Building lime is subjected to several laboratory tests to determine its suitability as a construction material. One such test is the consistency of putty. This test evaluates the workability of the lime putty by measuring its resistance to deformation. The consistency of the putty is a crucial factor in determining its suitability for use in construction works.
During the test, the lime putty is allowed to mature for a specific duration before measuring its consistency. The putty is considered mature when it develops a cohesive and plastic nature, which means it can be molded without cracking or breaking. Once the putty is mature, it is placed in a standard mold and subjected to a standard weight for a specified duration.
The amount of deformation of the putty caused by the weight is then measured, and this measurement determines the consistency of the putty. If the putty deforms too much under the weight, it is considered too soft, while too little deformation indicates a hard putty. An optimum amount of deformation shows that the putty has the right consistency for use in construction works.
In summary, the consistency of putty test is an essential evaluation of building lime’s workability. The test ensures that the lime putty has the right amount of resistance to deformation and can be easily molded without cracking or breaking. The test results help determine if the putty is suitable for use in construction works.
Laboratory Testing of Lime to be Used as a Building Material in Construction
Laboratory tests are performed to determine the suitability of lime as a building material. These tests include the Loss on Ignition (LOI) test, reactivity assessment of quicklime, rapid sugar test of lime, volume yield test of quicklime, and consistency test of putty. The LOI test measures the amount of carbon dioxide and water vapor released from lime when heated, which helps determine its purity. The reactivity assessment of quicklime assesses its ability to react with water and release heat, indicating its quality for construction purposes. The rapid sugar test of lime measures the time taken for lime to set when mixed with sugar, providing information on its setting characteristics. The volume yield test of quicklime measures the volume of hydrated lime obtained from a known weight of quicklime, determining its reactivity and quality. Lastly, the consistency test of putty evaluates the consistency and workability of lime putty, which is important for its use in building applications. These tests collectively help determine the suitability of lime as a building material based on its properties and performance characteristics.
Building lime undergoes various special tests in the laboratory. These tests are specifically designed to assess the quality and performance of building lime in construction applications. These special tests provide valuable information about the characteristics and properties of building lime, ensuring that it meets the required standards and specifications for use in construction projects. The results of these tests help determine the suitability of building lime for specific construction purposes and ensure its performance and durability in various environmental conditions. These special tests are essential in evaluating the quality and reliability of building lime and ensuring its safe and effective use in construction applications.
1. Loss on Ignition Test (LOI) on Building Lime
The loss of ignition test can be utilized to determine the relative degree of calcination in lime. In this process, a lime sample is subjected to high temperatures to eliminate any volatile substances present within it. As a result, there will be a change in the mass of the sample compared to its initial mass.
By conducting this test, it is possible to monitor the amount of calcination that has occurred in the lime. Calcination refers to the process of heating a material to a high temperature in the absence of air or oxygen. This process can cause the material to undergo various chemical and physical changes, depending on the temperature and the material’s properties.
The loss of ignition test helps to identify the extent of calcination that has occurred in the lime sample. The amount of mass loss that occurs during the heating process can provide an indication of the sample’s degree of calcination. This information can be useful in various industries, such as construction and agriculture, where lime is used as a soil amendment or building material.
The detailed loss of ignition of lime can be explained by the following steps in sequence:
A sample is provided and placed into a container called Tare II. The next step involves placing the Tare into a furnace that is temperature-controlled. The sample is then allowed to cool down in an atmosphere that is free from both water and carbon dioxide. Once the sample has reached a stable temperature, the mass of the final quantity is determined. It is important to note that to ensure the completeness of the mass change, the entire process can be repeated again.
2. The Reactivity Assessment of Quick Lime
Adding water to quicklime leads to the process of hydration, which releases a significant amount of heat, making it highly exothermic. The rate of hydration in quicklime can be determined by the degree of burning it has undergone. Quicklime that is lightly burned has a higher tendency to undergo fast rate hydration as compared to over-burned or hard quicklime. This phenomenon is utilized to monitor the reactivity and degree of burning of the quicklime.
The hydration process of quicklime is important as it helps to determine the extent of burning that the lime has undergone. Lightly burned quicklime has a higher reactivity and undergoes fast rate hydration when water is added to it, while over-burned quicklime or hard lime has a lower reactivity. The monitoring of reactivity and degree of burning of quicklime is important to ensure that it is of the required quality for various industrial applications.
The exothermic nature of the hydration process of quicklime makes it a useful tool for determining the degree of burning and reactivity of quicklime. It is important to note that the rate of hydration is dependent on the degree of burning, and quicklime that is lightly burned will have a higher rate of hydration. This information is utilized to determine the quality of quicklime, and to ensure that it meets the required standards for various industrial uses.
3. Rapid Sugar Test on Lime
The rapid sugar test is a method used to determine the amount of available lime in a sample. The procedure involves taking a 500mg sample of sieved hydrated lime and placing it in a flask containing 20ml of distilled water. The flask is then heated for two minutes and swirled before adding 150ml of water and 15g of granulated sugar. After recorking the flask, it is shaken at five-minute intervals and left undisturbed for one hour.
