The Modification Of Calcium Lignosulfonate As Water Reducer

Calcium Lignosulfonate (CL) was produced as a by-product of pulp and paper industry, separated from lignum by a sulfite pulping process. It was most widely as common water reducer for extremely versatile in performances and cheap price.However, CL was of relative low water-reducing ratio with retarding action and air entrainment, especially at high dosage, which restricted its application. Therefore, the modification of CL had attracted great attentions.Two types of modified Calcium Lignosulfonates (ACL,CCL) were synthesized respectively used p–Aminobenzene sulphonic acid and p-Aminobenzene acid as main raw materials at optimum reaction conditions established by the orthogonal experiments. The surface tension, foaming ability, and absorbing amount of ACL and CCL on cement particles were tested, and the zeta potential of cement particles with ACL and CCL was determinated, also the effect of the three water reducers on the cement hydration and products was discussed, in addition, the viscosity of cement paste with ACL and CCL was measured, which were to investugate the surface activity of ACL and CCL and the electrical properties of the cement paste, and to further evaluate the effects of modified Calcium Lignosulfonates on cement hydration, hydration products and rheological property of cement paste. The performances of mortars modified by ACL and CCL such as the W/C ratio, air content, compressive and flexural strength were assessed. Based on the above investigation results, the following conclusions could be drawn:(1) ACL was of lowest surface activity among three water reducers, and the surface activity of CCL was lower than that of CL.(2) The absorbing amount on the cement particles surface of ACL was lower than that of CL and higher than that of CCL. (3) Under the same dosage, the zeta potential of cement particles with ACL was more negative than that with CCL, and that with CCL was a little more negative than that with CL. With the hydration time elapsed, the change of zeta potential of cement particles with ACL and CCL was less than that with CL, and that with ACL was least.(4) ACL and CCL were of retarding effect. The retarding effect ACL and CCL were decreased compared with CL.(5) At the same dosage, ACL was of best disperse ability to cement particles, and the viscosity of cement paste of CCL is less than that with CL at the same water-cement ratio, during the hydration progress.(6) At the same fluidity of mortar and dosage of water reducers, the W/C ratio and air content of mortars with ACL was lower than those with CL and CCL, and those with CCL was lower than those with CL. The compressive strength and the flexural strength of mortars with ACL were higher than those with CCL, while those with CCL were higher than those with CL.