Sand is called fine aggregate because it is a granular material that is smaller in size than coarse aggregate and is typically defined as aggregate material that is smaller than 4.75 mm (3/16 inch) in diameter.
Sand Test List - Laboratory Test on Sand
Laboratory testing of sand is an essential step in determining its suitability for various construction applications. Sand is a naturally occurring material that is commonly used as a key component in the production of concrete, mortar and asphalt, among other construction materials. It is important to test sand in a laboratory setting to ensure that it meets the required specifications and standards for its intended use. This article will provide an overview of the laboratory tests performed on sand, the reasons for testing, and the equipment used.
Why Sand is Called Fine Aggregate?
Sand is called fine aggregate because it is a granular material that is smaller in size than coarse aggregate. Fine aggregate is typically defined as aggregate material that is smaller than 4.75 mm (3/16 inch) in diameter, and sand typically falls within this size range.
Fine aggregate, including sand, is an essential component of concrete, as it fills the voids between the larger coarse aggregate particles and helps to create a solid, strong, and durable concrete mixture. Sand is also used in other construction applications such as asphalt and masonry work.
The term "fine aggregate" is used to distinguish smaller aggregate materials from larger aggregate materials, which are called coarse aggregate. Coarse aggregate typically includes materials such as gravel, crushed stone, and recycled concrete, which are larger in size than fine aggregate and can range in size from 4.75 mm (3/16 inch) to several inches in diameter.
Sand Test List - Laboratory Test Sand
Laboratory testing of sand is necessary to ensure that it meets the required specifications and standards for its intended use. Sand that is unsuitable for construction purposes can lead to structural failure, erosion, and a host of other problems. Testing sand in a laboratory setting helps to identify its properties, including its grain size distribution, mineralogy, and strength characteristics, which are essential for determining its suitability for specific construction applications.
Laboratory Tests for Sand - Sand Test List
Grain Size Analysis (GSA):
Grain Size Analysis (GSA) is a laboratory test performed on sand to determine its particle size distribution. This test is critical in determining the suitability of sand for different construction applications, as it provides information on the sand's size and shape, which can affect its strength, stability and porosity.
The GSA test is performed using a set of sieves with different mesh sizes. A representative sample of sand is weighed, and then passed through a stack of sieves in descending order of mesh size. The sieves are agitated for a set period to ensure that all the particles have passed through. The weight of the sand retained on each sieve is then determined, and the percentage of sand in each size fraction is calculated.
The size of the sand particles is typically reported in terms of its grain size distribution curve, which is a plot of the percentage of sand that passes through each sieve against the corresponding sieve size. The curve can be used to determine the sand's grading and the particle size distribution, including the mean and standard deviation.
Grading of sand is classified based on the percentage of sand that passes through different sieve sizes. For instance, sand that has a uniform particle size distribution is classified as well-graded, while sand that contains a wide range of particle sizes is classified as poorly graded. The grading of sand can affect its workability, strength and porosity.
Also, the GSA test, other tests can be performed to supplement the information obtained from GSA, including the bulk density, specific gravity, and clay content tests. These tests provide information on the density and mineralogy of the sand, which can affect its compressive strength and durability.
In short, Grain Size Analysis is a crucial laboratory test that provides critical information on the particle size distribution of sand, which is essential in determining its suitability for different construction applications. The test can be performed using a set of sieves and provides information on the grading, particle size distribution, and mean particle size of sand. Other tests can be performed in combination with GSA to supplement the information obtained from the test.
Specific Gravity Test (SPG):
Specific Gravity (SPG) is a laboratory test performed on sand to determine its density in relation to the density of water. This test is important in determining the suitability of sand for construction applications, as it provides information on the sand's ability to support structural loads and its porosity.
The SPG test is performed using a specific gravity bottle filled with a known volume of water. A representative sample of sand is weighed and then placed into the bottle, which is filled with water until it overflows. The weight of the bottle, sand, and water is then determined, and the weight of the empty bottle and the weight of the water displaced by the sand are subtracted to obtain the weight of the sand. The specific gravity of the sand is then calculated by dividing the weight of the sand by the weight of an equal volume of water.
