Concrete Construction Technology

Translator:LI Xue-mei，DAI Qian

(Chongqing YUCAI Project Supervision Limited Company，Chongqing 400074)

Ⅰ.Try mixing

1.General description

According to specification，trail mixing will be done.Data of mix ratio in plan and result will be submitted to the Engineer for approval.The Engineer will inform the contractor the approved structural ratio.

The Engineer will modify concrete material ratio at any time during contraction according to the site result.

The ratio decision made by the Engineer does not remove the duty of contractor of producing and concreting according to specification.Prior to any structure or part of mix concrete，the contractor will totally produce and pour concrete agreed with specification for the Engineer’s approval.

The table 1 summarizes the various types of concrete used in the project.

Tab.1 The various types of concrete used in the project

Different grades of concrete compatible with previous table will be used during construction，complying with international or national standard，or other standard approved by the Engineer.The previous table is regarded as guide，and other mix can be used when required.

According to test treatment of the Contract 5.1.4，press strength of concrete of 28days will be less than 95%of 80%of design strength，and less than 75%over design press strength.

Cement content above mentioned is just trail tested.During construction，the Engineer will instruct the contractor to change cement content of any concrete type.

Various structures for specified herein，the principle provisions of the concrete type to use in the table 2 and basic drawings.

Tab.2 Various structures for specified herein，the principle provisions of the concrete type

2.Trial mixing

Concrete construction of permanent structure will be ahead of set out for 60days.The contractor will mix each concrete though aggregate produce，dosage and concrete mixing equipment，until concrete complying with specification will be produced.

Ⅱ.Concrete and concrete material test

Unless otherwise specified，samples of concrete material，new mixing concrete and hardened concrete and test will be executed by the contractor complying with international or national standard，or other standard approved by the Engineer.The test of concrete aggregate，new mixing concrete and hardened concrete include，but not limit to the Tab.3.

Tab.3 The test of concrete aggregate，new mixing concrete and hardened concrete include

The contractor will carry out regular concrete test to ensure press strength，slump，air content and unit weight.Quantity of new mixing concrete and frequency will follow the Engineer’s instruction，in case that at less a test will be done to check concrete produced in a shift.Press strength of each concrete type will be tested by use of trial pillar，15cm in diameter 30cm in length，in a shift.Three samples of 7thand 28thday will be needed.Test of concrete aggregate will be carried out by the Engineer’s direction.Regular test result will be submitted to the Engineer in the approved table.

The test of concrete material，new mixing concrete and hardened concrete will be checked at any time if the Engineer consider necessary.The contractor will fully assist the Engineer of the test.

The contractor will provide necessary equipment，material and labor，produce，treat and check the trial sample according to this chapter and spoil matter will be handled.All concrete content，aggregate plant，dosage and new mixing concrete of batch plant will be sampled when pouring concrete.All dosage and batch plant will be equipped with sampling equipment approved by the Engineer.Such equipment will be often used，the design will ensure minimum interfere of the produce for aggregate and concrete by sample taking of proper size.

Ⅲ.Dosage

1.General description

The contractor will install，maintain and run mixing plant，equipped with automatic batching and recording systems to identify and control all materials within specified accuracy range，including concrete，water，cement，admixture，fine aggregate and each size of coarse aggregate.

The device will mix aggregate，cement，admixtures and water within the limit time into a uniform mixture，and unloading the mixture without segregation.The complete assembly line of the workshop will include convenience to check all operating facilities at any time.The workshop will be subject to the approval of the Engineer.

In spite of admixture measured by volume，each material will provide a separate weight batcher.Adequate facilities will be provided as to precisely check and control each batch of concrete.

The measuring equipment will quickly adjust to compensate for aggregate moisture content and change concrete mix effectively.Sand weigh hopper will be equipped with electronic device approved by the Engineer for the detection of fine aggregate in the moisture content changes.The sensing element of this equipment will be located near the loading port of the sand hopper，and the indicator of this equipment will enable the operator and Engineer’s easy observation.

