1. objective – It is very important that the cement after setting shall not undergo any appreciable change of volume. Certain cements have been found to undergo a large expansion after setting causing disruption of the set and hardened mass. This will cause serious difficulties for the durability of structures when such cement is used.
The unsoundness in cement is due to the presence of excess of free lime than that could be combined with acidic oxide at the kiln. It is also likely that too high a proportion of magnesium content or calcium sulphate content may cause unsoundness in cement. Soundness of cement may be determined by two methods, namely Le-Chatelier method and autoclave method.
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.
- 1 Which one is responsible for unsoundness of cement?
- 2 Which of the following compound is responsible to control the strength and soundness of cement?
- 3 What is soundness property?
- 4 How do you identify unsound concrete?
Which one is responsible for unsoundness of cement?
Free CT 1: Current Affairs (Government Policies and Schemes) 10 Questions 10 Marks 10 Mins Explanation: The unsoundness in cement is due to the presence of an excess of free lime, magnesia and sulphur trioxide. Soundness Test: Expansion of cement is measured/computed by soundness test.
Soundness means the ability to resist volume expansion and it is indication durability. The soundness of cement may be determined by two methods, namely Le-Chatelier method and autoclave method. The Le-Chatelier test detects unsoundness due to free Lime only. This method of testing does not indicate the presence and after effect of the excess of magnesia.
As per Indian Standard specification, if the content of magnesia is greater than 3% in cement then Autoclave Test is performed which is sensitive to both Lime and Magnesia. Latest DFCCIL Junior Manager Updates Last updated on Sep 29, 2022 Dedicated Freight Corridor Corporation of India (DFCCIL) will soon release the official notification for the DFCCIL Junior Manager Recruitment 2022.
What is the role of Fe2O3 in cement?
It was founded that the optimal quantity of Fe2O3 is 0,01 % by weigth of cement in the presence of polymer powder PAV-22, because it increases the hardened cement stone flexural strength, and slightly decrease the compressive strenght.
What is unsoundness of brick?
|29.||Consider the following statements : 1. About 25% of alumina is brick earth imparts the plasticity necessary for moulding bricks into required shape.2. Iron pyrite present in brick earth preserves the form of the bricks at high temperatures.3. Presence of weeds in brick earth makes the bricks unsound. Which of these statements are correct ?|
Answer: Option B Explanation: No answer description available for this question. Let us discuss,
Which of the following compound is responsible to control the strength and soundness of cement?
Silica is responsible for strength of cement, alumina imparts quick setting property, Calcium Sulphate delays setting of cement, Magnesium Oxide in large quantity-causes delayed expansion.
What is soundness property?
Logical systems – In mathematical logic, a logical system has the soundness property if every formula that can be proved in the system is logically valid with respect to the semantics of the system. In most cases, this comes down to its rules having the property of preserving truth, The converse of soundness is known as completeness, A logical system with syntactic entailment and semantic entailment is sound if for any sequence of sentences in its language, if, then In other words, a system is sound when all of its theorems are tautologies, Soundness is among the most fundamental properties of mathematical logic. The soundness property provides the initial reason for counting a logical system as desirable. The completeness property means that every validity (truth) is provable.
Together they imply that all and only validities are provable. Most proofs of soundness are trivial. For example, in an axiomatic system, proof of soundness amounts to verifying the validity of the axioms and that the rules of inference preserve validity (or the weaker property, truth). If the system allows Hilbert-style deduction, it requires only verifying the validity of the axioms and one rule of inference, namely modus ponens,
(and sometimes substitution) Soundness properties come in two main varieties: weak and strong soundness, of which the former is a restricted form of the latter.
How do you identify unsound concrete?
4.1 Finding Unsound concrete – The first step in constructing a successful partial-depth repair is the identification and removal of all deteriorated concrete. Unsound concrete is commonly located by “sounding out ” the delaminated area. Sounding is done by striking the concrete surface with a steel rod or ball-peen hammer, or by dragging a chain along the surface.
|“Sounding” with a ball-peen hammer “Sounding” with a steel chain|
Which of the following oxides composition causes unsoundness of cement?
Functions of Chemical Compounds Present in Cement – Calcium Oxide CaO It controls the strength gain of cement It controls the soundness of cement Deficiency of CaO in cement reduces strength as well as the setting time of cement. Silica SiO 2 It provides strength to cement.
- Excess of silica reduces the setting of cement.
- Aluminium Oxide Al 2 O 3 It is responsible for the quick setting of cement Excess of aluminium oxide reduces the strength of cement Ferrous Oxide Fe 2 O 3 It imparts the characteristic grey colour to the cement It also helps in the fusion of different materials Magnesium Oxide MgO It provides colour to the cement It also provides hardness to the cement Excess of magnesium oxide causes cracks in mortar and produces unsound concrete.
Alkalis Na 2 O, K 2 O, P 2 O 5 Alkalis are present as residues in cement. Excess of alkalis causes efflorescence in concrete Excess of alkalis may also result in the cracking of the concrete Sulphur Trioxide SO 3 Sulphur trioxide provides soundness to the cement.