Study on a Hydrogel for Adsorption of Chloride Ions in Cementitious Materials

Abstract

Chloride ions in the seaside environment can corrode the steel reinforcement in concrete, which greatly endangers the safety of seaside structures. As an excellent adsorption material, hydrogel is widely used in the field of water treatment but is rarely used in cementitious materials. In this study, a polyacrylamide–chitosan hydrogel (PAMC) was prepared with N,N-methylenebisacrylamide as the cross-linking agent and acrylamide as the monomer. The prepared PAMC gel could effectively adsorb chloride ions in simulated seawater and simulated sea sand environments, and the maximum adsorption capacity of chloride ions by PAMC-1 (prepared from 2.5 g acrylamide and 1% content of N,N-methylenebisacrylamide relative to acrylamide) gels in simulated seawater was 55.53 mg/g. The adsorption behavior of the PAMC gels in solution fit the Langmuir isotherm model. The composition and morphology of the PAMC gel were characterized, and the responsiveness of the PAMC gel to the environment was studied. The results showed that the PAMC gels adsorbed better in alkaline environments and thus could be used in alkaline cement-based environments. The mortar sample containing the PAMC-1 gel had higher resistance to chloride ion penetration, and the chloride ion content at 7.5–10mm from the surface of the sample cured for 28 days was reduced by 41.4% compared to the samples without the gel.

Using polyacrylamide hydrogel to adsorb chloride ions in cement-based materials

“…However, studies on the adsorption of chloride ions in concrete by gels are rare and some methods are not suitable for use in buildings because of the high cost of materials. For example, Chen's 20 group studied a kind of double network gel based on chitosan and this gel could adsorb chloride ions in cement. However, chitosan is not suitable for use in real buildings be-cause (1) chitosan is a kind of natural polymer.…”

Modification of Macromolecules of Polyimide Films by Electron Irradiation

“…The intensive introduction of new polymeric and composite materials in technology and industry poses the problem of finding ways to develop them, so detailed studies are needed on their composition and structure, as well as the physicochemical processes occurring in each case. The physicochemical properties of polymeric materials are due to their specific structure in the form of a large number of repeating structural units interconnected by covalent chemical bonds [1][2][3][4]. Polyimides are widely used in the production of semiconductor devices.…”