Proportioning bin construction will be self-clean at discharge no less than once a week to be completely empty.Materials will be pumped directly from the discharge port of the top of the proportioning bin.If the coarse aggregate drop height is over 1.5m，it will be pumped through effective stone ladder.

The structure，maintainance and operation of the equipment for mixed material transporting from ingredients positions or hopper to the mixer will not scattered or contaminated materials with a good or overlapping ingredients.The equipment that can not satisfy this specification will be effectively modified or replaced in order to achieve the requirements of the Engineer.

2.Calibration of measuring equipment

Otherwise the Engineer’s approval，the equipment for measuring water，cement and admixtures will be checked at least once per two weeks，and the equipment for proofreading test and measuring the fine aggregate and coarse aggregate will be checked at least a month in the presence of the Engineer.After proofreading test，before further use of the measure or recording equipment，the contractor will make adjustment，repair or replacement for the possibility that the Engineer might satisfy.

The contractor shall provide standard test weight and other auxiliary equipment needed to check each scale or the operational performance of other measuring equipment.Periodic tests will be done in the presence of the Engineer in accordance with the manufacturer’s instructions，test methods and interval will be in the approval of the Engineer.

3.Batching and weighing equipment

Each weighing equipment will include a dial without spring，which can record load at any stage during weighing，or with a high/low indicator displaying weather non-load or load to a beam balance is in a state of equilibrium.The weight of each batch of ingredients will be automatically recorded，and the record will be submitted to the engineer in the interval directed by the engineer.

The construction and accuracy of weighing and measuring equipment will meet the requirement to maintain accuracy within 0.4%of the balance weighing range.

Each weighing indicator and water measure equipment will be within sight of the operator，the layout of the weighing equipment will allow the operator easily observing the operation of the doors and materials discharge to the mixer.The arrangements for controlling measure and mixing operations will meet the batch of material to finish unloading before a new batch of material can be loaded in mixer.

The construction and layout of dispensing equipment will control the sequence and timing of the discharge port in the ingredients positions to blend aggregate，water and cement drop through the hopper into the blender.Batching control will be interlocked so that the hopper completely emptied in order to start a new batching cycle.

Hopper structure will allow easy removal of over heavy material which is over specified tolerance，and will provide qualified facilities to take material from the ingredients in a representative sample of a test.

The operation mechanism of water measure facilities will be no leakage when the valve is closed，and after the feed valve is closed，the discharge valve will be opened.

The equipment for pulsing admixture will be linked with the ingredients of water and discharging operations，automatically batching and unloading of the admixture.Measure equipment of cement will be automatic.

Dispensing equipment will include automatic batching record components.Parts of the records will be printed in a continuous chart to output the following details:

Date and time of the dosage;

Dosage lot number;

Concrete type;

Each batch of material and the daily total weight;

And each batch of material and the weight of each material，such as cement，coarse aggregate，fine aggregate，water and admixtures.

Ingredients permissible error the Tab.4.

Tab.4 Ingredients permissible error

4.Mixture

The various ingredients of concrete will be mixed in the batch mixer of electric drive to output consistent homogeneous body.The mixer type shall be subject to the engineer’s approval.The mixer should be maintained in proper working condition，and the wearing parts will be periodically replaced.The mixing efficiency test will be approved by the engineer on a regular basis，all necessary adjustments or repairs will be done by the contractor.

Do not using manual mixing in permanent structure.If a temporary structure is used，it will be strictly in the engineer’s approval.

Each batch of material shall not exceed the rated capacity of the mixer normal continuous operation，the speed gap between the speed of rotation and recommended by the manufacturer shall be controlled in 1rpm range.Material composition should be put into the mixing tube in order to ensure the most efficient use of mixing time and avoid the loss of material.

In the case that the material composition of the stock is not fully confirmed，there is a reasonable margin of safety to complete a specific concreting，and mixing concrete shall not be started.

Unless the engineer approves or has another indication，each batch of the mixing time shall not be less than the time listed in the table 5，unless the full amount of water and admixtures are put into the mixer.

