IS 2185 PDF
Bhartṛhari—Nītiśatakam. “Knowledge is such a treasure which cannot be stolen” . IS (): Concrete masonry units, Part 1: Hollow and solid concrete. “Knowledge is such a treasure which cannot be stolen”. IS (): concrete masonry units, Part 3: Autoclaved cellular Aerated concrete blocks [CED IS Concrete masonry units, Part 1: Hollow and solid concrete blocks. by Bureau Designator of Legally Binding Document: IS
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This Product Manual shall be used as reference material by all Regional/Branch Offices & licensees to ensure coherence of practice and transparency in. “Knowledge is such a treasure which cannot be stolen”. IS (): Concrete masonry units, Part 4: Preformed foam cellular concrete blocks [CED 53 . Bhartṛhari—Nītiśatakam. “Knowledge is such a treasure which cannot be stolen” . IS (): concrete masonry units, Part 2: Hollow and solid light weight.
A comparison of different curing methods and its effect on strength has been reported which suggest autoclaving or humid air curing method. Durability properties like permeability, sorptivity and other properties like thermal properties, acoustical properties and fire resistance are also dealt with.
Safwan A Khedr et al studied the durability properties of aerated concrete. Concrete mixtures with different cement contents, air content ranges and water content were subjected to abrasion test, and were exposed to sulphuric acid, calcium chloride and ammonium sulphate. Aerated concrete shows better resistance to chemical attack in terms of reduced mass loss and or higher number of exposure cycle and less permeability but the abrasion resistance is slightly low.
IS (Part 1)
E K Kuhanandan Nambiar and K Ramamurthy studied the shrinkage behavior of prefoamed concrete and the influencing factors such as density, moisture content and composition which includes filler — cement ratio, foam volume etc.
Since coarse aggregates are absent in aerated concrete, shrinkage of foam concrete is lower than normal concrete. Shrinkage increases greatly in the range of low moisture content.
Even though removal of water from comparatively bigger artificial air pores will not contribute to shrinkage, artificial air voids may have, to some extent, an effect on volume http: Elson John stability indirectly by allowing some shrinkage; this effect was more at a higher foam volume. Shrinkage decreases with an increase in foam content.
E Muthukumar and K Ramamurthy studied the influence of fineness of aluminium powder through an evaluation of variation in the workability of the mix, rate of aeration and fresh density with time, dry density, compressive strength and water absorption of aerated cement paste and mortar. The dosage of aluminium powder required to achieve a desired density reduces with an increase in its fineness.
For a given dry density or compressive strength of aerated cement paste or mortar, the water absorption increases with fineness of aluminium powder. For a given fineness of aluminium powder, appropriate dosage and water cement ratio required has to be identified based on the desired density and strength, or strength to density ratio.
The paste- void interface in aerated concrete investigated in relation to the paste aggregate interface in normal concrete revealed the existence of an interfacial transition zone. Fly ash acts as nucleation mechanism for hydration of cement paste. In the transition zone air voids acts as aggregates of zero density. K Ramamurthy and N Narayanan studied the influence of composition and curing on the drying shrinkage of aerated concrete.
Drying shrinkage is significant in aerated concrete due to high porosity and specific surface of pores, but the affecting factors are different for the aerated concrete compared to normal concrete due to the absence of coarse aggregates.
IS Concrete masonry units, Part 1: Hollow and solid concrete blocks
This paper contains experiments conducted to ascertain the influence of composition on autoclaved and non-autoclaved. The result shows that the increase in lime cement ratio and fly ash content increases the drying shrinkage.
Significant reduction in drying shrinkage is observed in autoclaved aerated concrete which means, the drying shrinkage is a function of physical structure of hydration products. The spread test was conducted for each mix for the assessment of the fluidity Figure 1.
Mortar cubes of 50cm2are cast to determine the compressive strength at 7 and 28 days of water curing. Specimen Preparation -Mortar cubes are cast in-order to study the compressive strength of mortar with Aluminum powder. Three specimens each for 7 and 28 days are prepared. The moulds were partially filled in the fresh state and the excess material bulged out were removed with the help of a sharp knife Figure 1.
Dosages of Aluminium powder used are 0. A cement to sand ratio of 1: The percentage of super plasticizer is fixed as 0. The water cement ratio adopted is 0. The water cement ratio is kept constant for all the mixes as it has direct link with the density of the aerated light weight concrete. Figure 1 Final stage after hydration of aerated concrete occurred 4.
