How to make sure your plastering project is a success.

Sand for Plaster

Sand is a naturally occurring granular material composed of finely divided rock and mineral particles. It provides the structure of plaster, and the quality of your sand can make the difference between success and failure. So, a good plaster sand should be sharp, with a diversity of particle sizes, and as clean as possible.

Quality of Sand:

The sand shall consist of natural sand, crushed stone sand or crushed gravel sand or a combination of any of these. The sand shall be hard, durable, clean and free from adherent coatings and organic matter and shall not contain clay, silt and dust more than a specified amount mentioned below.

Deleterious Materials: The sand shall not contain any harmful impurities, such as, iron pyrites, alkalies, salts, coal, mica, shale or similar laminated materials, soft fragments, sea shells and organic impurities in such quantities as to affect adversely the hardening, the strength, the durability of the appearance of the plaster or applies decoration, or to cause corrosion of metal lathing or other metal in contact with the plaster.

Limits of Deleterious Materials: Unless found satisfactory as a result of further tests as may be specified by the engineer or architect, or unless evidence of such performance is offered which is satisfactory to him, the maximum quantities of clay, fine silt, fine dust and organic impurities in the sand shall not exceed the following limits:

The average compressive strength, determined by the standard procedure detailed in Appendix A of IS 2250: 1981, of mortar cubes composed of one part of cement and six parts of sand conforming to gradation in Table 1 shall be not less than 3 N/mm2 at 28 days.

The amount of water for gauging shall be that required to give a flow between 110 to 115 with 25 drops in 15 seconds, as determined in IS 1727: 1967.

Grading of Sand

The particle size grading of sand for plaster work for internal as well as external walls and ceiling as analyzed by the method described in IS 2386(Part 1): 1973 shall be as specified in Table 1. Where the grading falls outside the limits of the grading zones of sieves other than 150, 300 and 600 micron IS Sieve by a total amount not exceeding 5 percent, it shall be regarded as falling within the grading.

Table 1-Grading of Sand for Internal Wall or External Wall or Ceiling Plaster (As per IS 1542: 1992):

NOTE – For crushed stone sands and crushed gravel sands, the permissible limit on 150 micron IS Sieve is increased to 20 percent. This does not affect the 5% allowance permitted.
The fineness modulus of sand shall be not less than 1.4 in case of crushed stone sands and crushed gravel sands and not less than 1.5 in case of naturally occurring sands.
The various sizes of particles of which the sand is composed shall be uniformly distributed throughout the mass.

The required grading may often be obtained by screening and/or by blending together either natural sands or crushed stone screenings, which are by themselves of unsuitable grading.

Sampling and Testing

Sampling: The method of sampling shall be in accordance with IS 2430: 1986. The amount of material required for each test shall be as specified in relevant parts of IS 2386 and as per the requirements of mentioned earlier (Quality of Sand).

Testing: Any test which the purchaser or his representative may require in connection with this standard shall be carried out in accordance with the provisions of various clauses in the standard. Unless otherwise stated in the enquiry or order, duplicate tests shall be made to all cases and the results of both tests reported.

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© 2016 Indian Institute of Technology, Kanpur

Note: For more information refer to IS 1542: 1992.

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