The ready availability of this gypsum cement, together with United States Gypsum Company’s nationwide distribution, makes HYDROCAL FGR a desirable substitute for higher priced products or those subject to short supply. 

Developed by United States Gypsum Company, this new technology consists of blending glass fibers with specially formulated HYDROCAL FGR Gypsum Cement.  The cement is mixed with  a small amount of water to make a slurry which can be sprayed simultaneously with chopped glass fibers to form glass-reinforced gypsum. 

HYDROCAL FGR sets fast, develops high strength and permits fabrication of strong, resilient glass-reinforced gypsum products that are fire resistant, adaptable to deep patterns, accept most coatings, help overcome fire-code problems of many plastics, and cost about 2/3 less than filled polyesters. 

FEATURES OF GLASS-REINFORCED GYPSUM USING HYDROCAL FGR GYPSUM CEMENT 

Fire Resistant  
Gypsum is a mineral.  It will not burn.  Laboratory fire tests conducted on varying thickness of HYDROCAL FGR Gypsum Cement (with 5% to 6% glass fiber content and without face coating) substantiate this noncombustibility, also show no appreciable fuel contribution and zero flame spread. 

The temperature of glass-reinforced gypsum will not exceed 212oF, until all chemically combined water is removed. 

Safety in handling 
Gypsum does not emit toxic gases when subjected to heat as some materials do.  Gypsum cement is nontoxic, nonallergenic and odorless.  It does not attract or support vermin and when dry does not support mold , fungus or bacteria.  Noncorrosive to most nonferrous materials and noncombustible, it requires only reasonable handling precautions.  With a pH of 6.5 to 8.0, it has a virtually neutral reaction. 
 
 
 
 
 
 
 
 
 
 

Saving to 70% 
Gypsum cement is a low-cost solution to those industrial product and process problems for which it is suited.  The cost of HYDROCAL FGR Gypsum Cement is about 70% less than most thermosetting plastics. 

Lightweight but strong 
Glass-reinforced gypsum panels (made from HYDROCAL FGR and glass fiber) 1/10 in. thick weigh only 9/10 lb. per sq. ft.  Test results show a flexural strength of 4,000 psi, flexural modulus 2.1 x 105 psi, impact strength 8.0 to 8.8 psi. 

Versatile paintability  
Glass-reinforced gypsum made from HYDROCAL FGR has a surface that’s easily decorated with most oil-base, alkyd or latex paints, and most stains, lacquers, varnishes or shellacs. 

Controllable setting time 
Easily controlled through the use of simple nontoxic accelerators or retarders, thus creating working time range of 10 min. to 2 hours.  Setting time is easily reproducible from batch to batch. 

Controllable setting expansion 
HYDROCAL FGR GYPSUM Cement expands during the setting action.  Expansion proceeds simultaneously with the setting process and is complete upon final set - normally about one hour after application.  Maximum expansion is 0.320% 

This expansion has numerous practical benefits, such as fidelity of detail, release of casts from drafted molds, and reproducible dimensional accuracy. 

Dimensional stability 

Gypsum cements are unaffected by normal changes in temperature and humidity. 

Dependable results 

Gypsum cements have a shelf life of three to six months and are buffered to a great degree against user variables.  With adherence to a new simple procedural control in the plant, good results are obtainable. 
  
 
 
 
 
 

TYPICAL PHYSICAL PROPERTIES - GLASS-REINFORCED GYPSUM 

Matrix  HYDROCAL FGR Gypsum Cement 
Consistency 25-30 cc. 
Glass Fiber 5-6% by weight Type E chopped to 1" length 
Flexural Strength 3200-4000 psi 
Modulus of Elasticity in Flexure 2.1-2.2 105 psi 
Ultimate Tensile Strength 1200-1400 psi 
Modulus of Elasticity in Tension 2.7-3.8 x 106 psi 
Impact Strength 8.0-8.8 ft. lb./in.2 *** 
Thermal Conductivity 4.0-4.2 Btu/hr.. ft.2 . oF . in. 
Specific Heat 0.253 Btu/lb. . oF. 
Flammability Zero flame spreadZero smoke contribution 
Rockwell Hardness M72 
Dielectric Strength Same as air when dry;conductive when wet 
Density 103-112 lb./ft.3 
Thermal Coefficient of Expansion 8.3 x 10-6in./in./oF. 
Coverage 100 lb. of HYDROCAL FGR GypsumCement 125 ft.2-1/10" thick 
***Modified Charpy method per ASTM D256-73 (Part 35) or ANSI No. C59.11;1974