The specific gravity of sand typically ranges between 2.5 and 2.9, depending on the type of sand and its mineral content. Sands with a higher specific gravity are denser and can support higher structural loads, while sands with a lower specific gravity are more porous and can be more suitable for drainage and filtration applications.
Also, the SPG test, other tests can be performed to supplement the information obtained from SPG, including the grain size analysis, bulk density, and clay content tests. These tests provide information on the size, shape and mineralogy of the sand, which can affect its porosity and compressive strength.
In short, Specific Gravity is an important laboratory test that provides critical information on the density of sand in relation to the density of water, which is essential in determining its suitability for construction applications. The test can be performed using a specific gravity bottle and provides information on the sand's ability to support structural loads and its porosity. Other tests can be performed in combination with SPG to supplement the information obtained from the test.
Bulk Density Test (BD):
Bulk density (BD) is a laboratory test performed on sand to determine the density of a given volume of the sand, including the volume of the voids or spaces between the sand particles. The test is used to determine the weight per unit volume of a material, which is important in determining the amount of material required for a given construction project.
The bulk density test is performed by measuring the weight of a known volume of dry sand and then calculating the bulk density by dividing the weight by the volume. The volume can be determined by filling a container with the sand and measuring the volume of the sand and the voids using the displacement method, where a known amount of water is added to the container, and the change in water level is measured.
The bulk density of sand can vary depending on factors such as the size and shape of the sand particles, the degree of packing, and the moisture content. The density of dry sand ranges from 1.3 to 1.7 g/cm³, while the density of moist sand can range from 1.7 to 2.2 g/cm³. The bulk density of sand is also affected by the compaction effort applied during placement.
Also, the bulk density test, other tests can be performed to supplement the information obtained from the test, including the grain size analysis, specific gravity, and clay content tests. These tests provide information on the size, shape, and mineralogy of the sand, which can affect its packing and compressive strength.
In short, bulk density is an important laboratory test that provides critical information on the density of a given volume of sand, including the volume of the voids or spaces between the sand particles. The test can be performed using a container and the displacement method and provides information on the weight per unit volume of the sand. Other tests can be performed in combination with bulk density to supplement the information obtained from the test.
Silt Content of Sand:
Silt content is a laboratory test performed on sand to determine the amount of silt particles present in the sand. Silt particles are fine-grained particles that are smaller than sand particles but larger than clay particles. They can affect the workability and strength of sand and can lead to problems such as poor compaction, reduced shear strength, and increased settlement.
The silt content test is performed by passing a representative sample of sand through a series of sieves with decreasing mesh sizes. The sand that passes through the finest sieve is collected and mixed with water to form a suspension. The suspension is then allowed to settle, and the height of the settled silt layer is measured. The silt content is then calculated as the percentage of the weight of the dried silt to the weight of the original sand sample.
The amount of silt present in sand can vary, with different standards specifying different maximum limits.
For Example, the American Society for Testing and Materials (ASTM) standard D2419-14 limits the silt content of sand used for construction purposes to a maximum of 10%, while the CPWD in India, the limit is maximum of 8%.
Also, the silt content test, other tests can be performed to supplement the information obtained from the test, including the grain size analysis, specific gravity and clay content tests. These tests provide information on the size, shape and mineralogy of the sand, which can affect its workability, strength, and porosity.
In short, silt content is an important laboratory test that provides critical information on the amount of silt particles present in sand, which can affect its workability and strength. The test can be performed using a series of sieves and provides information on the percentage of silt present in the sand. Other tests can be performed in combination with silt content to supplement the information obtained from the test.
Organic Impurities Test:
Organic impurities are unwanted substances that can be present in sand and can affect the strength and durability of concrete made with that sand. Organic impurities may include decaying vegetable matter, peat, coal, and other organic materials. These impurities can interfere with the chemical reactions that occur during the curing process of concrete, leading to reduced strength and durability.
