Synthesis And Application Of Modified Calcium Lignosulfonate As High Efficiency Water Reducer

By means of chemical modification, studies on modification of calcium lignosulfonate, a green water-reducer, are carried out. Oxided by hydrogen peroxide and then purification, grafted with acrylamide through solution polymerization on the basis of the former modification products, polymerized of calcium lignosulofonate with large-monomers of maleic anhydride and PEG1000after esterification, and acrylamide, three modification products of calcium lignosulfonate, named MCL-1, MCL-2 and MCL-3respectively,are synthetized. Then one polycarboxylate superplasticizer is synthetized according to the technological conditions of MCL-3, and P1-CL is a combination product between P1 and the same content of calcium lignosulfonate in preraring MCL-3, both of which are used to compare with MCL-3 in properties.Through the tests of cement paste fluidity, adsorbance on cement particle surface, and IR, XRD, SEM of early-stage cement hydrates, influences of CL and MCL-1 on cement early-stage hydration and delayingmechanisms ofcoagulation are discussed.Results show that coagulation adjustability of gypsum is restrained and hydration of calcium silicates is lagely delayed by CL, and hydration of both aluminates and calcium silicates in cement is delayed in some certain at the present of MCL-1.Tests of cement paste fluidity, water-reducing rate, setting time, and each age compressive strength of hardened cement paste with different dosages of each water-reducer are made to study the application properties of CL, MCL-3, MCL-3, P1 and P1-CL. Integrated with surface tension tests of water solution of each plasticizer, content measurements of hydrate bounded water in cement paste after certain period of conserving age, XRD and SEM tests of hydrate, the influence mechanism on application performances of CL, MCL-3, P1 and P1-CL are discussed. The results show that both MCL-2 and MCL-3 improve the application performance of CL greatly, and the application performance of MCL-3 is superior to P1-CL.Application performance of each water-reducer is combined action consequences of their structures and their influences on hydration extent of cement paste and microstructures of hydrates of hardened cement paste.