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%.
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What is durability and soundness?
Durability and Soundness The soundness test determines an aggregate ‘s resistance to disintegration by weathering and, in particular, freeze-thaw cycles. Aggregates that are durable (resistant to weathering) are less likely to degrade in the field and cause premature HMA pavement distress and potentially, failure.
The soundness test repeatedly submerges an aggregate sample in a sodium sulfate or magnesium sulfate solution. This process causes salt crystals to form in the aggregate’s water permeable pores. The formation of these crystals creates internal forces that apply pressure on aggregate pores and tend to break the aggregate (Figure 1).
After a specified number of submerging and drying repetitions, the aggregate is sieved to determine the percent loss of material. Figure 1: Aggregate before (top) & after (bottom) the soundness test. The formation of salt crystals is supposed to mimic the formation of ice crystals in the field and could therefore be used as a surrogate to predict an aggregate’s freeze-thaw performance.
AASHTO T 104 and ASTM C 88: Soundness of Aggregate by Use of Sodium Sulfate or Magnesium Sulfate
What is the definition of soundness in logic?
10 Validity and Soundness A good argument is not only valid, but also sound. Soundness is defined in terms of validity, so since we have already defined validity, we can now rely on it to define soundness. A sound argument is a valid argument that has all true premises.
- That means that the conclusion of a sound argument will always be true.
- Why? Because if an argument is valid, the premises transmit truth to the conclusion on the assumption of the truth of the premises.
- But if the premises are actually true, as they are in a sound argument, then since all sound arguments are valid, we know that the conclusion of a sound argument is true.
Compare the last two Obama examples from the previous section. While the first argument was sound, the second argument was not sound, although it was valid. The relationship between soundness and validity is easy to specify: all sound arguments are valid arguments, but not all valid arguments are sound arguments.
- Although soundness is what any argument should aim for, we will not be talking much about soundness in this book.
- The reason for this is that the only difference between a valid argument and a sound argument is that a sound argument has all true premises.
- But how do we determine whether the premises of an argument are actually true? Well, there are lots of ways to do that, including using Google to look up an answer, studying the relevant subjects in school, consulting experts on the relevant topics, and so on.
But none of these activities have anything to do with logic, per se. The relevant disciplines to consult if you want to know whether a particular statement is true is almost never logic! For example, logic has nothing to say regarding whether or not protozoa are animals or whether there are predators that aren’t in the animal kingdom.
What is Type soundness?
Type systems are a ubiquitous and essential part of modern programming languages. They help to ensure that separately developed pieces of a program “fit together” properly, and they help to statically prevent programs from exhibiting a large class of runtime errors.
So what can we actually prove about a type system to ensure that it is doing its job? The most common answer is type soundness (or type safety ). Introduced originally by Robin Milner over 40 years ago, the type soundness theorem for a programming language L states that if a program P written in L passes L’s type checker, then P should be guaranteed to have well-defined behavior when executed.
Often summarized via Milner’s slogan—”well-typed programs can’t go wrong”—type soundness has become the canonical property that type systems for “safe” programming languages are expected to satisfy. However, as we will argue in this post, the most common syntactic approach to formulating type soundness omits an important aspect of why types are useful.
- In particular, as John Reynolds famously stated in 1983, “type structure is a syntactic discipline for enforcing levels of abstraction”, where “abstraction” refers to the ability of program components to hide information from other components.
- But syntactic type soundness has little to say about abstraction.
In this post, we explain how, with a semantic formulation of type soundness, we can provide a more satisfactory and comprehensive account of what type systems are good for.
What is meaning of soundness of cement cos 305 A?
Basic Civil Engineering Questions and Answers – Properties of Cement This set of Basic Civil Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Properties of Cement”.1. Why is natural cement used very limitedly? a) Brown in Colour b) Standard consistency is not met with c) Sets too quickly d) Particle size is too fine View Answer Answer: c Explanation: Natural cement sets very quickly after the addition of water and hence it is not quite workable.