Besides，after all the water needed join the mixing tube，stirring should continue for at least one minute.

The minimum mixing time mentioned above is assumed in the case of correctly control of the rotational speed of the mixer and materials，including water，having been added into the mixer.If the engineer considers that feed and mixing operations faille to produce the required homogeneous mixture and consistency，the mixing time will be increased.

Tab.5 Each batch of the mixing time

The effect of mixing operations should be determined by measuring the unit weight difference of mixing mortar in material mixer，and be consistent with international standards，or with national standards by equivalent standards with international standards requirements，and this national standards will be approved by the engineer，or other standards approved by the engineer.The first part and last part of the compound discharged from the mixer to take two air mortar samples，the differences between its unit weight and the average weight of the two mortar samples shall not exceed 1%.Moreover，among samples of the first part and the last part of the compound unloading from the mixer，the volume of each sample is 50 liters.The difference between coarse aggregate weight of per cubic meter and the average weight of the two coarse aggregate samples should not exceed 8%.These measurements are done by the contractor.

The partial hardened concrete will not be re-mixed whether it is plus or without additional cement，aggregate or water.

The mixer will be regularly cleaned to the approval of the Engineer.

Ⅳ.Transport and pouring equipment

After discharging from the mixer，the method of concrete transportation should be approved by the engineer.Placement will be done within an hour water will be added to the mixing barrel.

Concrete transport methods and equipment should be used to deliver the concrete of required components and consistency to the casting position.There is no adverse segregation，collapse loss is no more than 2.5cm，and the air content loss does not exceed 1% ，or otherwise is approved by the engineer.

The concrete discharged from the mixer will not be added water or“re-mixed”.

If concrete is transported by the following conveyance，such conveyance shall meet the following requirements:

1.Agitator truck

The stirring speed of the agitator will be between 2rpm and 4rpm.The concrete volume in barrel shall not exceed the manufacturer’s rated capacity，nor more than 70%of the volume of the cylinder.The time interval between adding concrete to agitator truck and discharging will not exceed 1 hour.During intervening period，the agitator will be stirring continuously by that speed mentioned above.If approved by the engineer，the car mixer will be used instead of the agitator truck for transporting concrete aggregate from center plant，and stirring at site.

2.Sliding Road

In general，otherwise is approved by the engineer，slip Road will not be used for transporting concrete.Chute crosssection will have round corners，appropriately installed slope will be used for concrete successfully shedding，without segregation.The low-end shall be equipped with a whereabouts slip Wan Road of height of less than 0.6m to avoid segregation of the whereabouts concrete.Slip Wan Road will be protected from direct sunlight and wind and rain.

3.Concrete pump or casting machine

Categories and work ability of the pump or the casting machine should meet the specification，and the planned speed，construction progress;quality of concrete，concrete pouring location will be taken into account.The transport pipe diameter shall be not less than three times of the maximum size of aggregate used in concrete.

The transport pipe installation shall allow for easy removal.The piping layout should maintain the line as straight as possible to prevent the blockage of the concrete mixture in the pipeline.Support stiffness of the pipeline will be sufficiently stable for pipeline fixing，and will not adversely affect templates and steel bar already in place.Care will be taken to prevent concrete mortar leakage from pipe joints.

Before the pump or casting machine start，the 1m3mortar will pass the pipe first，with the same proportions of water，admixtures，cement and sand as normal concrete mix design.

Pressurized air will not be used，unless the pipe outlet is completely buried in fresh concrete at least 2m.

4.Belt conveyor

Otherwise approved by the engineer，belt shall not be used to convey concrete.The belt conveyor will be under good protection from the sun，wind and rain.At each end of the conveyor there will be proper feeder or vertical sliding Wan Road，with at least a depth of 0.6m.Concrete falling distance is no more than 1.5m.

5.Barrel

Drums will meet requirement of non-segregation when concrete is transported to the casting position.The barrel will be equipped with soft inclined tube with a height of no less than 0.6m.Concrete falling distance will be no more than 1.5m.

