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Komal Bhandakkar
Komal Bhandakkar

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How to check the purity of cement?

  1. nikeetasharma

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    The purity of cement can be checked by following ways :- 1. RUBBING :- Take a small quantity of cement between your fingers and rub it. It must feel smooth while rubbing but if it feels rough than adulteration with sand. 2. HAND INSERTION :- Insert your hand into the cement bag and it should give coRead more

    The purity of cement can be checked by following ways :-
    1. RUBBING :- Take a small quantity of cement between your fingers and rub it. It must feel smooth while rubbing but if it feels rough than adulteration with sand.

    2. HAND INSERTION :- Insert your hand into the cement bag and it should give cool feeling. Hence this cool feeling indicates that there is no hydration reaction is taking place in the bag.

    3. FLOAT TEST :- It is tested by throwing a small quantity of cement in a bucket of water. Thus it should sink and should not float on the surface.

    4. SMELL TASTE :- Take some quantity of cement and smell it. If the cement contains too much of pounded clay and silt as an adulterant, the paste will give an earthy smell.

    5. PRESENCE OF LUMPS :- See that the lumps should not be present in the bag while opening the bag. Thus it ensures that no setting has taken place.

    6. COLOUR :- Basically, the cement should be uniform in colour. Generally the colour of cement is grey with a light greenish shade. The colour of cement gives an indication of excess lime or clay and the degree of burning.

    7. DATE OF PACKING :- Date of manufacturing should be seen on the bag. It is most important because the strength of cement reduces with age.

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Leon
Leon

Leon

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I purchased a home and with all the recent rain I removed the basement paneling to find a leak. I discovered the home at one time had no garage. T some time the window well (see attachment) had been covered ...

  1. AdityaBhandakkar

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    Below grade window fill

    Hi, Recently I go through the image you attached, yes it possible to repair the leakages and seal with concrete with some admixtures. I suggest you contact with the locally available contractor for repairs. But if you are a civil engineer, the following are some suggestions. Following are some repaiRead more

    Hi,

    Recently I go through the image you attached, yes it possible to repair the leakages and seal with concrete with some admixtures. I suggest you contact with the locally available contractor for repairs. But if you are a civil engineer, the following are some suggestions.

    Following are some repairing methods for leakages

    1. Resin injection: used for repairing the concrete saw delaminated and also used for joints that experience water leakage. Metals are used for rebound cracks, whereas polyurethanes and acrylic acrylates are used to seal the cracks and joints that leak water.
    2. Stitching cracks: it is a long-lasting and easiest method where the holes are drilled, and the surface is stitched with the help of a metallic wire. Is metallic wires are passed through the holes and anchored strongly, and the vacant spaces are grouted.
    3. Gravity field method: in this method instrument with waterproofing admixture used to fill the cracks with the help of the gravity where it is allowed to move inside the cracks by gravity forces and sealed it. It is used for the cracks with width 0.03mm to 20mm cracks
    4. Micro toppings: Polymer with 1/8 inches, which contained a modified concrete and sand, are applied with the help of trowels. This treated surfaces can be allowed for public use within 36 to 42 hours of usages.
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Gopal Mishra
Gopal Mishra

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Cement volume is 0.25m3, Sand volume is 0.25m3, Coarse aggregate volume is 0.5m3. Concrete grade is M25.(mix proportion is 1:1:2). What will be the concrete volume in m3?

  1. Gopal Mishra

    Gopal Mishra

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    Gopal Mishra

    Volume of fully compacted concrete is given by following formula: where Vc is the volume of concrete. W, C, Fa and Ca are the masses of water, cement, fine aggregates and coarse aggregates respectively. Density of cement = 1500 kg/m3, fine aggregates = 1700 kg/m3 and coarse aggregates = 1650 kg/m3.Read more

    Volume of fully compacted concrete is given by following formula:

    volume of concrete formula

    where Vc is the volume of concrete. W, C, Fa and Ca are the masses of water, cement, fine aggregates and coarse aggregates respectively.

    Density of cement = 1500 kg/m3, fine aggregates = 1700 kg/m3 and coarse aggregates = 1650 kg/m3. 

    So, Weight of cement C = 0.25 x 1500 = 375kg

    Weight of Fine aggregates Fa = 0.25 x 1700 = 425 kg

    Weight of Coarse aggregates Ca = 0.5 x 1650 = 825 kg

    Consider w/c ratio as 0.45, so weight of water = 0.45×0.25×1000 = 112.5 L or kg

    Sc, Sfa and Sca are the specific weight of cement, fine aggregates and coarse aggregates which are 3.15 for cement and 2.6 for fine and coarse aggregates.