The organic impurities test is performed by adding a sample of sand to a solution of sodium hydroxide (NaOH) and water. The mixture is then boiled for five minutes and allowed to cool. The resulting color of the liquid is compared to a color chart to determine the presence and severity of organic impurities. The color of the liquid can range from light yellow to dark brown, with darker colors indicating a higher level of organic impurities.
The American Society for Testing and Materials (ASTM) standard C40 limits the organic impurities in fine aggregates, including sand, to a maximum of 2%. The Indian Standard Code (IS 2386) also specifies a limit of 5% for organic impurities in sand used for construction purposes.
Also, the organic impurities test, other tests can be performed to supplement the information obtained from the test, including the grain size analysis, specific gravity, and clay content tests. These tests provide information on the size, shape, and mineralogy of the sand, which can affect its workability, strength and porosity.
In short, organic impurities are an important consideration when testing sand for construction purposes. The organic impurities test provides critical information on the presence and severity of organic impurities in the sand, which can affect the strength and durability of concrete made with that sand. Other tests can be performed in combination with the organic impurities test to supplement the information obtained from the test.
Clay Content Test:
The clay content test is a laboratory test performed on sand to determine the amount of clay particles present in the sand. Clay particles are one of the smallest particle sizes in soil and can affect the workability, compressibility, and permeability of sand. The test is important because sand with a high clay content can lead to decreased strength and durability of concrete made with that sand.
The clay content test is performed by first drying a sample of sand in an oven and then weighing it. The sand is then mixed with water and a dispersing agent to break up the clay particles. The mixture is stirred and allowed to settle for a specified period, after which the water and clay mixture is decanted off, leaving behind the sand. The sand is then dried in an oven and weighed again. The difference in weight between the two measurements provides the weight of the clay particles in the sand.
The percentage of clay content in the sand is calculated by dividing the weight of the clay particles by the weight of the dry sand and multiplying the result by 100. The American Society for Testing and Materials (ASTM) standard C117 specifies a limit of 3% for the clay content in sand used for construction purposes.
Also, the clay content test, other tests can be performed to supplement the information obtained from the test, including the grain size analysis, specific gravity, and organic impurities tests. These tests provide information on the size, shape, and mineralogy of the sand, which can affect its workability, strength, and durability.
In short, the clay content test is an important laboratory test that provides critical information on the amount of clay particles present in sand. The test can be performed using a dispersing agent to break up the clay particles and is important in determining the workability, compressibility, and permeability of the sand. Other tests can be performed in combination with the clay content test to supplement the information obtained from the test.
Soundness Test on Sand:
Soundness is a measure of the durability of sand and its resistance to disintegration over time due to the effects of weathering, such as freeze-thaw cycles. The soundness test is performed to determine the resistance of sand to disintegration over repeated cycles of wetting and drying. The test is important because disintegration of sand can lead to the formation of voids and weaken the structure of concrete made with that sand.
The soundness test is performed by exposing a sample of sand to 5 cycles of wetting and drying. The sand is first dried in an oven and then immersed in a saturated solution of sodium or magnesium sulfate. The sand is then placed in an oven and heated to a temperature of 110°C (230°F) for 24 hours, after which it is allowed to cool and dry. This process is repeated 5 times, and the sand is then sieved to determine the percentage of material that has disintegrated.
The percentage of disintegration is calculated by subtracting the weight of the material that remains after the test from the initial weight of the sand sample and dividing the result by the initial weight of the sand sample. The American Society for Testing and Materials (ASTM) standard C88 specifies a maximum limit of 10% for the disintegration of sand in the soundness test.
Also, to the soundness test, other tests can be performed to supplement the information obtained from the test, including the grain size analysis, specific gravity, and clay content tests. These tests provide information on the size, shape, and mineralogy of the sand, which can affect its workability, strength, and durability.
In short, the soundness test is an important laboratory test that provides critical information on the resistance of sand to disintegration over repeated cycles of wetting and drying. The test is important in determining the durability of sand and its suitability for use in concrete. Other tests can be performed in combination with the soundness test to supplement the information obtained from the test.
