With an unwavering commitment to quality control and because variations in quality have a great effect in industrial uses, Georgia-Pacific Gypsum ensures a high level of uniformity in every pound of gypsum we ship. Uniformity is an essential ingredient in all our industrial plasters. Customer satisfaction is our primary focus. We are dedicated to quality at every step of the way - from our mines to your molds and products.
The Manufacturing Cycle
The following description of mining and manufacturing processes demonstrates our commitment to quality.
At corporate-owned quarries and mines, gypsum is drilled and blasted from the excavation site. This process involves careful inspections of the excavation site, followed by precision undercutting and topcutting prior to blasting.
The rock is then transported to a crusher. Aside from reducing the gypsum to a manageable size, crushing may include a process that dries the rock to remove any free moisture. At this point, we conduct a select grading of rock (commonly known as land plaster).
The rock undergoes a fine grinding process prior to calcination, where the chemical composition of mined gypsum is transformed into a hemi-hydrate of calcium sulfate, making it suitable for commercial applications.
Depending on the calcination method, the resulting plaster exhibits distinct properties and characteristics that affect its suitability for specific applications. We are careful to follow quality standards that ensure our products always meet customer expectations for performance and purity-as well as our own stringent criteria for industry superiority.
Standard Testing Methods
Georgia-Pacific conducts physical tests of our products in accordance with appropriate ASTM standard specifications and test methods established for various characteristics. Some of these are described below:
|Fluidity||…is a designated water:plaster ratio referring to the extent to which the mixture can move and change shape without separating.|
|Consistency||…is expressed in cubic centimeters of water per hundred grams of plaster. Viscosity, strength and porosity are several of the important properties that can be accurately predicted from a slurry's consistency.|
|Setting Time||…is normally considered to be the elapsed time from the moment the plaster and water come in contact until the time when the setting plaster has the ability to support a determined weight.|
|Compressive Strength||…is the load-bearing capacity defined as pounds per square inch.|
|Screen analysis||…is either a dry or wash method, a test procedure for passing 25 or 50 grams of a sample through a sieve to determine particle size.|
|Setting Expansion||…is the dimensional stability of a plaster when setting. Low expansion is an important requisite for many applications.|
Quality Assurance Program
Toward this end, we have established a strict program of quality assurance throughout our mining and production processes. Each plant is equipped with an up-to-date laboratory operated by trained and experienced plant personnel.
All land plaster raw material must pass an incoming materials control test. Precision measurement equipment and weight scales are used to grade and qualify material during the steps prior to processing.
The ratio of water to gypsum is impacted by the calcination process. Separate and distinct calcination processes are used to produce the plaster desired.
At the mixing stage, consistency and set time expansion tests are conducted to ensure the highest levels of quality. Gypsum products can be greatly affected by small amounts of impurities. Both field lab tests and inspections ensure that the plasters being manufactured are in compliance with plant and customer specifications.
Meticulous sampling is conducted to guarantee the highest levels of consistency. All formulations, whether standard products or custom-blended to customer specifications, are carefully tested to ensure exact quantities of retardants, accelerators and any other additives. All production is dated and identified by batch coding, and samples are archived at plants for future reference.
Plant and laboratory personnel make frequent trips into the field to check the performance of all industrial plasters.