Polymer Concrete
by Methaq. M / Iraq - Babylon University
Polymer
concrete is a material made up of different types of aggregates adhered by
polyester resins. PC is a composite material in which resin is used as
binder for aggregates such as sand or gravel instead of Portland cement. PC is
an inert product that can be cast in almost any shape . Due to its rapid
setting, high strength properties and ability to withstand a corrosive environment.
It is increasingly being used as an alternate to cement concrete in many
applications, construction and repair of structures, highway pavements, bridge decks, waste water
pipes and decorative construction panels. PC materials were originally developed
as a substitute for decorative stones.They
become particularly popular in construction industry during the early 1950’s.
Various resins such as
epoxies, Polyesters and acrylics have been used as binder in polymer concrete
production. However, recently vinyl ester, furan and polyurethane resins are
also incorporated for special-purpose polymer concrete. Unlike other resins,
application of polyester resins as binder to a weaker polymer concrete.
Nonetheless, they are the more commonly used resins in PC due to their lower
cost and reasonable performance.
To
produce PC, a monomer or a prepolymer (i.e., a product resulting from the
partial polymerization of a monomer), a hardener (cross-linking agent) and a
catalyst are mixed with the filler. Other ingredients added to the mix include
plasticizers and fire retardants. Sometimes, saline coupling agents are used to
increase the bond strength between the polymer matrix and the filler. To
achieve the full potential of polymer concrete products for certain
applications, various fiber reinforcements are used. These include glass fiber,
glass fiber-based mats, fabrics and metal fibers. Setting times and times for
development of maximum strength can be readily varied from a few minutes to
several hours by adjusting the temperature and the catalyst system. The amount
of polymer binder used is generally small and is usually determined by the size
of the filler. Figure above show the principle components of PC. Normally the
polymer content will range from 5 to 15 percent of the total weight, but if the
filler is fine, up to 30 percent may be required. A wide
variety of monomers and prepolymers are used to produce PC. The polymers most
frequently used are based on four types of monomers or prepolymer systems: methyl
methacrylate (MMA), polyester prepolymer-styrene, epoxide prepolymer hardener (cross-linking
monomer) and furfuryl alcohol.
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