Fineness Modulus (FM):
Fineness modulus (FM) is a measure of the average size of sand particles in a sample of sand. The FM is calculated by adding together the percentages of sand particles in each of the standard size ranges (or sieves) and dividing the total by 100. The size ranges used in the calculation are typically the sieve sizes that pass 100%, 50%, and 30% of the sand sample.
The FM of sand is important because it can affect the workability, strength, and durability of concrete made with that sand. Sand with a high FM is generally considered to be coarser and may require more water to achieve the desired workability of concrete. Sand with a low FM is generally considered to be finer and may result in concrete with a smoother surface finish.
The FM test is performed by sieving a sample of sand through a set of sieves with different size openings. The weight of sand retained on each sieve is then recorded, and the percentage of sand particles in each size range is calculated. The FM is then calculated by adding together the percentages of sand particles in each of the standard size ranges and dividing the total by 100.
The American Society for Testing and Materials (ASTM) standard C33 specifies a range of FM values for sand used in concrete, depending on the desired strength and workability of the concrete. For example, a FM range of 2.3-3.1 is recommended for concrete with a compressive strength of 20-40 MPa (3000-6000 psi), while a FM range of 2.5-3.5 is recommended for concrete with a compressive strength of 40-70 MPa (6000-10000 psi).
The Bureau of Indian Standards (BIS) has specified the range of fineness modulus (FM) values for different types of sand used in construction in India in the code of practice IS 383:2016 "Coarse and Fine Aggregates for Concrete - Specification".
The FM range for fine sand (Zone I) is 2.2-2.6, for medium sand (Zone II) is 2.6-2.9, and for coarse sand (Zone III) is 2.9-3.2. The code also specifies that the FM of sand should be within the limits specified for the respective zones, and the FM should not vary by more than 0.2 from the specified value.
Also, the FM test, other tests can be performed to supplement the information obtained from the test, including the specific gravity, clay content, and organic impurities tests. These tests provide information on the density, mineralogy, and contaminants present in the sand, which can affect its workability, strength, and durability.
In short, the FM test is an important laboratory test that provides critical information on the average size of sand particles in a sample of sand. The FM is an important factor in determining the workability, strength, and durability of concrete made with that sand. Other tests can be performed in combination with the FM test to supplement the information obtained from the test.
Alkali Aggregate Reactivity Test on Sand:
Alkali Aggregate Reactivity (AAR) is a chemical reaction that can occur between the alkalis (sodium and potassium) in cement and certain types of aggregates in concrete. This reaction can cause the expansion and cracking of concrete over time, which can lead to significant structural damage. To prevent this, it is important to test aggregates, including sand, for their potential to cause AAR.
The AAR test on sand is typically conducted using the mortar bar method, which involves casting mortar bars containing the sand to be tested and then exposing them to a solution of sodium hydroxide (NaOH) at a controlled temperature and humidity for a period of time. The degree of expansion of the bars is then measured and compared to a control sample to determine the potential for AAR.
The AAR test on sand can be performed using different methods, including the ASTM C1260 and ASTM C1567 tests. The ASTM C1260 test method involves casting mortar bars with sand and exposing them to a 1N NaOH solution at 80°C for 14 days. The ASTM C1567 test method involves casting mortar bars with sand and exposing them to a 1N NaOH solution at 38°C for 56 days.
The AAR test on sand can also be performed using different criteria for interpreting the results. The ASTM C1260 test method uses a pass/fail criterion based on the percentage of expansion of the mortar bars. A result of less than 0.10% expansion is considered a pass, while a result of 0.10% or greater expansion is considered a fail. The ASTM C1567 test method uses a modified version of the expansion criteria specified in the ASTM C1260 test method.
It is important to note that the AAR test on sand is just one of the methods used to assess the potential for AAR in concrete. Other tests, such as petrographic examination, can also be used to identify potential reactive aggregates. In addition, preventive measures such as the use of low-alkali cement or non-reactive aggregates can be taken to minimize the risk of AAR in concrete.