Artificial cement is preferred over this.2. Who invented Portland cement and in which year? a) William Aspdin, 1824 b) William Aspdin, 1840s c) Joseph Aspdin, 1840s d) Joseph Aspdin, 1824 View Answer Answer: b Explanation: Joseph Aspdin patented Portland cement in 1824. William Aspdin, his son is regarded as the inventor of modern Portland cement due to his developments in 1840s.3.
What is the average particle size of cement? a) 15 microns b) 45 microns c) 75 microns d) 100 microns View Answer Answer: a Explanation: Approximately 95% of cement particles are smaller than 45 microns and the average particle size is 15 microns. Note: Join free Sanfoundry classes at or 4.
What is the meaning of soundness of cement? a) Ability to flow when mixed b) Ability to make ringing noise when struck c) Ability to form strong and sound structure d) Ability to retain volume after setting. View Answer Answer: d Explanation: When cement paste hardens and sets, it should not undergo any volume change.
Soundness ensures this and is tested using Autoclave expansion test.5. Time elapsed from the instance of adding water until paste ceases to behave as fluid is called: a) Initial setting time b) Final setting time c) Intermediate setting time d) Absolute setting time View Answer Answer: a Explanation: Final setting time is the time required for cement paste to reach a certain state of hardness.
- Option c and d does not exist.
- Take Now! 6.
- Which of the below mentioned is not a result of field test performed on cement? a) There should not be any lumps b) It should feel cold when you put your hand in bag of cement c) The colour should be blackish grey d) It should not be gritty when rubbed with finger View Answer Answer: c Explanation: The colour of cement is normally grey with a greenish tint.
There are different shades – lighter and darker, but it does not go as dark as blackish grey.7. Which equipment is used to test the setting time of cement? a) Core cutter b) Vibrator c) Universal testing machine (UTM) d) Vicat apparatus View Answer Answer: d Explanation: Core cutter is used to determine dry density of soil.
- Vibrator is used in sieve analysis.
- UTM can be used to test various parameters – tension, bending, shear of various materials.
- Vicat apparatus consists of a needle, used to penetrate the cement paste sample.8.
- What is the initial setting time of cement? a) 1 hour b) 30 minutes c) 15 minutes d) 30 hours View Answer Answer: b Explanation: As per IS code 4031-part 5, the initial setting time of cement is minimum of 30 minutes.
After this cement will start losing its plasticity and will not be workable.9. Use of coarser cement particles leads to: a) Low durability b) Higher strength c) Low consistency d) Higher soundness View Answer Answer: a Explanation: For coarser particles, hydration starts on the surface of particles, hence, it might not be completely hydrated.
This causes low strength and low durability.10. Wet cement can cause severe skin burns if not washed off with water immediately. a) True b) False View Answer Answer: a Explanation: Cement is highly alkaline and setting process is exothermic. Wet cement is strongly caustic and causes skin burns. Similarly, dry cement causes eye or respiratory irritation, when it comes in contact with mucous membranes.11.
Green cement is: a) Green coloured cement b) Cement mixed with plant products c) Cement mixed with recycled materials d) Cement mixed with green algae View Answer Answer: c Explanation: Green cement is a cementitious material which employs the use of optimized recycled materials.
These can meet or even exceed the functional performance of Portland cement.12. What is the depth the needle in Vicat apparatus should penetrate into the cement paste in consistency test? a) 33-35 cm from bottom of the mould b) 33-35 mm from top of the mould c) 33-35 cm from top of the mould d) 33-35 mm from bottom of the mould View Answer Answer: b Explanation: The best procedure has been clearly mentioned in IS 4031 Part 4.
According to the code, 33-35mm depth of penetration is ideal. Sanfoundry Global Education & Learning Series – Basic Civil Engineering. To practice all areas of Basic Civil Engineering,, Next Steps:
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