Sand is a naturally occurring granular substance made up of tiny pieces of rock and mineral. Underrated is sand. It gives plaster structure, and the caliber of your sand will determine whether or not your project is successful. Hence, a good plaster sand should be clean, sharp, and have a range of particle sizes.
There are broadly two categories of river sand –
- Brown Sand
- Black Sand
River bottoms and the banks of rivers are where river sand is found. It has a very fine quality and is often brown and gray in hue. River sand is well-graded and suitable for all kinds of masonry and concrete projects.
The least expensive source of sand was the natural river sand. To fulfill the rising demand for sand in the building industry, however, excessive river bed mining has created an ecological imbalance and negatively impacted the ecosystem.
The specification for Sand for Plaster shall conform to IS 1542: 1992, which is given below as:
Quality of Sand:
Natural sand, crushed stone sand, crushed gravel sand, or any combination of these shall make up the sand. The sand must be tough, long-lasting, clean, free of organic matter and adhesive coatings, and it must not contain more clay, silt, or dust than what is indicated below.
Deleterious Materials:Any harmful impurities, such as iron pyrites, alkalis, salts, coal, mica, shale or similar laminated materials, soft fragments, sea shells, and organic impurities, shall not be present in the sand in such quantities as to adversely affect the hardening, the strength, the durability of the appearance of the plaster or apply decoration, or to cause corrosion of metal lathing or other metal in contact with the plaster.
Limits of Deleterious Materials:Unless found satisfactory after additional testing the engineer or architect may specify, or unless proof of such performance is provided that is agreeable to him, the maximum quantities of clay, fine silt, fine dust and organic impurities in the sand shall not exceed the following limits:
a) Clay, slit and dust [ determined in percent by weight accordance with IS 2386 ( Part 2 ): 1963]
Not more than 5 percent by weight
b) Organic impurities [ determined in accordance with IS 2386 ( Part 2 ) : 1963]
Color of liquid below that indicated by comparison with the standard solution specified in 6.2.2 of IS 2336 ( Part 2 ): 1963
The average compressive strength of mortar cubes made of one part cement and six parts sand that adhere to the gradation in Table 1 shall not be less than 3 N/mm2 at 28 days as determined by the standard procedure described in Appendix A of IS 2250: 1981.
According to IS 1727: 1967, the amount of water needed for gauging is the amount needed to produce a flow of between 110 and 115 with 25 drops in 15 seconds.
Grading of Sand:
As determined by the procedure established in IS 2386(Part 1): 1973, the particle size grading of sand for plaster work for internal and external walls and ceiling shall be as indicated in Table 1. It is considered to be within the grading when the grading is inside the grading zones of sieves other than the 150, 300, and 600 micron IS Sieve by a combined amount not exceeding 5 percent.
Table 1-Grading of Sand for Internal Wall or External Wall or Ceiling Plaster (As per IS 1542: 1992)
IS Sieve Designation ( See IS 460 : 1985 )
NOTE -The permitted limit on 150 micron IS Sieve has been raised to 20% for crushed stone sands and crushed gravel sands. The allowable 5% limit is unaffected by this.
In the case of crushed stone and crushed gravel sands, the fineness modulus must be at least 1.4, and in the case of naturally occurring sands, it must be at least 1.5.
The different sized particles that make up the sand must be evenly distributed throughout the mass.
The required grading can frequently be obtained by screening and/or combining crushed stone screenings or natural sands, which are both of the wrong grading on their own.
Sampling and Testing:
Sampling: The sample procedure must follow the guidelines in IS 2430: 1986. The amount of material required for each test shall be as indicated in relevant areas of IS 2386 and as per the requirements of mentioned earlier (1.Quality of Sand).
Testing:Every test that the buyer or his agent may request in relation to this standard must be completed in compliance with the guidelines set forth in the standard’s various clauses. Double tests must be conducted on every case, unless the inquiry or order specifies otherwise, and the findings of both tests must be recorded.
Note: For more information refer to IS 1542: 1992.
How to measure quality of sand on site
Excessive clay / Silt:-As clay makes sand more cohesive, high-quality sand should have less traces of clay.
Presence of excessive clay can be determined in two ways:-
- Take a glass of water and some sand to test for the presence of clay in the sand. Shake it a lot, then let the sand settle. Look to see if the sand has created an obvious layer. Less than 8% of a sand’s dry weight should be clay.
- Holding some dry sand, release it. If the sand sticks to your palm, clay is present.