Soundness – The soundness test determines whether hardened cement paste is prone to excessive expansion by boiling the test specimens for a fixed period of time. The soundness of cement is mainly tested by two methods: EN-196 (1995), which is based on the Le Châtelier test method, and the autoclave test (ASTM-C151, 2015), in which pressure is also applied to the sample.
The soundness values for hardened cement paste specimens produced with 2.5–6% CS ( Alp et al,, 2008 ) showed an average reduction of 13% in expansion when compared to control specimens without CS. Other studies also showed that the incorporation of CS as part of the raw feed may allow the production of cement clinker with equivalent ( Ali et al., 2013 ) or lower expansion ( Supekar, 2007 ) than that of control PC without CS.
Expansion of specimens containing 2.5% CS decreased by 20% when compared to the corresponding PC specimens. These results can be correlated with the decrease in the free CaO content ( Alp et al., 2008; Supekar, 2007 ). The reason for this is that, by applying elevated temperatures (or pressure in the autoclave test method), it is possible to measure the extent of expansion caused by the delayed hydration of unburnt CaO.
- 1 What is soundness property of cement?
- 2 What is stabilizing property?
- 3 What is the first test to be done for determining any property of cement?
- 4 Which test determines unsoundness of cement due to excess of calcium sulphate?
- 5 Which test is used to measure the durability of cement?
Which property of cement is measured by soundness test?
In the soundness test a specimen of hardened cement paste is boiled for a fixed time so that any tendency to expand is speeded up and can be detected. Soundness means the ability to resist volume expansion.
What is soundness property of cement?
3 Soundness – The soundness of cement refers to the stability of the volume change in the process of setting and hardening. If the volume change is unstable after setting and hardening, the concrete structures will crack, which can affect the quality of buildings or even cause serious accidents, known as poor dimensional stability.
The cement product whose dimensional stability is poor will be disposed as spoiled product, not used in projects. The reasons for poor dimensional stability are: the free calcium oxide ( f -CaO) in the clinker is too much, or the free magnesium oxide in the clinker ( f -MgO) is quite a little, or the gypsum mixed in the clinker is excessive.
f -CaO and f -MgO in the clinker are all sintered, so their ageing speed is very slow. They start ageing slowly after the setting and hardening. CaO + H 2 O = Ca OH 2 MgO + H 2 O = Mg OH 2 In the ageing process, there is volume expansion which causes the cracking of cement.
- The excessive amount of gypsum will react with the solid calcium aluminate hydrate to generate crystals of calcium sulfoaluminate hydrate.
- Thus, the volume will expand 1.5 times, which leads to the cracking of cement paste matrix.
- The national standards require: boiling method can be used to inspect the poor dimensional stability of the cement caused by the free CaO.
The so-called boiling method includes Pat test and Le Chatelier test. Pat test is to make the cement paste of normal consistency into cement cake, boil it for 3 h, and then observe it by naked eyes. If there is no crack and no bending by ruler inspection, it is called qualified soundness.
Le Chatelier test is to measure the expansion value after the cement paste is boiled and get hardened on Le Chatelier needles. If the expansion value is within the required value, its stability is qualified. If there is contradictory between the results measured by Pat test and Le Chatelier test, Le Chaterlier test should prevail.
The hydration of free magnesium oxide is slower than that of free calcium oxide. Therefore, its harm can be inspected only by autoclave test. The harm of gypsum will be found by immersing in room-temperature water for a long time. Then the poor dimensional stability caused by magnesium dioxide and gypsum is inconvenient to be tested rapidly.
Thus, they should be controlled strictly in the production of cement. The national standards require: the content of free magnesium oxide in cement should not be more than 5.0%, and the content of sulfur trioxide in slag cement should not be more than 4.0% and that in other kinds of cement should not exceed 3.5%.
Read full chapter URL: https://www.sciencedirect.com/science/article/pii/B9781845699550500049
What is the purpose of soundness test?
Soundness test is performed to determine a durability of cement.
What is stabilizing property?
Property stabilization or stabilized occupancy is a projected range of occupancy for rental property. In other words, this is the expected occupancy that the project will have after being on the open market for a certain time period.
What is a stressed property?
What Is A Distressed Property? A distressed property is a home on the brink of foreclosure or already owned by the bank. Investors often seek these properties out because of the opportunity to buy a home at a discount. However, buyers are taking a risk that the property might need significant repairs.
Why tests are used to determine the properties of concrete?
🕑 Reading time: 1 minute Quality tests on concrete are performed as a part of quality control of concrete structures. Different quality tests on concrete such as compressive strength tests, slump tests, permeability tests etc.are used to assure the quality of the concrete that is supplied for a given specification.
What is the first test to be done for determining any property of cement?
Highway Engineering Questions and Answers – Portland Cement and Cement Concrete This set of Highway Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Portland Cement and Cement Concrete”.1. What is the minimum grade of concrete in CC pavement? a) M20 b) M30 c) M40 d) M50 View Answer Answer: c Explanation: The minimum grade of concrete required for pavement is M40, as it should withstand temperature and wheel stresses.
