SPECIFICATIONS FOR CEMENT The following are the standard specifications of the American Society for Testing Materials,* and have been approved by the American Railway Engineering and Maintenance of Way Associa tion, and by the American Society of Civil Engineers. The headings and the numbering of the paragraphs are as in the original.
1. These remarks have been prepared with a view of poihting out the pertinent features of the various requirements and the precautions to be observed in the interpretation of the results of the teats.
2. The Committee would suggest that the acceptance or rejection under these specifications be based on tests made by an experienced person having the proper means for making the tests.
S. Speciflc Gravity. Specific gravity is useful in detecting adulteration. The results of tests of specific gravity are not necessarily conclusive as an indi cation of the quality of a cement, but when in combination with the results of other tests may afford valuable indications.
4. Fineness. The sieves should be kept thoroughly dry.
5. Time of Setting. Great care should be exercised to maintain the teat pieces under as uniform conditions as possible. A sudden change or wide range of temperature in the room in which the tests are made, a very dry or humid atmosphere, and other irregularities vitally affect the rate of setting.
6. Tensile Strength. Each consumer must fix the minimum requirements for tensile strength to suit his own conditions. They shall, however, be within the limits stated.
7. Constancy of Volume. The tests for constancy of volume are divided into two classes, the first normal, the second accelerated. The latter should be re garded as a precautionary test only, and not infallible. So many conditions enter into the making and interpreting of it that it should be used with extreme care.
8. In making the pats the greatest care should be exercised to avoid initial strains due to moulding or to too rapid drying-out during the first twenty-four hours. The pats should be preserved under the most uniform conditions pos sible, and rapid changes of temperature should be avoided.
9 The failure to meet the requirements of the accelerated tests need not be sufficient cause for rejection. The cement may, however, be held for twenty eight days, and a retest be made at the end of that period, using a new sample. Failure to meet the requirements at this time should be considered sufficient cause for rejection, although in the present state of our knowledge it can not be said that such failure necessarily indicates unsoundness, nor can the Dement be oonaidered entirely satisfactory simply because it passes the tests.
1. General Conditions. All cement shall be inspected.
2. Cement may be inspected either at the place of manufacture or on the work.
3. In order to allow ample time for inspecting and testing, the cement should be stored in a suitable weather-tight building having the floor properly blocked or raised from the ground.
4. The cement shall be stored in such a manner as to permit easy access for proper inspection and identification of each shipment.
5. Every facility shall be provided by the contractor and a period of at least twelve days allowed for the inspection and necessary testa 6. Cement shall be delivered in suitable packages with the brand and name of the manufacturer plainly marked thereon.
7. A bag of cement shall contain 94 pounds of cement net. Each barrel of portland cement shall contain 4 bags, and each barrel of natural cement shall contain 3 bags of the above net weight.
8. Cement failing to meet the seven-day requirements may be held awaiting the results of the twenty-eight-day tests before rejection.
9. All tests shall be made in accordance with the methods proposed by the Committee on Uniform Tests of Cement of the American Society of Civil Engi nears, presented to the Society January 21, 1903, and amended January 20, 1904 and January 15, 1908. [The methods described in Chapter IV are substantially in accordance with that report.] 10. The acceptance or rejection shall be based on the following requirements: