The synthesis of a new chitosan based superplasticizer and investigation of its effects on concrete properties

Abstract

Chitosan-g-POEGMA (Chitosan-g-poly[oligo(ethyleneglycol) methyl ether methacrylate]) graft copolymers are prepared by grafting of oligo (ethylene glycol methyl ether) methacrylate (OEGMA) on chitosan via redox free radical polymerization method using ceric ammonium nitrate (CAN) as the initiator at 40 °C. Then the resulting copolymers are sulphated by sulphuric acid, chlorosulfonic acid and fuming sulphuric acid (Oleum). The compounds are characterized by FT-IR, NMR, and Elemental analysis. The chitosan homopolymer is also sulphated to compare the results. Taking all characterization results and water solubility ratios into account, it is decided to conduct tests on concrete specimens containing graft copolymers sulphated with oleum sulfuric.Water-reducing properties in the fresh concrete have been examined. Compared to the reference concrete; it is observed that water-reducing of sulphonated graft is %6 and sulphonated chitosan is %5. The unit weights of the reference concrete is as 2380 kg/m3, sulphonated graft is as 2395 kg/m3 and sulphonated chitosan is as 2388 kg/m3. The air content of the reference concrete is measured as 2%, sulphonated graft as 1.5% and sulphonated chitosan as 1.6%. 28-day concrete durability results are determined as 30.1 MPa for the reference concrete, 34.7 MPa for sulphonated graft and 33.8 MPa for sulphonated chitosan.