It is very important to check the quality of sand on construction site. Bad quality of sand can impact the quality of concrete.
Sand is one of the most important constituents of concrete. The main purpose of adding sand (fine aggregate) to concrete is to fill the gaps between coarse aggregates. Then fill the gaps between the fine aggregates with cement. Sand fills concrete and improves its workability.
Sand is formed by the weathering of rocks. Well, depending on the region, different sands (pit sand, river sand, sea sand) are used, depending on their availability in construction. Good fine aggregate used in construction should be well screened (all particles are approximately the same size).
Fine aggregate used in construction should pass through a 4.75 mm sieve and be retained in a 150 micron sieve.
The tests listed below are simple tests that can be performed immediately on site to determine sand quality. These tests involve investigating sand properties that affect strength and quality.
Table of Contents
Different Types of Tests to Measure the Sand Quality on Construction Site
1. Excess clay/silt:-
If the sand contains clay, it will clump together, and good quality sand will have fewer traces of clay.
The presence of excess clay can be determined in two ways:
- To find out if sand contains clay, add it to a glass of water. Shake vigorously to settle the sand. Check to see if a visible layer has formed on top of the sand. Good quality sand should contain less than 8% clay.
- Drop it with dry sand. If the sand sticks to your palm, it’s clay.
2. Presence of organic impurities in sand:-
For the detection of organic impurities in fine aggregates. Take a sample of sand and add it to a sodium hydroxide [NaOH] solution. Stir the solution for a few minutes. If the color of the solution turns brown, the sand contains organic impurities that are unsuitable for construction. Good quality sand will lighten when mixed with a NaOH solution.
3. Presence of excessive moisture content/sand accumulation:-
Excess moisture in the sand will increase the volume of the sand. Fine aggregates with a volumetric moisture content greater than 5% are not suitable for building applications. For large projects, modulus testing and silt content by weight are recommended for accurate conclusions.