2. The cement used in water logged areas is _ a) Portland cement b) Hydrophobic cement c) Quick setting cement d) Reediest cement View Answer
Answer: b Explanation: The cement mostly used in water logged areas is hydrophobic cement as it will resist the water from clogging.3. The waste material mostly used in pavement is _ a) Fly ash b) GGBS c) Rice husk d) Soil View Answer Answer: a Explanation: The waste material mostly used in pavement is fly ash which is mostly obtained from thermal power plants.
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- The cement on touching should give _ a) Cool feeling b) Hot feeling c) neutral d) Very cool feeling View Answer Answer: a Explanation: The cement on touching with hand should give a cool feeling and not break; it should be free from lumps.5.
- Cement specific gravity is measured by _ a) Water b) Kerosene c) Oil d) Petrol View Answer Answer: b Explanation: The specific gravity of cement is measured by kerosene, because if it is measured with water then it forms heat of hydration.6.
The specific gravity of cement is _ a) 2.5 b) 1.44 c) 3.15 d) 30 View Answer Answer: d Explanation: The specific gravity of cement is 3.15, it is not like the density which is 1440 kg/m 3 because here kerosene is used for density test and in 1 metre cube of volume 30 bags may be filled.7.
One meter cube of cement consists of how many bags of cement? a) 30 b) 50 c) 15 d) 10 View Answer Answer: a Explanation: One meter cube of volume contains 30 bags of cement or 1500kg of cement, it is actually an assumption that one kg of bag consists of 50 kg cement, but density is 1440kg/m3, so approximately value is 30, but the actual value is more.8.
The density of cement in Kg/m 3 is _ a) 1440 b) 1240 c) 1340 d) 1540 View Answer Answer: a Explanation: The density of cement in Kg/m 3 is 1440; it is not 3150 because its specific gravity is measured with kerosene.9. The initial setting time of cement is not less than _ a) 30 seconds b) 300 seconds c) 30 minutes d) 300 minutes View Answer Answer: c Explanation: The initial setting time of cement is not less than 30 minutes for ordinary Portland cement and it may vary for various grades of cement.10.
What is the first test to be done for determining any property of cement? a) Consistency b) Setting time c) Soundness d) Fineness View Answer Answer: a Explanation: The first test to be done for determining any property of cement is a consistency test which lies between 27 and 29.11. The volume of water in setting time test is? a) 0.78p b) 0.75p c) 0.85p d) 0.95p View Answer Answer: c Explanation: The volume of water in the setting time test is 0.85p where p is the consistency of the cement sample.12.
The volume of water in soundness test is? a) 0.6p b) 0.7p c) 0.78p d) 0.8p View Answer Answer: c Explanation: The volume of water in soundness test is 0.78p, where p is the consistency of the cement sample.13. The property of cement by which it doesn’t expand is called _ a) Fineness b) Soundness c) Setting time d) Consistency View Answer Answer: b Explanation: The property of cement by which it doesn’t expand on contact with water is called as soundness.14.
What is the most commonly used grade of cement? a) 33 b) 43 c) 53 d) 63 View Answer Answer: c Explanation: The most commonly used grade of cement is OPC 53 grade cement for most of the purposes, fly ash is also mixed in some cement.15. What is the total grades of cement specified by IRC? a) 3 b) 6 c) 9 d) 12 View Answer Answer: c Explanation: IS has classified the grades of cement depending upon the requirement into 9 categories of various classes and materials.
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Which test determines unsoundness of cement due to excess of calcium sulphate?
The soundness of cement is determined either by Le-chatelier’s method or by means of an Autoclave test.
What are factors affecting soundness of cement?
01. Excess Lime – Soundness of cement is affected by the presence of excess lime (CaO) in the cement. This excess lime hydrates very slowly and forms slaked lime that occupies a larger volume than the original free calcium oxide. The slow hydration process, therefore, affects the properties of hardened concrete.
How do you determine the fineness of cement?
Fineness of cement is tested in two ways : (a) By sieving. (b) By determination of specific surface (total surface area of all the particles in one gram of cement) by air-permeability apparatus. Expressed as cm2/gm or m2/kg. Generally Blaine Air permeability apparatus is used.
What is the purpose of soundness test?
Soundness test is performed to determine a durability of cement.
Why is it important to test soundness cement?
Significance of Soundness Test on Cement – Cement is a composition of lime, silica, alumina, magnesia, alkaline, sulfur trioxide, iron oxide, and calcium sulfate. Among which, lime constitutes 60 to 70%. Hence, a cement deficient in lime will set quickly and will affect the property of the cement.
Which test is used to measure the durability of cement?
Concrete durability testing – Kryton International Inc. To have a sustainable concrete structure, durability is key. Use of inappropriate materials, poor construction practices, curing and mix designs, results in concrete structures often showing serious premature deterioration.