IS 2386 Part 7 is the Indian Standard code of practice for the test for aggregates for concrete - Part 7: Alkali Aggregate Reactivity (AAR) test for aggregates. This code specifies the procedure for conducting the AAR test on aggregates, including sand, in India.
The AAR test on sand as per IS 2386 Part 7 involves casting mortar bars containing the sand to be tested and then exposing them to a 1N solution of sodium hydroxide (NaOH) at 80°C for 14 days. After exposure, the length of the bars is measured, and the degree of expansion is calculated as a percentage of the initial length of the bars.
The code specifies that the maximum permissible expansion of the mortar bars should not exceed 0.10% for sand samples that are classified as non-reactive and 0.05% for sand samples that are classified as potentially reactive. The classification of sand as reactive or non-reactive is based on the expansion of the mortar bars relative to a control sample.
The test procedure in IS 2386 Part 7 also includes requirements for the preparation of the mortar bars, the equipment to be used, and the environmental conditions during the test. The code specifies that the test should be performed on at least three replicate samples of the sand, and the results should be reported as the average expansion of the mortar bars.
It is important to note that the AAR test on sand as per IS 2386 Part 7 is just one of the methods used to assess the potential for AAR in concrete. Other tests, such as petrographic examination, can also be used to identify potential reactive aggregates.
In short, the AAR test on sand is an important laboratory test that helps to determine the potential for alkali-aggregate reactivity in concrete. The results of this test can be used to select suitable aggregates for use in concrete and to take preventive measures to minimize the risk of AAR.
Relative Density of Sand:
The relative density of sand is the ratio of the density of the sand particles to the density of a reference substance. The reference substance used for determining the relative density of sand is typically water, and the test is known as the relative density test or the specific gravity test.
The relative density of sand can be determined by the following procedure:
Obtain a clean, dry container and weigh it.
Fill the container with a known weight of sand and weigh the filled container.
Add enough water to the container to cover the sand and weigh the container again.
Determine the weight of water added to the container by subtracting the weight of the filled container from the weight of the filled container with water.
Calculate the relative density of the sand using the following formula:
Relative density = (weight of sand in air / (weight of sand in air - weight of water added))
The relative density of sand typically falls within the range of 2.2 to 2.8, depending on the type of sand and the specific conditions of the test.
The relative density of sand is an important parameter in determining the properties of concrete, as it can affect the workability, strength, and durability of the concrete mixture. For example, sand with a higher relative density can result in a higher concrete strength due to the increased particle packing and reduced porosity.
What are Zones of Sand, Why Sand is divided into different Zones?
Sand is divided into different zones based on its particle size distribution. The particle size distribution of sand determines its suitability for use in various construction applications, such as concrete, mortar, plastering, and masonry work.
The classification of sand into different zones is based on the Indian Standard (IS) code of practice for the test for aggregates for concrete - Part 1: Particle size and shape. This standard divides sand into four zones, namely Zone I, Zone II, Zone III, and Zone IV, based on the percentage passing through various sieves.
The different zones of sand have varying proportions of fine and coarse particles, as well as varying fineness modulus, which is a measure of the particle size distribution of sand. The different zones of sand have different properties that make them suitable for different applications.
Zone I sand has a higher proportion of fine particles and is suitable for use in plastering and finishing work, as it results in a smoother surface finish.
Zone II sand has a balanced proportion of fine and coarse particles and is suitable for use in concrete and masonry work, as it provides good workability and strength.
Zone III sand has a higher proportion of coarse particles and is suitable for use in concrete for non-structural purposes, such as paving and road construction.
Zone IV sand has the highest proportion of coarse particles and is suitable for use in concrete for very specific purposes, such as for the construction of dams, bridges, and heavy-duty structures.
The division of sand into different zones helps ensure that the right type of sand is used for specific construction applications, which can help improve the strength, durability, and workability of the finished product. The use of the appropriate zone of sand can also help reduce the cost of construction and improve the overall quality of the finished structure.
