Environment Is 1343 Code Book


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IS - code book for structural engineers. Download IS: – IS Code Book (Indian Standards) – We have compiled a Best & Standard Reference Books on Civil Engineering (Indian Standards). (PREVIEW) IS Indian Standard PRESTRESSED CONCRETE — CODE OF PRACTICE SECTION 1 GENERAL 2 REFERENCES.

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IS Hkkjrh; ekud. iwoZizcfyr daØhV— jhfr lafgrk. (nwljk iqujh{k.k). Indian Standard. PRESTRESSED CONCRETE — CODE OF PRACTICE. ( Second. IS: - (Reaffirmed ). Edition (). Price Group Indian Standard. CODE OF PRACTICE FOR. PRESTRESSED CONCRETE. CODE OF PRACTICE FOR PRESTRESSED CONCRETE. First Revision. BUREAU OF INDIAN STANDARDS. IS: - CODE BOOK -.

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Bakshi Book Free Download April Chin Book Free Download December November 3. Never Miss. Sponsored By. Sharing is Caring. About Welcome to EasyEngineering, One of the trusted educational blog. Get New Updates Email Alerts Enter your email address to subscribe to this blog and receive notifications of new posts by email. Search Your Files. Join with us. Content is protected!! When concrete lower than grade M 50 is used under these conditions, the mean total air content by volume of the fresh concrete at the time of delivery into the construction should be: For the very high sulphate concentrations in Class 5 conditions, some form of lining such as polyethylene or polychloroprene sheet; or surface coating based on asphalt, chlorinated rubber, epoxy, or polyurethane materials should also be used to prevent access by the sulphate solution.

Appropriate value for minimum cement content and the maximum free water-cement ratio are given in Table 4 for different exposure conditions. The minimum cement content and maximum water-cement ratio apply to 20 mm nominal maximum size aggregate. For other sizes of aggregate they should be changed as given in Table 5. The higher the chloride content, or if subsequently exposed to warm moist conditions, the greater the risk of corrosion.

All constituents may contain chlorides and concrete may be contaminated by chlorides from the external environment. To minimize the chances of deterioration of concrete from harmful chemical salts, the levels of such harmful salts in concrete coming from concrete materials, that is, cement, aggregates, water and admixtures, as well as by diffusion from the environment should be limited.

The total amount of acid soluble chloride content as Cl in the concrete at the time of placing shall be not more than 0. The total acid soluble chloride content should be calculated from the mix proportions and the measured chloride contents of each of the constituents.

Wherever possible, the total chloride content of the concrete should be determined. Environment Exposure Conditions 1 2 3 i Mild Concrete surfaces protected against weather or aggressive conditions, except those situated in coastal areas. Concrete exposed to condensation and rain. Concrete continuously under water. Concrete surfaces sheltered from saturated salt air in coastal area. Concrete completely immersed in sea water. Concrete exposed to coastal environment.


Suitable adjustment may be made in the minimum cement content specified in case of use of aggregate other than 20 mm nominal maximum size. For SO3 contents near the upper limit of any class, cement contents above these minimum are advised. To prevent this, the total water-soluble sulphate content of the concrete mix, expressed as SO3 should not exceed 4 percent by mass of the cement in the mix.

The sulphate content should be calculated as the total from the various constituents of the mix. Damage to concrete from this reaction will normally only occur when all the following are present together: When the materials are unfamiliar, precautions should take one or more of the following forms: Further advantage can be obtained by use of fly ash conforming to IS Part 1 or granulated blast furnace slag conforming IS as part replacement of ordinary Portland cement having total alkali content as Na2O equivalent not more than 0.

For more guidance specialist literatures may be referred. The rate of deterioration decreases as the concrete is made stronger and more impermeable, and increases as the salt content of the water increases. Where structures are only partially immersed or are in contact with aggressive soils or waters on one side only, evaporation may cause serious concentrations of salts with subsequent deterioration, even where the original salt content of the soil or water is not high.

NOTE — Guidance regarding requirements for concrete exposed to sulphate attack is given in 8. Additional protection may be obtained by the use of impermeable barriers. The additions such as fly ash or ground granulated blast furnace slag may be taken into account in the concrete composition with respect to the cement content and water-cement ratio if the suitability is established and as long as the maximum amounts taken into account do not exceed the limit of pozzolana and slag specified in IS Part 1 and IS respectively.

Full compaction is particularly important in the vicinity of construction and movement joints and of embedded water bars and reinforcement.

Good finishing practices are essential for durable concrete.

IS 1343: Code of Practice for Prestressed Concrete

It is essential to use proper and adequate curing techniques to reduce the permeability of the concrete and enhance its durability by extending the hydration of the cement, particularly in its surface zone see also provisions on curing under The target mean strength of concrete mix should be equal to the characteristic strength plus 1.

Attempts should be made to obtain the 30 samples, as early as possible, when a mix is used for the first time. As soon as the results of The construction should result in satisfactory strength, serviceability and long-term durability so as to lower the overall life-cycle cost. Quality assurance in construction activity relates to proper design, use of adequate materials and components to be supplied by the producers, proper workmanship in the execution of works by the contractor and ultimately proper care during the use of structure including timely maintenance and repair by the owner.

