MATERIALS TESTE gypsum

The ASTM standard E96, Standard Test Method for Water Vapor Transmission of Materials provides a method for determination of water vapour transmission of materials such as paper, plastic films, other sheet materials, fibreboards, gypsum and plaster products, wood products, and plastics. This method has also been used for textiles for quite some time, although it does not simulate the actual wearing conditions of clothing. 

The gas permeability of the constructive materials after treatment by chemicals was examined. Influence of types of concrete, cement and gypsum, preliminary treatment by different chemicals, time between treatments by organic compounds, humidity of constructive materials, time between preparation of chemicals and treatment of materials (aging of chemicals), time between treatment of materials and testing (aging of treated materials) were investigated. 

Staff Portland Cement Plaster Stucco Manual, Portland Cement Association. Skokie, 1L. I99(i. hitpif/www.portccmcnl.org/index.usp Staff Anuiutl Book of ASTM Standards. 1997 Cement Lime Gypsum. American Society for Testing and Materials. West Conshnhocken. PA. 1997. http //www.ust nt.org/... 

Staff Cement, Lime, Gypsum, American Society for Testing Materials, West Conshohocken, PA, 2000. 

The softest mineral, talc, can be used in body powder. The hardest, diamond, is used in drill bits to cut through the most dense crustal materials. Mohs scale is a relative index scale, meaning that a determination of Mohs hardness number for a mineral is based upon scratch tests. For example, gypsum (Mohs hardness number = 2) will scratch talc (Mohs hardness number = 1). Talc, however, will not scratch gypsum. Glass is assigned a Mohs hardness number of 5.5 because it will scratch apatite (Mohs hardness number = 5) but will not scratch orthoclase feldspar (Mohs hardness number = 6). 

Figures 1,2, and 3 are provided to illustrate one protocol often used to evaluate sink materials [20,32,42-47] however, other methods are also used. For example, Krebs and Guo [48] reported on a unique method involving two test chambers in series. The first chamber is injected with a known concentration of a pollutant (in this case, ethylbenzene). The outlet from the first chamber provides a simple first-order decay that is injected into the inlet of the second chamber that contains the sink material (gypsum board). Thus, this method exposes the sink test material to a changing concentration typical of many wet VOC sources. The sink adsorption rate and desorption rate results are comparable to one-chamber tests and are achieved in a much shorter experimental time. Kjaer et al. [31] reported on using a CLIMPAC chamber and sensory evaluations coupled with gas chromatography retention times to evaluate desorption rates. Finally, Funaki et al. [49] used AD PAG chambers and exposed sink materials to known concentrations of formaldehyde and toluene and then desorbed the sinks using clean air. They reported adsorption rates as a percentage of concentration differences.

In order to address these questions and problems, this symposium was sponsored by ASTM Committee C-11 on Gypsum and Related Building Materials and Systems. The symposium was intended to provide a forum for discussions of theories, test methods and analyses, and basic information on gypsum and its products. 

REFERENCE Acker, R. E. Physical Testing of Gypsum Board Per ASTM C The Chemistry and Technology cf Gypsum, ASTM STP M/. R. A. Kuntze, Ed., American Society for Testing and Materials, i984, pp. 3-21. 

It is obvious that flexure tests should be directly proportional to specimen width. Numerous tests on both types of machines have confirmed this. The modulus of rupture (MOR) formula predicts that flexural strength should be inversely proportional to the span. Combining these relationships we can calculate that the test on the 12 by 16 specimen should be 12/10 X 10/14 = 0.857 times the strength of the 10 by 12 specimen. This is reasonably close to the slope of 0.8 found for the correlation equation. Gypsum wallboard is not a homogeneous material as is assumed in the calculation of MOR. 

Gardner. H. F., Notes on the Chemical and Microscopic Determinations of Gypsum and Anhydrite. Proceedings 26, Vol. I, American Society for Testing and Materials. Philadelphia. 1926. pp. 296. 

Precision of the test procedure is usually fair, with larger deviations for lower FSI figures. ASTM E 84-01 lists examples of FSI for six different materials, among them two samples of plywood (one was treated with flame retardant), one gypsum board, two plastic foams, and one composite panel. The determinations were made in eleven laboratories with four replicates of each material (Table 14.13). 

Fillers which were combined with sulfur included the principal clay minerals as well as diatomaceous earth, fly ash, and gypsum. These materials were generally combined singly with sulfur to facilitate the interpretation of results, but in some instances more than one was used. Trials were made to establish the filler proportions which could be mixed readily with the molten sulfur (130°C), and these designs were used to fabricate test specimens (Table II). 

The test samples were prepared by mixing the raw materials in different proportions. Water was added, in the amount of 30% by weight based on the total weight, to combine clay mixture. The clay mixture was soaked overnight to get a homogeneous mixture. The soaked mixture was then mechanically stirred and then kneaded by hands on the gypsum board. After the kneading, the clay... 

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