At the end of one minute, the Aluminium powder is added into the dry mix because it tends to float on the mixing water. The ingredients are mixed until the Aluminium powder is thoroughly distributed in the mix. Then the water and the superplastizer were added together in the dry mix. The superplasticizer were mixed in the water as it is observed earlier that it improves the efficiency of the superplasticizer. After adding the water the mix were again mixed for two more minutes.
Excessive mixing time can lead to the start of reaction of Aluminium with water and starts producing air.
Therefore, it is advisable to pour the aerated concrete mix into the mould before the reaction starts. Then the Flyash content is kept constant and Aluminum powder is varied. Tests are performed under standard laboratory conditions and compressive strength were determined at 7 and 28 days of water curing.
The results are shown in Table 2 and the Figure 2 shows the respective variations at optimum percentages of Aluminum powder. Concrete masonry constructron is also economical because of the following aspects:. It lends itself to a wide variety of surface finishes for both exterior and interior walls.
It may also be finished with cement plaster, gauged withlime or a plasticizer. Concrete masonry units provide a strong mechanical key, uniting the concrete masonry backing and the plaster finish in a strong permanent bond. The hollow load-bearing concrete block of the standard X x mm size will weigh between 17 and 26 kg when made with normal weight aggregate.
Normal weight units are made with such aggregates as sand, gravel, crushed stones and air-cooled slag. Further- more, to avoid confusion with slabs and panels, the height of the block shall not exceed either its length or six times its width.
These are connected together by webs. Actual dimensions shall be 10 mm short of the nominal dimensions or 6 mm short in special cases where finer jointing is specified. The nominal dimensions of the units are so designed that taking account of the thickness of mortar joints, they will produce wall lengths and heights which will conform to the principles of modular CO- ordination.
In the case of special concrete masonry unit,s such as jallie or screen wall block and ornamental block, the specified sizes may not necessarily apply.
Depending upon the core moulds used, the face shells and webs shall be flared and tapered or straight tapered, the former providing a wider surface for mortar. The thickness of the face shell and web shall be not less than the values given in Table 1, as appropriate. The bedding surfaces shall be at right angles to the faces of the blocks.
However, it shall be ensured that blending of fly ash with cement is as intimate as possible, to achieve maximum uniformity. Part I For use as pozzolana. SSpecification for coarse and fine aggregates from natural sources for concrete. Additives or admixtures used in the manufacture of concrete masonry units may be:.
Where no Indian Standards apply, the additives qr admixtures shall be shown,by test or experience, to be not detrimental to the durability of the concrete. The consistency of the mix should be such that it may cohere when compressed in the hand without free water being visible. Too little water causes the mix to be friable, while too much water causes difficulty in the immediate withdrawal of the mould.
Part III For use as fine aggregate for mortar and conctere. SSpecification for admixtures for concrete. Part II For use as admixture for concrete. In addition to the grading of the aggregate and the quantity of cement, the amount of water required f8r mix will depend to an extent on the type of machine on which blocks are produced.
It is possible to judge the proper consistency by squeezing a handful of concrete mixture. Ten percent extra cement may be added when hand-mixing is resorted to.
When the blocks are cured in an immersion tank, the water of the tank shall be changed at least every 4 days. NOTE - The curing yard is a paved yard subdivided by shallow drains in 4 to 5 m square platforms which are provided with water fountains in the centre. The blocks are stacked on the platforms around the fountains, which work continuously. The fountains are connected to an elevated water storage tank.
They shall be stacked with voids horizontal to facilitate through passage of air. The blocks shall be allowed to complete their initial shrinkage before they are laid in a wall.
Textures may also be developed by treating the face of the units while still green by wire brushing or combing, by slightly eroding the surface by playing a fine spray of water upon it, and by splitting split block. Colour may be introduced by incorporating non- fading mineral pigments in the facing concrete, or by applying a coloured cement grout or paint to the face of the units soon after they are removed from the moulds. Selected coloured aggregates may also be used in the facing and exposed by washing with water or dilute hydrochloric acid.
If, however, it is intended to plaster concrete masonry, the block shall have a sufficiently rough surface to afford a good key to the plaster.
Waterproofing admixtures may be used for preparing the plaster. Minor chipping resulting from the customary methods of handling during delivery, shall not be deemed grounds for rcjcction. From these samples, the blocks shall be taken at random for conducting the tests.