Some common cases should be specified in a general Quality Assurance Plan which shall identify the key elements necessary to provide fitness of the structure and the means by which they are to be provided and measured with the overall purpose to provide confidence that the realized project will work satisfactorily in service fulfilling intended needs.

The job of quality control and quality assurance would involve quality audit of both the inputs as well as the outputs. Inputs are in the form of materials for concrete; workmanship in all stages of batching, mixing, transportation, placing, compaction and curing; and the related plant, machinery and equipments; resulting in the output in the form of concrete in place.

To ensure proper performance, it is necessary that each step in concreting which will be covered by the next step is inspected as the work proceeds see also A Quality Assurance Plan shall define the tasks and responsibilities of all persons involved, adequate control and checking procedures, and the organization and maintaining adequate documentation of the building process and its results.

NOTE — Quality control charts are recommended wherever the concrete is in continuous production over considerable period. In batching concrete, the quantity of both cement and aggregate shall be determined by mass; admixture, if solid, by mass; liquid admixture may however be measured in volume or mass; water shall be weighed or measured by volume in a calibrated tank see also IS For large and medium project sites the concrete shall be sourced from readymixed concrete plants or from on site or off site batching and mixing plants see IS The material should be stock-piled for several hours preferably a day before use.

The grading of coarse and fine aggregate should be checked as frequently as possible, the frequency for a given job being determined by the engineer-in-charge to ensure that the specified grading is maintained. To this end, determination of moisture content in both fine and coarse aggregates shall be made as frequently as possible, the frequency for a given job being determined by the engineer-in- charge according to weather conditions.

The amount of the added water shall be adjusted to compensate for any observed variations in the moisture contents. For the determination of moisture content in the aggregates, IS Part 3 may be referred to. To allow for the variation in mass of aggregate due to variation in their moisture content, suitable adjustments in the masses of aggregates shall also be made. The mixers shall be fitted with water measuring metering devices.

The mixing shall be continued until there is a uniform distribution of the materials and the mass is uniform in colour and consistency. If there is segregation after unloading from the mixer, the concrete should be remixed. In addition, Curves or bends in prestressing tendon required by the designer shall be gradual and the prestressing tendon shall not be forced around sharp bends exceeding 1 in 6 both in plan and elevation or be formed in any manner which is likely to set up undesirable secondary stresses.

The minimum radius of curvature for curved cables shall be specified to ensure that bursting of side cover both perpendicular to the plane of curvature and in the plane of the ducts do not take place.

Hard-drawn wire used in prestressed concrete work shall be continuous over the entire length of the tendon.

IS1343 2012

Under factory conditions flame cutting may be permitted. Any trimming required shall be done only after the bar has been tensioned and the grout has set; it shall then be carried out in accordance with Furthermore, the internal surface of duct, prestressing steel and anchorage shall be protected by following methods in suitable combination depending upon severity of environment and extent of layers of protection considered desirable: The space between sheathing and duct can be filled with corrosion inhibiting materials like grease and wax.

For selection of appropriate method, material specifications, installation process, etc, specialist literature should be referred to. In addition, the material, strength and environmental resistance of the ducts forming external enclosure shall provide adequate mechanical strength and stability against environmental attack, including solar radiation. The ducts should be strong enough to resist pressure from the grouting operations.

The steel inside ducts is best protected in long terms by cement grouts which are properly executed following recommendations given in The protection by grouting can be further augmented by use of methods given below: However, bond between sheathing and concrete and sheathing and grout shall be adequate as needed by design. External parts of anchorages and projecting cables should be covered by suitable casing and protected by suitable material and method. Use of proper packaging and provision of externally applied passivating agents, oil films, etc, which is carried over in factory itself is recommended.

While providing protection by pressure grouting of cement, care should be taken that the neighbouring cables are not penetrated by grout. In case of doubt such cables shall be grouted in immediate sequence before the earlier grout could have set.

[PDF] IS : 1343 – 1980 CODE Book Free Download

If the earlier stressed cables are not grouted to avoid this problem, they should be protected by periodic flushing by oil-water mixture as given in b. It is the dimension used in design and indicated in drawings. The vertical distance between groups shall not be less than 50 mm. In case there is possibility of obstruction of flow of concrete or in case of severe exposure condition, horizontal grouping should be avoided. They shall be in as long lengths as practical from handling and transportation considerations without getting damaged.

They shall conform to the requirements specified in B-3 and B-4 and a test certificate shall be furnished by the manufacturer. The tests specified in B-4 are to be performed as part of additional acceptance tests for prestressing systems employing corrugated HDPE sheathing ducts and are not meant for routine site testing purposes.

The tension apparatus shall be such that it facilitates measurement and control of application of force. The tensioning apparatus should be independently supported so that it does not induce any undesirable secondary stresses. The prestressing wires may be gripped singly or in groups. Gripping devices shall be such that in a tensile test, the wire or wires fixed by them would break before failure of the grip itself.

The device shall enable the transfer of prestress to be carried out gradually so as to avoid large difference of tension between wires in a tendon, severe eccentricities of prestress or the sudden application of stress to the concrete.