This is a global problem that annually costs public and private sectors worldwide billions of dollars. Measuring the durability of concrete to determine its longevity in service is challenging. It is, however, important in identifying how sustainable structures will ultimately be. Tests such as water absorption, surface absorption, water permeability, or chloride permeability are commonly specified.These tests should consider the unique properties of the mix design when used to determine concrete’s durability.
They also have some limitations and it is necessary to understand and recognise them. Measuring the durability factor of concrete to determine its longevity is difficult to predetermine. It is, however, an important factor in identifying how sustainable the structure will be. Absorption Tests Description : Absorption testing is a common method of determining water resistance.
Tests such as BS 1881-122:2011 measure the amount of water that penetrates into concrete samples when submersed. Low absorption is a positive result. Where it’s most useful : The test is intended to determine the susceptibility of unsaturated concrete to water penetration, for both surface and interior concrete.
- Short submersion time compared to long-term service conditions
- Does not account for any reactive process that binds water
- Assumes all weight gain is water and not reactive processes
- Can be misleading when using admixtures such as hydrophilic crystalline waterproofing admixtures. Absorption testing
- measures the amount of water penetrating into concrete samples when submersed, but fails to consider the inherent use of water in the crystallization process, particularly in the early stages of curing (less than 28 days).
The absorption test results will improve over time as the crystals continue to grow. Therefore, for crystalline admixtures, testing the absorption at later ages (56 or 90 days) will give more realistic results. The durability of a concrete mix design is always dependent on the environmental factors of the structure it will be supporting. Rapid Chloride Permeability test Description : The Rapid Chloride Permeability (RCP) test is an electrical test used to estimate the durability of concrete.
Test methods – like ASTM 1202, Standard Test Method for Electrical Indication of Concrete’s Ability to Resist Chloride Ion Penetration – monitor the amount of electrical charge passed through cylindrical specimens for six hours. The total charge passed, in coulombs, is related to the specimen’s ability to resist chloride ion penetration.
Lower levels of charge passed indicate higher resistance. Where it’s most useful : The RCP test has gained wide acceptance as a relatively easy and quick method for determining concrete permeability. Overall, this test method is suitable for evaluating materials and material proportions for design purposes, and for research and development.
- However, it has incorrectly become one of the tests used to evaluate concrete durability.
- RCP can qualify a mix, but not necessarily disqualify it.
- The RCP test should not be used to accurately determine the permeability of concrete mixes containing supplementary cementitious materials or chemical admixtures.
Limitations : Various drawbacks make the test unreliable, especially for comparing different mix designs or for evaluating concrete durability.
- It may allow for premature measurements (before a steady state is achieved);
- The high voltage applied increases temperature in the sample, and can cause physical and chemical changes, and unrealistic values;
- Electric current passing through the sample indicates the movement of not just chloride ions, but all ions in the pore solution (the sample’s electrical conductivity); this test may thus not represent true (or potential) permeability of concrete containing supplementary cementitious materials (fly ash, silica fume, or ground granulated blast-furnace slag) or chemical admixtures (water reducers, superplasticisers, corrosion inhibitors);
- Possible misleading results due to the chemical composition of the pore solution, rather than the true permeability;
- Low repeatability and reproducibility.
Water Permeability test Description : BS EN 12390-8 and DIN 1048 Part 5 are equivalent tests measuring depth of water penetration into concrete samples subjected to 0.5 MPa of hydrostatic pressure over three days.
- Concrete specimens are cast and cured for 28 days and then placed in the testing device.
- The sample holders are open at both ends, with one end subjected to hydrostatic pressure.
- After three days, the samples are removed from the testing apparatus, cracked in half vertically and maximum depth of water penetration measured.
- Where it’s most useful : This test determines the true permeability of concrete by evaluating concrete’s resistance to penetration of water under hydrostatic pressure and should be the preferred test if concrete is subjected to hydrostatic pressure.
The smaller the depth of penetration, the greater the resistance to water under hydrostatic pressure. This test is useful for basements, tunnels, and water reservoirs, since it realistically recreates pressure conditions to which these structures are subjected. Limitations:
- For dense and low-permeability mixes, the depth of water penetration is low, making it difficult to compare mixes that have low permeation (in these cases the pressure or testing age can be modified); and
- For concrete not under hydrostatic pressure, this test should be used in conjunction with absorption testing.
- Environmentally specific mix designs are necessary for every unique condition, as are service-environment-appropriate testmethods.
- Absorption tests are best suited to concretes with little or no hydrostatic pressure and permeability tests should be the main test to evaluate concrete subjected to hydrostatic pressure.
- The focus of specifications for testing concrete durability should be on determining the concrete’s permeability, resistance to environmental factors, and tendency to crack.
Alireza Biparva, B.Sc., M.A.Sc. KrytonResearch and Development Manager
- Source: Concrete Trends
: Concrete durability testing – Kryton International Inc.