Ⅴ.Concreting

1.General description

At least 30 days before the start of the concreting of the permanent works，the construction program will be submitted to the engineer for approval by the contractor，the concrete pouring methods will be explained in the program plan.

The contractor shall report concrete pouring daily progress to the engineer at any time.Concreting should be carried out in the presence of the engineer.

All the template works，embedded parts and casting involving surface preparation work will be completed by the contractor.Pouring concrete will be done after the engineer checks and approves.

A checklist shall be submitted to the engineer by the contractor to assist the engineer to check.After approval，the engineer will sign the list.The list is then used for quantity estimates.

Otherwise approved by the engineer，concrete shall be cast in the rain or water.In any case，concreting will not be in running water.

The color of concrete will be well-distributed in the structure，and external concrete surfaces exposed to the public will not be allowed color mutants.The contractor shall，as far as possible to ensure the color uniformity of the surface，where permitted color change can be gradual.

If necessary or required，the contractor shall provide communication facilities between the mixing plant and the casting site approved by the engineer.

2.Pouring preparation

Before concreting，concrete bonding surface of the rock foundation should be cleaned by high-speed gas-water jet or other effective way approved by engineer，removing oil，dirt，organic matter，wood，hazardous coatings，debris loose rock debris or other hazardous substances.

Faults and cracks should be cleaned to meet the requirements of the depth，and the sides need to reach the hard rock.

Before pouring the concrete，the surface of the rock foundation should be thoroughly wet for at least 18 hours，and stagnant water should be removed.

The surface of soil or sand and gravel foundation to be poured concrete should be no still water or running water，wood，or other such harmful substances.To soil or sand and gravel foundation，foundation should be wet before pouring concrete.

The surface of construction joint of old concrete，including pouring new concrete on which to block the surface，should be roughed and cleaned by chisel，high-speed gas-water jet，wire brush or other approved methods，and after using the above method，casting concrete moist will be kept for at least 18 hours.

Cleaning should include the removal of all laitance，soft or defective concrete coatings and foreign matter.

Things attached to concrete or other foreign body，will be thoroughly cleaned in the surface of all expansion joint，by scraping with a chisel or otherwise method approved by the engineer.Expansion joints should be covered with asphalt paint or other compounds approved by engineer to prevent bonding.

3.Pouring

After All surfaces are well-prepared complying to the specification，all construction joint close to the level of the rock surface and mass concrete shall be paved a layer of sand excess mixture.The proportion of cement and sand mixture should be approved by the engineer.Excessive sediment mixture is evenly spread，with the thickness of 1.5cm to 2cm，and the concrete should be immediately cast above.

Hardening can not guarantee the correct casting unless the re-mixing concrete should be removed and set aside as disposal and cost is borne by the contractor.

Whenever possible，concrete should be directly discharge in its final position to avoid flow in prevention of segregation.Methods and equipment to unload the concrete in the template should not make the separation of the coarse aggregate from main part of concrete.Vertical free fall distance of concrete shall not exceed 1.5m.Concrete going through reinforced bar will be careful poured to minimize segregation.

In addition to the lining of the underground structure，all formed concrete should be cast in accordance with horizontal layers，and the thickness shall not exceed 0.5m.The height of concrete pouring layer will not exceed 1.5m，unless the engineer otherwise approved.The time interval of the continuous casting of all structures will be at least 24 hours.For the bulk structure，if approved by the engineer，this time interval can be extended to 96 hours.

Cold joint should be possibly to avoided.If the device fails，or other reasons interrupt the continuous casting，the full consolidation of the concrete joint shall be done by the contractor in the time that concrete can be plastic to form a uniform and stable slope.Such cold joint surface of the concrete construction joint should be cleaning and wetting in the fresh concrete cover.

Removing the braces，struts and pillars should be cast in concrete to a certain height，when they are no longer needed for temporary support template.Keep the location of the template，correct shape and alignment.These temporary components except the metal should be thoroughly removed from the template and not be buried in concrete.

