation lignin , and the methoxyl groups are
substituted by active groups , thus improving the activity of the produced lignin , (2) as to the two superplasticizers (MCL1 and MC12) prepared by mixing the graft sulfonation lignin with calcium lignosulfonate in the lignin con-tents of 70% and 60%，the fluidity of the cement paste with 0.6% combined products is more than 230mm when the water to cement ratio reaches 0.28 , and the initial setting time and final setting time of the cement paste with o. 8 % combined products are respectively 50~ 80 min and 6~ 7 h retarded; and (3) the water-reducing ratio of the mortar with 0.8% MCL1 is 25.5% , and the 7-day and 28-day compressive strength ratios are respectively 135% and 123%， which means that the water reducing-performance strengthening ability of the combined product is simi-lar to that of naphthalene series superplasticizer FDN.

Key words: acid precipitation lignin, superplasticizer, modification, graft sulfonation