Mortars are used in construction as bonding agents for various building materials. Consistency is important to determine consistency and to assess the flow and performance of the mortar. In cement testing, mortar flow is tested using flow table test which gives us valuable information about the behavior of the mortar mix. This article will give you an overview of mortar flow in cement testing, key terms and concepts related to flow table test, mortars and associated test methods.
Cement Mortars: Cement mortars are mixtures of cement, sand and water used for various construction applications. These mixtures are made of hydraulic cement such as Portland cement, masonry cement or normal concrete which provides binding properties and strength to the mortar. Hydraulic cement mortars are tested for their flow properties using flow table. The proportion of cement, sand and water and water-cement ratio affects the flow of mortar.
Flow Table Test: Flow table test is a standard test method to determine the flow of cement mortars. It involves use of flow table, a motorized device that provides rotational motion to a flat circular platform. During the test, a test specimen of cement mortar is placed on the flow table and the platform is rotated at a specified speed. The flow value which is the diameter of the mortar spread is measured after a certain number of rotations.
Test Procedure: To perform the flow table test, a test specimen is prepared by mixing the cement, sand and all the mixing water in a mixing bowl. The water required for the mortar is determined based on the desired water-cement ratio. The mixing operation should be done for a specific time to ensure proper blending of the ingredients. Once the mortar is mixed, it is placed on the flow table in a pedestal form and compacted using a tamping rod. The motorized flow table is then set at a specified speed (medium or slow) and rotated for a specific time (1 minute). After rotation, the flow value is measured by sawing the mortar in a direction perpendicular to the flow.
Flow Value and Workability: Flow value obtained from flow table test gives an idea of workability and consistency of cement mortar. Higher flow value means more fluid and workable mortar and lower value means stiffer and less workable mixture. Flow value is affected by water-cement ratio, type and quantity of sand and presence of admixtures.
Compressive Strength Test and Drying Shrinkage Test: Besides flow table test, cement mortars undergoes various other tests to evaluate their performance. Compressive strength test measures the mortar’s ability to withstand loads and is done according to standardized procedures like ASTM C1437. Drying shrinkage test measures the dimensional changes in the mortar due to moisture loss and gives us idea about the stability and durability of the mortar. Researchers have carried out experiments following ASTM C standards to assess the properties of mortar during the drying process.
Mixing Water and Water-Cement Ratio: Amount of water added during mixing has significant effect on flow and workability of cement mortars. Water-cement ratio which is the ratio of weight of water to weight of cement in the mixture is a critical parameter to determine the properties of mortar. Water-cement ratio should be controlled carefully to get the desired flow value while maintaining sufficient strength and durability.
Mixing Process and Equipment: Mixing of cement mortars can be done by various methods and equipment. Mechanical mixers like paddle mixers or mortar mixers are commonly used to ensure uniform blending of the ingredients. Mixing process involves adding cement, sand and water in specific quantities to the mixing bowl and mixing until a homogeneous mixture is obtained. Mixing time and speed should be consistent to get reliable and repeatable results.
Test Specimens and Samples: During flow table test, test specimens of cement mortars are prepared and tested for flow value. These specimens are prepared in batches and mortar is poured in layers into a mould. Each layer is compacted using a tamping rod to remove air voids and ensure uniform distribution. Number of layers and compaction may be limited as per standard or requirement.
Significance and Interpretation of Results: Flow value obtained from flow table test gives valuable information about workability and consistency of cement mortars. It is an important parameter for quality control and material assessment. Results can be compared with specified flow value or standard to see if the mortar meets the requirement. Deviation from specified flow value may indicate need to adjust the mix proportions or further testing.
Flow of cement mortar is a critical property which affects its workability and application in construction. Flow table test is a standardized method to evaluate the flow characteristics of cement mortars. By understanding the key terms and concepts related to cement testing, flow table test and properties of cement mortars, professionals can get consistent and reliable results in their assessment of mortar workability, strength and durability.
A flow table test is a standardized method used to determine the workability and consistency of cement mortars. This test is crucial in the construction industry as it evaluates the flow characteristics of cement mortars, which are essential for various construction applications. During the flow table test, a specified amount of cement, standard sand, and water are mixed to create a mortar. This mixture is then placed on a flow table, which is dropped from a specified height at regular intervals. The test measures the spread of the mortar, providing valuable insights into its behavior. The flow value, which is the diameter of the mortar spread, is a key parameter in determining the workability and consistency of the mortar.
Flow table test requires meticulous preparation and attention to detail to get accurate results. This test is to evaluate the workability of cement mortar by measuring its flow. Here’s how to do it:
Prepare the Test Specimen: Mix cement, standard sand and water in specific ratio to get the mortar. Make sure all the mixing water is added to get the desired consistency.
Place the Mortar on the Flow Table: Once the mortar is prepared, place it on the flow table. Use tamping rod to compact the mortar to ensure it is evenly distributed and free of air voids.
Set the Motorized Flow Table: Adjust the motorized flow table to medium speed or slow speed and set the rotation time. This ensures the test conditions are consistent and repeatable.
Allow the Mortar to Flow: Start the flow table and let the mortar flow. The rotational motion will spread the mortar outwards.
Measure the Increase in Diameter: After the specified rotation time, measure the increase in the average base diameter of the mortar spread.
Calculate the Flow Value: Use the formula Flow = [(Davg – Do) / Do]*100 to calculate the flow value, where Davg is the average diameter after the test and Do is the original diameter. The flow value, which is the diameter of the mortar spread, is measured after a certain number of rotations, providing critical flow values for evaluating the workability of the mortar.
By following these steps you can get the workability of cement mortar using flow table test.
To do the flow table test effectively, specific equipment and accessories are required. These tools ensure the test is done accurately and consistently. Here are the necessary items:
Motorized Flow Table: This device provides the rotational motion to a flat circular platform so the mortar can spread and flow.