Unformed concrete pouring on the slopes，in the case that the slope is too steep，make it impossible to achieve vibration to form concrete.Concrete should be cast before an undetermined length of the sliding mode model，a model from its cutting-edge extending back to about 80cm.The concrete should be in front of the sliding mode model tamping to ensure that the sliding mode is completely filled with plug-in vibrators.

If the monomer concreting around the open structure of the vertical dimension is greater than 60cm，or casting platform，floor，roof panels，beams，trusses，or other similar structure，the provisions are as follows:

1)At the top of the open architecture platforms，flooring，beams，trusses，or other similar structure of the bottom of the incline slope should be delayed one hour or more，or less than three hours.In any case，casting shall not be delayed too long to penetrate before pouring the concrete so that tamping parts can not rely on its weight.Compacting concrete will be poured in after delay，the tamping parts should be through the pouring of concrete and re-vibration delay.

2)Before delay of the last 60cm or more concrete casting should be as low as possible to collapse and the contractor shall ensure that the concrete is completely compacted.

3)After delay and before pouring the concrete，concrete surface should be clean，without any loose concrete or foreign body.

4)Casting in an open structure and concrete of platforms，flooring，beams，trusses，or other similar structure should be as low as possible to collapse and pouring，and the contractor shall ensure that concrete is completely compacted.

Unless the engineer is otherwise approved，the lining of the underground structure of the concrete should be concrete pumped or a casting machine casting a non-high-speed discharge to the template.The concrete should be pushed all the irregular rock surface to ensure that there is no gap.If concreting of invert，sides and crown is separately poured，without internal template，so pneumatic casting equipment will not be used，which will not lead to segregation models.Casting equipment should be used only by experienced personnel operations.

4.Concrete temperature

The concrete pouring temperature shall not exceed 32℃.If the engineer deems it necessary，the contractor shall take effective measures，such as pre-cooling the mixing water，add ice to the mixing water or borneol，pouring in the night，or a combination of several methods in order to maintain the temperature in the pouring of concrete below 32℃.

5.Vibration

Each layer of concrete should immediately vibrated by proper equipment，so that the concrete is compacted to the maximum possible density，and tight fit in the template and buried surface of the material.After completing the required previous layer，the subsequent layer will be poured.

In general，concrete should be used pneumatic plug-in vibrator tap inserted in the concrete work at least as fast as 7000 rpm.The head of vibration should be vertically inserted in the lower layer of concrete at least 5cm.If it is difficult to use plugin vibrator，concrete can be compacted by external vibrators tap or manual plunger，according to the approval of the engineer.External vibrator should be used by a speed of 8000 rpm，and must be large enough to tap.

The spare vibrator will be retained to replace equipment that does not work.

Be careful to avoid the vibration head from coming into contact with the template or embedding in the surface of the component in order to avoid local vibration excessive.The vibrator should be systematically used，the spacing should allow the affected zone of overlap and the concrete for correct compaction.Over-vibration should be avoided for leading to segregation and laitance layer，or the tendency of too much water to the surface.

Ⅵ.Protection and curing of concrete

The contractor shall protect the concrete to avoid damage or harmful effects by sudden drying，loading，shock or vibration until the concrete is fully hardened enough to prevent damage.The bare surface of completed concrete should be protected from direct sunlight at least three days after pouring.

Water conservation or film conservation of all mortar and concrete surface should be done by engineer’s approval.

When the unformed top surfaces of thick block of wall and buttresses harden to avoid water covering materials from producing damage，saturated with water or other effective means will be applied to maintain infiltration.These surfaces and steep surface and vertical forming surface should be removed.Before and after removal，the unformed top surface will be maintained complete and sustained wet，and allow water in the formed and unformed concrete surface.This procedure should be followed by the provisions of the water conservation or film conservation.

