An overview of hydraulic cement and related IS codes for a construction quality engineer to refer
What is Hydraulic Cement and how to use it in construction works?
Hydraulic cement is the most extensively used material in all civil engineering works.
As per the definition given in the IS code, Hydraulic cement is a finely ground material which in addition to a requisite quantity of water is capable of hardening both underwater and in the air by the chemical interaction of its constituents with water, and is also capable of bending together appropriate materials.
IS Codes on Hydraulic Cement
1. IS 4845
The IS 4845:1968 gives the definitions and the list of terminology related to hydraulic cement
There are 8 distinct types of hydraulic cement as mentioned below:
Portland cement - used in ordinary construction works.
Cement containing blast furnace slag- as a substitute to ordinary cement in RMC construction
High alumina cement - used for sewers, chimneys, boilers, and kilns
Cement containing pozzolana - mass concreting works such as dams and canals
Masonry cement - for masonry works
Oil well cement - used under high pressure and temperature in sealing water and setting casings during the drilling and repairs of oil wells
Sulphate resistant cement - used in underground, sea shore structures
Hydrophobic cement - used in extremely wet climatic conditions.
This IS code is a go-to resource for terms related to hydraulic cement.
2. IS 3535:1986
IS 3535 is the code for the methods of sampling hydraulic cement. The methods for sampling and the criteria for conformity of hydraulic cement from bags, bulk storage ( silos ), ship’s hold, wagons, and conveyors. Broad outlines with regard to the controls to be exercised during the manufacturing process come under the scope of this IS code.
This code is useful for cement manufacturers and purchasers of cement in bulk quantities.
The code highlights the inspection rules and process.
The object of inspecting cement by the purchaser is to ensure its conformity to the specification requirements. The inspection done by the manufacturer during production is to ensure uniformity and reduce quality fluctuations to a minimum.
The tests to be carried out on samples includes:
- The total sulfur content as sulphuric anhydride
- Fineness test
Once the samples are taken and the cement is conformed to the standards, the next step is to carry out physical tests. These tests are to be carried out on-site to evaluate the physical properties of hydraulic cement.
3. IS 4031
The IS 4031: 1998 covers all the methods of physical tests for hydraulic cement. This standard is divided into 15 parts and each part is a helpful guide to examine one physical property. Here is the complete list:
Part 1 is about the determination of fineness - dry sieving method
Part 2 is about the determination of fineness by specific surfaces by the Blaine air permeability method
Fineness is an important property as the rate of hydration, rate of gain of strength, and rate of evolution of heat depend on it. The fineness test ensures that the procured cement is fit for the intended purpose. Part 1 and part 2 of the code.
Part 3 is about the determination of soundness
Soundness refers to the ability of the cement to retain its volume after it is hardened. Soundness can be determined by the Le-Chatelier method and the Autoclave method, both described in this section of IS 4031: 1998.
Part 4 is about the determination of the consistency of standard cement paste
The amount of water affects the setting time of cement. This test helps to identify the minimum water required to make a cement paste.
Part 5 is about the determination of initial and final setting times
These tests help find the exact amount of time for the cement to set. The initial and final standard setting time for an Ordinary Portland Cement is 30 minutes and 10 hours respectively. Determining setting time helps in two ways - one, to check the quality requirement of cement and two, to plan the concreting operation. The code lay down the standard procedure to conduct these tests.
Part 6 is about the determination of the compressive strength of hydraulic cement
Compressive strength is the key factor that governs the stability of the structure and quality of cement. Determining the compressive strength ensures the ordered cement matches the strength requirement of the structure.
Part 7 is about the determination of the compressive strength of masonry cement
Masonry cement is typically used as mortar for wall construction. Determining the strength of cement ensures that the cement maintains the load-bearing bond when loaded below the tested load results.
Part 8 is about the determination of the transverse and compressive strength of plastic mortar using a prism
This code covers the determination of the bending and compressive strength of plastic mortar.
The transverse strength ( flexural strength)of mortar is an important property to consider because the flexural strength of the mortar will determine its ability to resist bending and shear forces that may be applied to it during construction or in service. For example, if a wall is subjected to lateral loads from wind or earthquakes, the mortar between the bricks or blocks will be required to resist the resulting shear forces. Similarly, if a floor or roof slab is subjected to live loads, the mortar between the supporting beams or joists will need to have sufficient flexural strength to resist the bending moments that are generated.
The tests on the transverse strength of plastic mortar ensure that the mortar you are using will have the necessary strength to perform these functions effectively and safely.
Part 9 is about the determination of heat of hydration
These tests help predict the rate of hydration which in turn helps design the concrete mix. The heat of hydration can be used as a measure of the reactivity of cement, with higher values indicating a more reactive cement. This can be useful for quality control purposes and for selecting the most suitable cement for a given application.
Part 10 is about the determination of drying shrinkage
To ensure cement does not crack after hardening, drying shrinkage is evaluated - again a quality metric to consider.
Part 11 is about the determination of density
This part of the code covers the test for density using Le Chatelier Flask. A denser concrete provides higher strength.
Part 12 is about the determination of the air content of hydraulic cement mortar
If the air content is too high, the mortar may be too porous and weak. If it is too low, the mortar may be too dense and difficult to work with.
By knowing the air content, it is possible to predict the likely strength and durability of the mortar.
Part 13 is about the measurement of water retentivity of masonry cement
Water retentivity affects the workability, strength, and durability of cement and eventually affects its quality. By measuring the water retentivity, it is possible to ensure that the mortar will have the necessary moisture content to achieve optimal performance.
Part 14 is about the determination of false set
The occurrence of a false set can be an indication of problems with the cement, such as poor grinding or contamination. By determining a false set, it is possible to identify and address any issues with the cement and ensure that it is of high quality.
This part of the code gives guidelines to test whether the cement is setting prematurely using Vicat's apparatus.
Part 15 is about the determination of fineness - wet sieving method
By determining the fineness of the cement by wet sieving, it is possible to ensure that the cement has the desired particle size distribution for the intended application and to assess the quality of the cement.
Once all the physical tests on cement are conducted, it is time for testing chemical properties.
4. IS 4032
The methods of tests for chemical properties are described in IS 4032:1985 - Method of chemical analysis of hydraulic cement.
In this modified version of the code, rapid methods of chemical analysis of cement to cut down the time taken for the determination of major constituents are also added. The test is called the rapid complexometric (EDTA) method and is developed by National Council for Cement and Building Materials. This test has been included as an alternate method for the estimation of CaO, MgO, Fe2O3, and Al2O3 in ordinary and low-heat Portland cement, rapid-hardening Portland cement, Portland slag cement, and Portland pozzolana cement.
Along with the chemical analysis, the standard also covers tests for the determination of free lime in Portland cement, the pozzolanicity test for Portland pozzolana cement, and the staining test for masonry cement.
Why carry chemical analysis?
Chemical analysis helps determine the suitability of the cement for a specific use case. These tests help ensure that the cement conforms to the desired quality standards and is suitable to use for actual construction purposes.
This article gave you an extensive tour of IS codes on hydraulic cements. Bookmark this article for future reference. Refer to the codes mentioned to learn more about hydraulic cement and its application to enhance construction quality.
Rigorously follow the instructions shared in the IS codes.
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