Flow Mold: A mold to shape the mortar into a specific form before it is placed on the flow table. It helps in measuring the flow characteristics of cement pastes and hydraulic cement mortars.
Tamping Rod: A rod to compact the mortar on the flow table to ensure it is evenly distributed and free of air voids.
Standard Sand: A specific type of sand used in the mortar mix to ensure consistency and reliability of the test results.
Cement: Hydraulic cement or masonry cement to bind the sand and water in the mortar mix.
Water: All the mixing water required to get the desired consistency of the mortar.
Using the right equipment and accessories is important to get accurate and reliable results in flow table test.
Flow table test requires several steps to measure the mortar’s flow characteristics accurately. Here’s how to do it:
Prepare the Test Specimen: Mix cement, sand and water in specific ratio to get the mortar, make sure all the mixing water is added to get the desired consistency. Mix thoroughly to get a homogeneous mixture.
Place the Mortar on the Flow Table: Transfer the prepared mortar to the flow table. Use tamping rod to compact the mortar to remove air voids.
Set the Motorized Flow Table: Adjust the motorized flow table to medium speed or slow speed and set the rotation time. This ensures the test conditions are consistent and repeatable.
Allow the Mortar to Flow: Start the flow table and let the mortar flow.
Measure the Spread: After the specified number of rotations, measure the increase in the diameter of the mortar spread.
Calculate the Flow: Use the formula Flow = [(Davg – Do) / Do]*100 to calculate the flow, where Davg is the average diameter after the test and Do is the original diameter.
Record the Flow: Record the flow to get the workability of cement mortar.
By following this you can do the flow table test accurately and get the reliable data of mortar workability.
Flow table test provides valuable information about the workability and consistency of cement mortars. The results can be compared with specified flow value requirements or standards to check if the mortar meets the desired criteria. Deviation from specified flow value may indicate need of mix proportion adjustment or further testing.
Flow value obtained from flow table test is an important parameter for quality control and material assessment. It gives an indication of workability and consistency of cement mortar which is important for various construction applications. Flow value is influenced by water-cement ratio, type and quantity of sand and presence of admixtures.
To interpret the result of flow table test follow these steps:
Compare the Flow: Compare the flow value obtained from the test with the specified flow value requirements or standards. This will help to check if the mortar meets the desired criteria for workability and consistency.
Check Consistency: Assess the consistency of cement mortar based on the flow value. Higher flow value means more fluid and workable mortar and lower flow value means stiffer mixture.
Check Compliance: Check if the mortar meets the desired criteria for workability and consistency. If the flow value is within the specified range then the mortar is compliant.
Identify Deviation: Look for any deviation from the specified flow value. Significant deviation may indicate mix proportion issue or need of further testing.
Optimize the Mixing: Use the result of flow table test to optimize the mixing process. Adjust the water-cement ratio, sand quantity or admixtures to get the desired flow value and ensure consistent quality. By reading the result of flow table test carefully professionals can ensure the cement mortar used in construction projects meets the required standards for workability and consistency. This is essential for getting reliable and durable construction results.
Flow table test is governed by several standards set by international and national organizations. International Organization for Standardization (ISO) and American Society for Testing and Materials (ASTM) have established guidelines for this test. ASTM C1437 is the standard test method for flow table test and provides detailed procedure to ensure consistency and accuracy. IS:4031(Part-7):1988 is also a national standard which details the methods for physical tests for hydraulic cement. These standards ensure the flow table test is conducted uniformly in different laboratories and construction sites and gives reliable and comparable results. Compressive strength of masonry cement is also evaluated as per ASTM standards.
Flow value is the key to determine the workability of cement mortar. It is calculated by the formula: Flow = [(Davg – Do) / Do]*100 where Davg is the average diameter of the mortar spread after the test and Do is the original diameter. Flow value is expressed as percentage of the original base diameter.
Flow table test result will give you valuable information about the mortar workability. Higher flow value means more fluid and workable mortar which is easy to apply and spread. Lower flow value means stiffer and less workable mixture which may require mix proportion adjustment or further testing.
Flow table test has wide range of applications in construction industry. It is used to evaluate the workability and consistency of cement mortars which is essential for quality and performance of masonry work. Understanding the relationship between pore characteristics and flow properties of mortar is necessary for accurate assessment. Also it helps in determining the compressive strength of masonry cement and drying shrinkage of hydraulic cement. But flow table test also has limitations. It requires special equipment and skilled personnel to conduct the test accurately. Also it may not be suitable for all types of cement mortars as results can be influenced by factors like type and quantity of sand, water-cement ratio and presence of admixtures. So while flow table test is a useful tool it should be used along with other testing methods to get comprehensive understanding of mortar properties.
Flow table test is one of the methods to evaluate the workability of cement mortars. Other common workability tests are slump test, V-funnel test and squeeze flow test. Each of these tests has its own methodology and application. Slump test is widely used for concrete and measures the vertical slump of a concrete cone. V-funnel test is used for self-compacting concrete and measures the time taken for the concrete to flow through a funnel. Squeeze flow test is used for high performance concrete and measures the spread of the concrete under a specified load. While flow table test is preferred for its simplicity and accuracy for cement mortars it may not be suitable for all types of mixtures. So selecting the right workability test depends on the project requirements and type of material being tested.
Flow table test is the method to determine the workability of cement mortar. By giving a standardized way of measuring the flow value this test ensures the consistency and reliability of mortar used in construction. Proper procedure and right equipment is necessary to get the reliable results. Flow table test is widely used in construction industry for quality control and material testing, hence it is must have tool for professionals working with cement mortars.
Oops, something went wrong. Please try again.
You are now logged in!