Requirements of water and film curing are as follows:

1.Water curing

Water conservation used for concrete will immediately kept wet after concreting at least 14 days until the new concrete coverage.Moisturizing method is a coverage with water-saturated material(sand，burlap，etc.)，or perforated pipes，mechanical sprinklers or porous soft pipe system，or other engineer approved to maintain the surface of continuous(not regularly)moist.For the water used for conservation should not contaminate with oil and salt.Water conservation treatment should prevent the concrete surface to form being unsightly blemishes permanently exposed to the outside.

2.Film curing

Film conservation should use a approved conservation compounds type in white color，impermeable film forms on the concrete surface;premise is permanently exposed to the sight on the concrete surface with approved material used in forming surface approved by the engineer.The curing compound shall be sprayed layer to form a continuous and uniform coating on the concrete surface in all regions，and the maximum coverage area per liter will be determined according to the roughness of the surface to be covered by the engineer.If necessary，in order to fully cover the surface，by the engineer’s approval，should apply to a second layer of the conservation of compounds.Before spraying conservation compounds，the mortar dirt and burrs on the surface will be cleaned.

If curing compounds to be used in the unformed concrete surface，after the completion of the last process the compound spraying should begin immediately.

If the conservation of compounds to be used in the forming of the concrete surface after removing the template should be immediately sprayed a small amount of water to wet the surface and keep moist until more water cannot be absorbed by the surface.Curing compounds should be in the surface water layer just disappear while the surface is still wet spraying.In forming the edge of the surface，corners and uneven point there must be adequate coverage of the compounds.Maintenance compound construction is completed，the film feels dry，and it should be repaired according to requirements of the concrete surface.After completion of repair，complying with the foregoing requirements，moist and conservation of compounds will used for covering.

Spraying equipment and spraying of curing compound shall be subject to engineer approval.

If the surface of the curing compounds cannot avoid the traffic after，the film with a thickness of no less than 25cm or other effective measures for protection.

The conservation plan to use the compound types should be sampled and checked prior to at least 30 days for the engineer.Otherwise the engineer cancels the sampling and testing，the conservation of compounds should be used after tested and approved by the engineer.The engineer shall provide the facilities and necessary assistance to the conservation of compound trials，and shall report thereon to the employer to ask for money.Storage，mixing and application of curing compounds should follow the manufacturer’s instructions.

In addition to the spray film conservation，plastic film，especially the conservation of the thick block and structural steel will be used.In this case，the hardened concrete will be enough to avoid damage，and shall be immediately sprayed water to the surface，then completely be covered with plastic film in the surface approved by the engineer.The film should be hermetically sealed，non-polluting and no leakage of steam to effectively avoid moisture evaporation loss.Film will be carefully overlapped and sealed at the edge.The maintenance work of film should be maintained for at least 14 days.

If necessary to delay the pouring of new concrete on construction joint，all construction joints shall use water conservation to maintain a continuous wet，no matter how much time it will take until they are covered by concrete.Joint surface can be interrupted after the end of the normal provisions of the conservation of wetlands conservation;wet curing is interrupted，it should be sewn onto the start pouring new concrete at least 48 hours before re-start.

Adequate protection shall be used to avoid damage.Whenever near the concrete or in direct contact with the concrete has a fire or overheating，including the heat generated by welding steel or reinforced.Concrete conduit and other openings facilities should be closed throughout the maintenance period.

Ⅶ.Construction joints

The location of construction joints shall be according to drawings or engineer’s approval.

The location of construction joints shall be according to drawings shown or engineer for approval.

The joint should be in a pillar under the slab or beam at the top of the foundation and floor.The pillars of the arch of the axils and capitals pallet should be together with the slab casting.The seams should be perpendicular to the main reinforced.Walls and columns，pouring layer on the surface should be level.

Construction joint surface should be prepared to accept the subsequent concrete pouring layer by abrasive blasting，all cement laitance and loose or porous material will be removed by high-speed gas-water jet，wire brush or other approved method of cleaning and playing hair.After trimming，as long as the outflow of cleaning water is cloudy，the surface should continue cleaning erosion.Before the follow-up concrete is about to pouring，surface should be cleaned by re-gas-water jet.