The next step in the procedure is titration, where the solution in the flask is titrated against a standard hydrochloric acid (HCl) solution with two drops of phenolphthalein. The titration is carried out using standard procedures, and the final reading is recorded. The conversion is based on the principle that 1ml of the acid solution represents an equivalent amount of available lime (CaO) in 1%.
4. Volume Yield of Quicklime
When conducting the volume yield test for quicklime in India, IS 6932-Part 6 standard codes are followed. The test involves mixing quicklime with water, in a ratio of three to four times the mass of quicklime, resulting in a chemical reaction that produces calcium hydroxide. This reaction generates a significant amount of heat and causes the mixture to boil. If the sample being tested is dolomite lime, magnesium hydroxide or oxide may also be produced.
The resulting product is a suspension of finely divided calcium hydroxide in water, also known as slaked lime. This product is then cooled and screened to make it suitable for use in construction. As the slaked lime mass cools, it stiffens to a required consistency, which facilitates its use during the construction process.
The yield of putty, which is typically 70 to 100 ft3, is dependent on the type of putty used, the degree of burning of the lime (lightly or over burnt), and the slaking conditions. Putty is primarily used in masonry mortar applications due to its plasticity and workability. The putty improves the mortar mix’s quality and facilitates the construction of masonry structures.
Consistency of Putty
The Southard viscometer is a measuring instrument that is utilized to adjust the consistency of putty. It consists of a metal cylinder with a diameter of 50mm that is mounted on a wooden platform. A close-fitting piston moves up and down within the cylinder without any turning or movement of the cylinder. The device has a working stroke of 65mm, and to measure the degree of slumping caused by the ejection of putty, a metal bridge is attached.
The instrument is supplied with a putty density vessel, and to measure the density of the putty, a filter cloth is folded into a bag and filled with sufficient putty. The bag is then suspended above the vessel by a chord, and the putty is allowed to drain. Applying moderate pressure to the bag can accelerate the draining process.
A slump of 13mm is desired, and the consistency of the putty must be adjusted to achieve this. The density of the putty can be determined by using the known volume of the putty and a density vessel. The formula used to calculate the volume of quicklime (ml) is 0.70/(d-1), where ‘d’ is the density of the lime putty.
Standard Equipment for Laboratory Tests on Building Lime
Laboratory tests on building lime typically rely on standardized equipment that is commonly used in the field. These tools and instruments have been developed over time to ensure accuracy, consistency, and reliability in measuring the properties and characteristics of lime-based materials.
Some of the most commonly used standard equipment for laboratory tests on building lime include devices for measuring the chemical composition of the material, such as X-ray fluorescence spectrometry (XRF) and atomic absorption spectroscopy (AAS). These tools allow researchers to determine the concentration of various elements present in the lime sample, providing valuable insights into its properties and potential uses.
Other essential equipment used in laboratory tests on building lime includes devices for measuring the physical properties of the material, such as particle size distribution analyzers, surface area analyzers, and thermal gravimetric analyzers. These instruments enable researchers to quantify aspects such as particle size, surface area, and thermal behavior, which are critical in assessing the performance of lime-based materials in various applications.
Overall, the standardized equipment used in laboratory tests on building lime plays a vital role in enabling researchers to accurately and reliably measure the properties and characteristics of these materials. By providing detailed insights into the chemical and physical properties of lime-based materials, this equipment helps to support the development of new products and technologies that can benefit a range of industries and applications.
1. Building Lime Mortar Mixer
The motor mixer is a device that is powered by electricity and has an epicyclical design. Its mixing bowl is made of stainless steel and has a capacity of 5 liters. The shape and size of the mixer can be seen in figure-1 and figure-2. To ensure safety during the mixing process, the bowl is designed to securely connect to the mixing stand. The mixing blade is engineered to rotate in a planetary motion within the bowl, and the motor facilitates this movement.
The mixing process begins at an initial slow speed of 140 ± 5rpm. This is followed by a planetary motion at a speed of 64 ± 5 rpm. The second speed is at a rate of 285 ± 10 rpm, with a planetary motion of 125rpm. The electric motor assembled for this mixer has a power of 150 W. During the mixing process, the mixer allows for adjustments to be made. This is important to maintain a minimum clearance of 2.5mm between the blade and the lower inner end of the mixing bowl. It is crucial that this clearance is not less than the diameter of the sand used for the mix.
Fig.1: Building Lime Mortar Mixer Bowl
Fig.2: Lime Mortar Mixer Blade
2. Standard Flow Table for Tests on Building Lime
The consistency and workability of mortars and building lime can be determined using a flow table, which comes in two forms: manual and motor-operated. The motor-operated flow table utilizes a motor speed reducer and has preset drops that allow it to end automatically at the end of each cycle. The arrangement includes a flow mold and tamping rods, and some arrangements may also include a filling hopper. The flow mold is a truncated conical shape and is used in conjunction with the tamping rods to determine the flowability of the material being tested. The motor-operated flow table arrangement is a convenient and efficient method for determining the consistency of mortars and building lime.
Fig.3: Diagram showing a standard flow table and a truncated conical flow mold