7 - Fabrication and Properties of Liquid Resin and Monomer-Modified Systems

Abstract

This chapter focuses on the fabrication technique and properties of liquid resin and monomer-modified systems. Most liquid epoxy resins for cement-modifiers are synthesized by the reaction of one molecule of bisphenol with two molecules of epichlorohydrin and contain two functional groups— that is, epoxide and hydroxyl groups. In general, epoxy resin systems as cement modifiers are supplied as two-part systems, which consist of epoxy resin parts and hardener or curing agent parts, and contain surfactants to effectively disperse the epoxy resins throughout the mortars or concretes and antifoaming agents to prevent excessive air entrainment. Epoxy-modified systems are hardened by the simultaneous progress of cement hydration and epoxy polymerization. The hardened or cured epoxy resins form irregular thin epoxy layers on the cement hydrates, and the epoxy layers bind the cement hydrates together to form a network structure in which the epoxy phase interweaves throughout the cement hydrate phase. This network structure acts as a matrix phase for the epoxy-modified systems, and the aggregates are bound by the matrix. The fabrication procedure of monomer-modified systems is similar to that of liquid resin-modified systems, except monomers are used instead of liquid resins. These systems are prepared by directly mixing the monomers with cement, aggregate, and water, followed by thermal-catalytic or radiation polymerization process. The polymerization occurs during and/or after the setting or hardening of the cement systems. Finally, the polymerization process converts the monomer-modified systems to polymer-modified systems.