If the concrete has been pouring over four hours but less than three days，just before pouring the new concrete，cement mortar layer about 10mm thick coating should be used of the same consistency of concrete mixture.

Pouring concrete over three days should be used of play hair，high pressure water jet or wet the sand，so that no cracks or loose aggregate of strong and uniform concrete surface will bare.This surface should remain wet for at least 48 hours before pouring new concrete.Pure water slurry consistency will be similar to thick cheese before pouring new concrete，it should be applied to the prepared surface，and then used a layer about 10mm thick coating consistency the same concrete mixture of cement mortar.

For trimming，washing and cleaning of concrete surface wastewater treatment，wastewater will not affect exposed structures on the surface by contamination，discoloration，or affect.

Ⅷ.Contraction joint and water seal

Basic drawing shown or approval of the engineer of the contraction of other parts of the seam should be provided by the contractor.In the first layer of the concrete surface，joint materials should include a layer of asphalt coating or other approved material.

The water seal of type A or B shall be provided by the contractor，and installed in the basic drawing shown or position approved by the engineer.Water seal should be made of soft PVC，in line with the requirements of international standards or requirements by the equivalent standards with international standards，these Chinese standards approved by the engineer or the engineer approved standard.Here the provisions of the water seal should include only lodicules.

Ⅸ.Formwork

1.General description

Where special requirements engineer need should use the template to limit the line of the concrete to shape.

The template should have sufficient strength and rigidity to support concrete and bear the pressure generated by the pouring and vibration，and will not deviate from the prescribed line.All templates in contact with the concrete surface should be clean，rigid，smooth and dense enough to prevent mortar loss.

Unless the engineer is otherwise approved，all exposed joints，edge and exterior angle should be made of shape with 45 degrees at least 2cm of the chamfer.Angles shall indicate the place or supervision required by the engineer.

Before concreting，observation of the correct position of all of template will be done，and template support has been adequately and securely fastened.

The template project should be classified by concrete surface finish smooth，such as basic drawing shown.Concrete surface finish requirements for the F3 and F4 of template should not be continuous construction，from pouring layer should be in a cast layer of concrete to harden，put under heavy cast layer.The location of the template rod hole should be the standard pattern layout in the template pre-construction approval by the engineer.Replay template should overlap with the previous layer of hardened concrete pouring，but not more than 30mm，and fit closely with the hardened concrete，so that the re-start pouring concrete，the template will not release the construction joints of the mortar will not be offset or loss.If necessary，should use extra bolts or template rod fixed replay template with hardened concrete tight fit.All joints and grooves is flat indeed.

Matted before the manufacturing template design approved by the engineer.This should include all types of contractor plans to use the standard plate.

2.Material

The materials usedin the template，whether it is steel or wood，should be approved by the supervisor.The timber shall be firm，straight，no warping，rot and soft nodules and shall be smoothly processed in front of the assembly template and uniform in width and thickness.

The template in the waterways and that will eventually be exposed to the sight shall use the plywood or steel without any defects in the concrete surface.

If you use plywood，it should be no warping，wrinkling，and use special waterproof glue manufacturing.The width and length of the plywood should be unified as much as possible.

The type and quality of wood or inside lining，or after treatment or coating，shall meet that forming concrete surface does not produce chemical deterioration or discoloration.The type and status of the templates cover plate and inside lining，the deformation capacity caused by the template resistance of concrete pouring and vibration as well as the template construction process meets the requirements of in these specifications forming surface and the forming surface finish.

Surface finish requirements should be used for the F4 concrete formwork plywood sheathing or lining，covering an approved plastic or epoxy，and try to use a large piece of sheet metal.The extra hole should be cleaned and neatly blocked before re-using the template each time，the surface of where it is needed to re-do the coating.

3.Construction tolerance

Compared with the basic drawings shown in the alignment of the structures，slope and size，the differences of structure alignment，gradient and size should be within the tolerance range in the following provisions.The concrete works over the provisions of the tolerance limit herein should be removed，repaired and replaced at its own expense.