    Therefore, putting these values in the formula above, we get

    Vc = (112.5/1000)+(375/(1000×3.15))+(425/(1000×2.6))+(825/(1000×2.6)) = 0.712m3

    So, Volume of concrete = 0.712m3

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Ertanishpachnanda
Ertanishpachnanda

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How can we reduce laitance from concrete structures?

  1. nikeetasharma

    nikeetasharma

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    Laitance can be reduced by controlling the amount of water in the concrete mix during construction. If too much water remains in the concrete than various other issues can be found like greater shrinkage with the possibility of more cracks and reduced compressive strength overall.

    Laitance can be reduced by controlling the amount of water in the concrete mix during construction. If too much water remains in the concrete than various other issues can be found like greater shrinkage with the possibility of more cracks and reduced compressive strength overall.

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vivek gami
vivek gami

vivek gami

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What is Cement Gel in Concrete?

  1. nikeetasharma

    nikeetasharma

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    The cement gel in a cement is generally known as calcium silicate hydrate (CSH). It helps in strength and binding property. The production of cement gel occurs when a hydration reaction occurs by mixing water and cement; the paste so formed is called as cement gel.

    The cement gel in a cement is generally known as calcium silicate hydrate (CSH). It helps in strength and binding property. The production of cement gel occurs when a hydration reaction occurs by mixing water and cement; the paste so formed is called as cement gel.

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Komal Bhandakkar
Komal Bhandakkar

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Which equipment used to measure sound passing through the concrete?

  1. nikeetasharma

    nikeetasharma

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    dB meter

    dB meter

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Sonali Arora
Sonali Arora

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What is Concrete cancer  and what is the cause of this defect? How can concrete cancer be avoided?

  1. RaghavArora

    RaghavArora

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    CONCRETE CANCER - The phenomena in which extensive expansion of concrete occurs and may lead to the total disruption and disintegration of concrete is called concrete cancer. This process is popularly known as Alkali - Aggregate Reaction. CAUSE - This phenomenon occurs due to the reaction between AlRead more

    CONCRETE CANCER – The phenomena in which extensive expansion of concrete occurs and may lead to the total disruption and disintegration of concrete is called concrete cancer. This process is popularly known as Alkali – Aggregate Reaction.

    CAUSE – This phenomenon occurs due to the reaction between Alkalis in cement and silica in aggregate. This reaction results in extensive pop-outs and cracking in a fairly closed pattern of concrete, a year or more after the concrete has been cast, and further leads to concrete cancer.

    PREVENTION –

    • BY SELECTING NON REACTIVE AGGREGATE – Non – reactive aggregates can be identified by chemical test, mortar bar test and petrographic examination.

     

    • BY USING LOW ALKALI CEMENT – CEMENT WITH ALKALI LESS THAN 0.6% SHOULD BE USED.

     

    • BY AIR ENTRAINING AGENTS – The alkali – silica gel imparts osmotic pressure over the set concrete and further this osmotic pressure is main cause of cracks. but when air entraining agents are added, they absorb osmotic pressure and, resultantly, control the expansion.

     

    • BY CONTROLLING MOISTURE – the old concrete should not be allowed top come in water contact. Apply mortar amalgamated with water proofing agents to control the moisture in concrete.

     

    • BY ADDING PUZZOLANAS – the cause of reaction is particular proportion and fineness of silica but when fly ash or surkhi is added, the particular proportion and fineness of silica is disturbed and aggregates do not react.

     

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dhiraj010kumar
dhiraj010kumar

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While preparing a Design Mix for any Grade, if we have aggregated in two sizes like 10 mm & 20 mm or In fact Sometimes, we do use to have 40 mm aggregate as well. Is there Any IS Code Provision ...

  1. dbnalawade

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    Following points part of the answer to the question : IS 456  and IS 1343 are the code of practice you can use. The method of proportions aggregates for concrete is part design mix process. Size and Grading impacts the design mix greatly. larger the size of aggregate smaller is the cement requiremenRead more

    Following points part of the answer to the question :

    • IS 456  and IS 1343 are the code of practice you can use.
    • The method of proportions aggregates for concrete is part design mix process.
    • Size and Grading impacts the design mix greatly.
    • larger the size of aggregate smaller is the cement requirement for a given W/C ratio
    • Compressive strength of the mix tends to increase with decrease in aggregate size.
    • perform gradation tests using sieves. Coarse aggregates should conform to table 2 of IS 383 and Fine aggregate should conform to Zone 1 of IS 383

    There is ACI method available for the same exercise ACI 211.1is the code you can use.

     

    Hope this helps.

     

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