The prestressing shall be controlled by measuring both the force applied to the tendon and the elongation of the tendon. Stressing schedule shall be incorporated in the design, which may include the following: The initial tension required to remove slackness shall be taken as the starting point for measuring elongation. Further increase of tension shall be carried out in suitable steps and corresponding elongations noted.

The magnitude of initial effective elongation corresponding to initial tension applied to remove slackness shall be obtained from the recorded and linearized portion of measured tension- elongation relationship and added to the measured elongation to give the total elongation. Alternatively, the same correction can be carried out graphically as shown in Fig. In such cases either the force or the elongation will be achieved first and the other value lag behind.

In such cases the force or elongation shall be further increased, but not exceeding 5 percent of the design value till the elongation or force , which If, even after reaching 5 percent extra value of the force or elongation , the other lagged quantity does not reach the design value, reference should be made to the designer for review and corrective action. It is essential that both methods are used jointly so that the inaccuracies to which each is singly susceptible are minimized.

Due allowance shall be made for the frictional losses in the tensioning apparatus. Further, whenever there is a breakage of tendons, the calibration shall be carried out before reuse of the gauges. The pressure gauges shall be accurate within 2 percent of their full capacity.

If the breakages are more than 2.

Wire breakages after anchorage, irrespective of percentage, shall not be condoned without special investigations. The grout ensures encasement of steel in an alkaline environment for corrosion protection and by filling the duct space, it prevents water collection and freezing. No sea or creek water is to be permitted. In case the internal diameter of the ducts exceeds mm, use of sand may be considered.

The mass of sand in the grout shall not be more than 10 percent of the mass of cement, unless proper workability can be ensured by addition of suitable plasticizers. Admixtures shall not contain chlorides, nitrates, sulphides, sulphites or any other products which are likely to damage the steel or grout.

When an expanding agent is used, the total unrestrained expansion shall not exceed 10 percent. Aluminium powder as an expanding agent is not recommended for grouting because its long-term effects are not free from doubt. For this purpose special openings should be provided where such openings are not available at end anchorages. For draped curved cables, crown points should have a grout vent.

For draped cables longer than 50 m grout vents or drain holes may be provided at or near the lowest points. It is a good practice to provide additional air vents at suitable intervals. All grout openings or vents should include provisions for preventing grout leakage.

Ducts should be securely fastened at close intervals. All unintended holes or openings in the duct shall be repaired prior to concrete placing. The joints of the couplers and the sheathing should be made water proof by use of tape or similar suitable system capable of giving leak proof joints. Grout openings and vents shall be securely anchored to the duct and to either the forms or to reinforcing steel to prevent displacement during concreting operations due to weight, buoyancy and vibrations.

Care shall be taken to avoid any damage by rough use of internal vibrator. Such local damage shall be repaired using tape to make it water tight to prevent ingress of slurry from the fresh concrete. The grout pump shall be fitted with a pressure gauge to enable pressure of injection to be controlled. The minimum pressure at which grout should be pumped shall be 0. The slower rates are preferable as they reduce the possibility of occurrence of voids. If the capacity of the pump is large, it is usual to grout two or more cables simultaneously through a common manifold.

Use of hand pumps for grouting is not recommended. Use of compressed air operated equipment for injection is prohibited as it is likely that there will be some air entrapped in grout. In case of any problem in grouting the ducts, such pump shall immediately be connected to the duct and all grout flushed by use of high pressure water flushing. It is, therefore, necessary to have adequate storage of clean potable water for operation of the water pump for such emergencies. Prior to introduction into the grout pump, the grout should be passed through such screen.

This screen should be easily accessible for inspection and cleaning. This ratio should not normally exceed 0. Before grouting, the properties of the grout mix should be tested in a laboratory depending on the facilities available. Tests should be conducted for each job periodically. The recommended test is described below.

The compressive strength of mm cubes of the grout shall be not less than 27 MPa at 28 days. Cubes shall be cured in a moist atmosphere for the first 24 h and subsequently in water.

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These tests shall be conducted in advance to ascertain the suitability of the grout mix. Chlorides from all sources, that is, cement, water, sand, fillers and admixture should not exceed 0.

The materials should be measured by mass. Water should be added to the mixer first, following by cement, and sand, if used.

Admixture, if any, may be added as recommended by the manufacturer. Mixing time depends upon the type of the mixer but will normally be between 2 and 3 min. However, mixing should be for such a duration as to obtain uniform and thoroughly blended grout, without excessive temperature increase or loss of expansive properties of the admixtures.

The grout should be continuously agitated until it is injected. Once mixed, no water shall be added to the grout to increase its fluidity. Hand mixing is not permitted. Whenever this stipulation cannot be complied with for unavoidable reasons, adequate temporary protection of the steel against corrosion by methods or products which will not impair the ultimate adherence of the injected grout should be ensured till grouting.

The sealing of the anchorage ends after concreting is considered to be a good practice to prevent ingress of water. For structures in aggressive environment, sealing of the anchorage ends is mandatory. Water used for flushing should be of same quality as used for grouting.

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