When this is not practicable, the sample shall be taken from the stack in which case the required number of blocks shall be taken at random from across the top of the stacks, the sides accessible and from the interior of the stacks by opening trenches from the top. The blocks shall be kept under cover and protected from extreme conditions of temperature, relative humidity and wind until they are required for test.
The tests shall be undertaken as soon as practicable after the sample has been taken. A11 the 20 blocks shall be checked for dimensions and inspected for visual defects See 8. The remaining 3 blocks shall be reserved for retest for drying shrinkage and moisture movement if a need arises.
If one or more specimens fail to satisfy the requirements, the remaining 3 blocks shall be subjected to these tests.
All these blocks shall satisfy the requirements. The Standard Mark on products covered by an Indian Standard conveys the assurance that they have been produced to comply with the requirements of that standard under a well defined system of inspection, testing and quality control which is devised and supervised by BlS and operated by the producer.
Standard marked products are also continuously checked by BIS for conformity to that standard as a further safeguard.
IS (): concrete masonry units, Part 3:
Details of conditions under which a Iicence for the use of the Standard Mark may be granted to manufacturers or producers may be-obtained frdm the Bureau of Indian Standards. Cored units shall also be measured for minimum thickness of face shells and webs. Face-shell thickness and web thick- ness shall be measured at the ; hinnest point of each such element 15 mm. Where opposite face shells differ in thickness by less than 3 mm, their measurements shall be averaged. Sash grooves, dummy joints, and similar details shall be disregarded in the measurements.
After cooling the blocks to room temperature, the dimensions of each block shall be measured in centimetres to the nearest millimetre and the overall volume computed in cubic centi- metres. The blocks shall then be weighed in kilograms to the nearest 10 g and the density of each block calculated as follows:. When the bearing area of the steel blocks is not sufficient to cover the bearing area of the masonry specimen, steel bearing plates meeting the requirements of C-l.
NOTE - It is desirable that the bearing faces of blocks and lates used for com- pression testing of concrete masonry have a hardness of not less t L n 60 HRC. The centre of the sphere of the spherically Peated upper bearing block shall coincide with the centre of its bearing face. If a bearing plate is used, the centre of the sphere of the spherically seated bearing block shall lie on a line passing vertically through the centroid of the specimen bearing face.
The spherically seated block shall be held closely in its seat, but shall be free to turn in any direction. The diameter of the face of the bearing blocks shall be at least 15 cm.
When steel plates are employed between the steel bearing blocks and the masonry specimen see C In no case shall the plate thickness be less than 12 mm. The strength of the full-size units shall be considered as ,that which is calculated from the average measured strength of the segments.
The age shall be reckoned from the time of the addition of water to the dry ingredients. The sulphur mixture shall be heated in a thermostatically controlled heating pot to a temperature suficient to maintain fluidity for a reasonable period of time after contact with.
Care shall be exercised to prevent overheating, and the liquid shall be stirred in the pot just before use. Four 25 mm square steel bars shall be placed on the surface plate to form a rectacgular mould approximately I2 mm greater in either inside dimension than the masonry unit.
The surface of the unit to be capped shall quickly be brought into contact with the liquid, and the specimen, held so that its axis is at right angles to the surface of the capping liquid, shall be inserted.
The unit shall be allowed to remain undisturbed until solidification is com- plete. The caps shall be allowed to cool for a minimum of 2 hodrs before the specimens arc tested.
Patching of caps shall not be permitted.
Imperfect caps shall he removed and replaced with new ones.You just clipped your first slide! This gauge shall be rigidly mounted in a measuring frame and have a recessed end which may be located upon a 5-mm diameter ball or other reference point cemented on the specimen.
Four 25 mm square steel bars shall be placed on the surfaceplate to form a rectangular mould approximately 12 mm greater ineither inside dimension than the masonry unit. The capping surface shall be planewithin 0.
It is possible to judge the proper consistency by squeezing a handful of concrete mixture. The moulds were partially filled in the fresh state and the excess material bulged out were removed with the help of a sharp knife Figure 1.
The three new specimens, in that event, shall be dried to constant length at 50 f 1C measured after cooling and the moisture movement test-carried out as described in F Suitable dishes or trays containing this solution shall beprovided to give an exposed area of solution not less than 10 cm2for each litre of volume of the oven.
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