Polymer Portland cement concrete

PPCC mixtures are Portland cement concrete mixtures to which polymer latexes have been added during the mixing process. Hardening of the polymer occurs simultaneously with the curing of concrete thus forming a continuous polymer network throughout the concrete [11, 16]. 

Although many different polymers were investigated for use in PPCC, latexes are the most widely used binders. The latexes that are in general use are styrene-butadiene rubber (SBR) and chloroprene rubber (CR) which are elastomeric polyacrylic ester (PAE), ethlene-vinyl acetate (EVA) and poly(styrene-acrylic ester) (SAE) which are thermoplastic. Besides latexes, epoxy resins, which are thermosetting, are also used in PPCC [11, 17]. 

After one day of moist curing and at least three days of air curing at 7-30 °C, the PPCC can be put safely into service [11]. Rewetting may result in re-emulsifying or redispersion of the latex with consequent strength reduction. 

The most important feature of PPCC is its excellent bonding characteristics. However, this may sometimes cause problems of form removal unless suitable release agents are placed on forms [11]. 

PPCC applications include deck coverings, floors, pavements, precast units, anti-corrosive linings, adhesives, patching or repairing Portland cement concretes [11, 17]. 

---

Concretes with polymers are generally classified into three categories as polymer concrete (PC), polymer Portland cement concrete (PPCC), which is also known as latex-modified concrete (LMC) and polymer-impregnated concrete (PIC) according to their process technologies. 

Traditional ceramics also include the concretes, which are composites consisting of rock, gravel, and sand, bonded together with some type of cement. Typical materials used are Portland cement or one of several polymers. Portland cement concrete and polymer concretes have been discussed in the previous chapter. 

A.Al-Negheimish (1988). Bond Strength, Long Term Performance and Temperature Induced Stresses in Polymer Concrete-Portland Cement Concrete Composite Members. Ph.D. Dissertation, The University of Texas. 

Pull-out tests were also conducted to measure the bond strength between the polymer concrete overlay and the Portland cement concrete substrate before and after the thermal compatibility test. The results are shown in Table 9. 

According to the ASTM C-884-78, delamination of the polymer mortar layer from the concrete test block or the presence of horizontal cracks in the concrete near the interface shall constitute failure. It is obvious from these results that the RPUMRPE mortar passes the ASTM C-884-78. After thermal cycling, no delamination was found in the specimens. The failure in all specimens in the shear and pull out tests occurred within the portland cement concrete substrate. These results depended on the tensile strength of the concrete substrate. 

As shown in Table 2.7, the coefficient of chemical resistance of RubCon is 1.0 for water, 0.81-0.95 for all mineral acids (exception is KCI = 0.69 for 36% solution of hydrochloric acid), 0.82-0.95 for organic acids, 0.82-0.91 for alkalis, 0.88 for solvents and petroleum products, and 0.84-0.86 for solution of salts. The analysis of experimental data has shown that RubCon offers universal chemical resistance many times higher than ordinary Portland cement concrete and surpasses the chemical resistance of polyester, polyepoxy, and vinyl ester polymer concrete. It is worth noting that penetration depths of 5% nitric and 36% solution of hydrochloric acids into RubCon sample bodies were 3, 4, and 5.1 mm, respectively the penetration ability of these acids is higher as compared with other corrosive environments. 

RubCon offers universal chemical resistance many times higher than ordinary Portland cement concrete and surpasses the chemical resistance of polyester, polyepoxy, and vinyl ester polymer concretes. 

PIC is a precast and cured portland cement concrete that has been impregnated with a monomer that is subsequently polymerized in situ. This type of cement composite is the most developed of polymer-concrete products. PCC, on the other hand, is a modified concrete in which a part (10%-15% by weight) of the cement binder is replaced by a synthetic organic polymer. It is produced by incorporating a monomer, prepolymer-monomer mixture, or a dispersed polymer (latex) into a cement-concrete mix. To effect the polymerization of the monomer or prepolymer-monomer, a catalyst (initiator) is added to the mixture. The process technology used is very similar to that of conventional concrete. So, unlike PIC which has to be used as a precast structure, PCC can be cast-in-place in field applications. PC can be described as a composite that contains polymer as a binder instead of the conventional portland cement. 

Other tertiary recycling processes that have been developed include a Freeman Chemical Corp. process to convert PET bottles and film to aromatic polyols used for manufacture of urethane and isocyanurates. Glycolized PET, preferably from film, since it is often lower in cost than bottles, can be reacted with unsaturated dibasic acids or anhydrides to form unsaturated polyesters. These can then be used in applications such as glass-fiber-reinforced bath tubs, shower stalls, and boat huUs. United States companies that have been involved include Ashland Chemical, Alpha Corp., Ruco Polymer Corp., and Plexmar. Unsaturated polyesters have also been used in polymer concrete, where the very fast cure times facilitate repair of concrete structures. Basing polymer concrete materials, for repair or precast applications, on recycled PET reportedly leads to 5 to 10 percent cost savings and comparable properties to polymer concrete based on virgin materials. However, they are still approximately 10 times the cost of portland cement concrete. There appears to be little commercial application of these processes at present. 

