within one hour (2- ↔ 2-inch specimen) at temperatures of 20C (2F), when the surfaces
are protected from quick heat loss by covering with regular polymeric materials. Areas that
need further exploration are exothermic heat control, improving hydraulicity, and freeze
thaw durability.
Magnesia cements
There are magnesium-oxide-based cements known as magnesium oxychloride and
oxysulfate cements. These cements have very poor stability in moist environments and
therefore have not enjoyed much widespread use for outdoor applications.
Sulfur cement
Commercial development of sulfur concrete started in the 1970s in order to find poten-
tial markets for elemental sulfur. The sulfur concrete consists of elemental sulfur, sulfur
polymer stabilizer, fine filler material, and aggregates. Mix proportioning is accomplished
using a suitable dense-graded aggregate in combination with sulfur and filler to provide
good workability for the application. Sulfur concrete is produced by a hot mix procedure
similar in some respects to that of asphalt.
Sulfur concrete is a construction material with unique properties and characteristics. It
performs very well in many aggressive environments and offers many benefits as an alter-
native construction material, particularly in situations that require a fast setting time, place-
ment in excessive cold or hot climates, corrosion resistance, and impermeability.
ORGANIC POLYMER RESINS
Many polymeric systems can be used to prepare polymer mortar and concrete by com-
pletely replacing the cement hydrate binders of conventional mortar and concrete with
polymeric binders. A wide range of aggregates and monomers can be used, although the
cost and properties of the polymer concrete are strongly influenced by the gradation and
monomer. A well-graded aggregate may require as little as 5 to 8% monomer by weight,
while more than 15% may be required for gap-graded aggregate. Most of the thermosetting
resin and monomer systems for the polymer mortar and concrete are polymerized at ambi-
ent temperatures, which can vary from normal weather to cold weather.
In polymeric cement systems, the cement hydrate binders of conventional mortar and
concrete are replaced with polymeric binders, and the aggregates that are the same as the
conventional products are strongly bound to each other by the uniform polymer matrix
phases obtained from the polymeric binders. Accordingly, compared to ordinary cementitious
materials, properties such as strength, adhesion, water-tightness, chemical resistance, freeze
thaw durability, and abrasion resistance of polymeric cement systems are generally im-
proved to a great extent by polymer replacement. On the other hand, the poor thermal and
fire resistance and large temperature dependence of mechanical properties are some draw-
backs caused by the undesirable properties of the polymer matrix phases.
The processing technology of polymeric cement systems is the same as that of the con-
ventional cement systems, so that the batching, mixing, and placing techniques for regular
cement products are applicable for polymeric systems. However, the curing methods are
different. The optimum cures, such as dry cure at ambient temperature or heat cure, are
applied to polymeric cement systems. Generally, the process technology of the polymer
systems is divided into two categories: cast-in-place and precast application systems. At
present, the cast-in-place application systems are chiefly applied for the polymer mortar,
and the precast application systems are used for the polymer concrete. In order to reduce
the cost of polymer mortar and concrete systems, it is very important to find out the effec-
tive mix proportions of the polymeric binders and the aggregates. Any of the polymeric
binders are toxic and flammable and therefore the established safety procedures should be
strictly followed.
13
Previous Page