Concrete Bridge Protection and Rehabilitation Chemical and Physical Techniques—Corrosion Inhibitors and Polymers. Discusses the improvement of existing non-electrochemical methods for protecting and rehabilitating chloride-contaminated concrete w ith and without concrete removal and the development of new methods. Five corrosion inhibitors were evaluated and service lives were estimated for the two most effective treatments. Asphalt Portland cement concrete composite (APCCC) was designed and evaluated, and compared with hot-mix asphalts and Portland cement concrete for strength properties, resistance to freeze-thaw and resistance to chloride intrusion. 248 pages. SHRP-S-666... 

Polymer concrete is a composite material formed by polymerising a monomer and aggregate mixture. There is no other cementitious material present in it. PPCC (or LMC) is a Portland cement concrete produced usually by replacing a specified portion of the mixing water with a latex (polymer emulsion). It can also be produced by adding a monomer to fresh concrete with subsequent in situ curing and polymerisation. PIC is a hardened Portland cement concrete with impregnated monomer which is polymerised in situ. 

Polymer concrete production uses equipment and methods that are being used for producing Portland cement concrete. In the design of polymer concrete mixes, the main objective is to obtain a suitable particle size distribution of the aggregate so that a good workability will be attained with a minimum amount of monomer or resin [9]. Aggregates should be dried to at least 3% moisture [11] but moisture contents less than 1% are preferred as moisture reduces the bond between the binder and the aggregate [14]. 

Applications of polymer mortars and polymer concretes include patching of Portland cement concrete, floor and pavement overlays, anti-corrosive linings, precast products, vaults, panels [8,11]. These indicate that there is no single polymer concrete that performs all of these tasks. Application and performance of polymer concrete depend on the binder used and the aggregate. Copolymerisation techniques allow the production of a wide range of binders with varying properties [11]. 

Polymer concrete can be placed by either premix, dry pack or prepack methods. The premix method is similar to the conventional Portland cement concrete mixing and placing. The binder, fine aggregate and coarse aggregate are added to the mixer in that order and mixing is continued until all aggregate particles are thoroughly wetted. Then the material is placed where it is required and consolidated. It is usually recommended that the surface to be treated is primed with the binder before placement. 

Overlays polymer concrete overlays are used to get a durable, almost impervious and wear-resistant surfaces on Portland cement concretes. Suitable surface texture may be obtained for appropriate skid resistance and hydroplaning characteristics. The surfaces on which overlay will be applied must be prepared to ensure good adhesion. The surface must be strong, sound, dry and clean. The monomer and aggregate systems used for polymer concrete overlays are similar to those of polymer concrete repairing materials. 

The method of producing precast polymer concrete is similar to that of precast Portland cement concrete. The extremely short hardening period of polymer concrete is an obvious advantage over Portland cement concrete. Form removal may be as short as 40 seconds, depending on the type of monomer used [11]. The formwork, vibrators and mixers used in producing polymer concrete precast elements are no different to those used for Portland cement concrete precast elements. Flowever, it should be noted that the formwork should be durable, smooth surfaced and must be able to withstand the heat developed during the exothermic polymerisation process. 

Portland cement concrete produced by replacing a specified portion of the mixing water with a latex (polymer emulsion). 

The design of polymer modified concretes is based on similar reasoning as for Portland cement concretes, but there are no published programs. In PCC, the binder is composed with two phases Portland cement and polymer phase that may be introduced to the mix as polymer latexes, and water-soluble polymers or liquid polymers. There is a continuous relation between PCC and PC when the polymer fraction (starting from 10% mass) is increased... 

Polymer-modified Portland cement concrete is normal concrete to which a synthetic resin has been added in the formulation. The same generic resins can be used that are used in polymer concretes. Properties of these two concretes differ, even when the same generic resin is used in both. 

While the polymer concrete may be totally chemical-resistant the comparable polymer modified Portland cement concrete is not, although certain benefits are derived including ... 

Polymer concretes are not the same as polymer modified Portland cement concrete. Polymer concretes are composed totally of synthetic resin compounds with fillers. They do not contain any Portland cement. Polymer-modified Portland cement concrete can use some of the same generic resins as used in polymer concretes, but with different results. 

Depending on the service, polymer concrete is cast in thicknesses from 1/2 in. (13 mm) to several inches, either with or without reinforcing. Cast-able polymer concretes are mixed and cast in a manner similar to that of Portland cement concrete, being poured into forms to harden. Troweled applications are generally thin coatings of less than 3/4 in. (20 mm) and are troweled in place with or without reinforcement. 

Creep deformation in the rPET polymer concrete systems examined in this study varied greatly depending on the type of filler. rPET polymer concrete generally undergoes lower creep deformation than Portland cement concrete. The polyester-based rPET polymer concrete was the only system with creep compliance higher than that of Portland cement concrete. 

Latex-modified concrete is conventional Portland cement concrete with the addition of a polymeric latex emulsion. The water of suspension in the emulsion hydrates the cement and the polymer provides supplementary binding properties to produce a concrete with a low water-cement ratio, good durability, good bonding characteristics and a high degree of resistance to penetration by chloride ions, all of which are desirable properties in a concrete overlay. 

---