Tài liệu SECTION 06100 - CONCRETE AND CONCRETE STRUCTURES ppt

 ASTM C91 - Masonry Cement ASTM C123 - Lightweight Pieces in Aggregate  ASTM C136 - Sieve Analysis of Fine and Coarse Aggregates  ASTM C143 - Slump of Portland Cement Concrete  ASTM

SECTION 06100 - CONCRETE AND CONCRETE

STRUCTURES

TABLE OF CONTENTS

1 DESCRIPTION 1

2 STANDARDS AND CODES 1

3 MATERIALS 2

3.1 General 2

3.2 Cement 3

3.3 Aggregate 3

3.3.1 FINE AGGREGATES 4

3.3.2 COARSE AGGREGATE 5

3.4 Water for Concrete Mixing and Curing 6

3.5 Admixtures 6

4 CONCRETE CLASSES 7

4.1 General 7

4.2 Class Requirements 7

4.2.1 USES OF DIFFERING CLASSES OF CONCRETE 8

5 MIX DESIGNS 8

5.1 Samples 8

5.2 Mix Design 8

5.3 Adjustments During Progress of Work 9

5.4 Contents of Chlorides and Sulphates 10

6 WATER - CEMENT RATIO 10

7 TESTING 10

7.1 Slumps 11

8 FORMWORK 12

8.1 Design 12

8.2 Construction 12

8.3 General Requirements 13

9 CONCRETING 13

9.1 General 13

9.2 Placing and Compacting 14

9.3 Weather Precautions 16

9.4 Continuity of Concrete Work 17

9.5 Batching 17

9.5.1 PORTLAND CEMENT 17

9.5.2 WATER 17

9.5.3 AGGREGATES 18

9.5.4 BINS AND SCALES 18

9.6 Mixing and Delivery 18

10 CONCRETE PLACEMENT 19

10.1 General 19

10.2 Chutes and Troughs 19

10.3 Pumping 20

10.4 Vibrating 20

10.5 Concrete Consistency 20

11 JOINTS 20

11.1 General 20

11.2 Construction Joints 21

11.3 Bonded Construction Joints 21

11.4 Unbonded 23

11.5 Expansion Joints 23

12 CONCRETE FINISHING 23

12.1 Finishing Concrete Surfaces 23

12.1.1 CLASS F1 – FORMED SURFACE 23

12.1.2 CLASS F2 – FORMED SURFACE 24

12.1.3 CLASS F3 – FORMED SURFACE 24

12.1.4 CLASS F4 – FORMED SURFACE 24

12.1.5 CLASS U1 – UNFORMED SURFACE 24

12.1.6 CLASS U2 – UNFORMED SURFACE 24

12.1.7 CLASS U3 – UNFORMED SURFACE 24

12.2 Requirements for Formed Surfaces 25

12.3 Remedial Treatment of Finished Surfaces 25

12.4 Fixing of Ironwork 25

12.5 Reconstruction of Faulty Work 25

13 CURING 25

13.1 Supplying Additional Moisture 26

13.2 Preventing Moisture Loss 26

13.3 Waterproof Paper 26

13.4 Plastic Sheets 27

13.5 Curing Compounds 27

13.6 Forms

27 14 PLACING OF CONCRETE IN OR UNDER WATER 27

15 WATERSTOPS 28

16 TOLERANCES 29

16.2 Soffits 29

17 PRECAST CONCRETE ELEMENTS 32

17.1 General 32

17.2 Materials 32

17.3 Fabrication 32

18 MEASUREMENT AND PAYMENT 32

18.1 General 32

18.1.1 MEASUREMENT 33

18.1.2 Payment

33

 ASTM C91 - Masonry Cement

 ASTM C123 - Lightweight Pieces in Aggregate

 ASTM C136 - Sieve Analysis of Fine and Coarse Aggregates

 ASTM C143 - Slump of Portland Cement Concrete

 ASTM C144 - Aggregate for Masonry Mortar

 ASTM C150 - Portland Cement

 ASTM C227 - Potential Alkali Reactivity of Cement-AggregateCombinations (Mortar-Bar Method)

 ASTM C294 - Constituents of Natural Mineral Aggregates

 ASTM C494 - Chemical Admixtures for Concrete

 ASTM D1457 TFE-Fluorocarbon Resin Molding and ExtrusionMaterials

(c) Materials that do not comply with the requirements of thisSpecification will be rejected by the Engineer and removedimmediately from the Site of the Works unless otherwiseinstructed by the Engineer No rejected materials shall be used inthe Works

3.2 CEMENT

(a) The cement shall be portland cement Type I, complying in allrespects with ASTM C150 (AASHTO M85) All cement shall be

manufacturer’s standard grey cement unless otherwise specified

on the Drawings One brand of cement as approved by theEngineer shall be used for all concrete works throughout theproject unless otherwise authorized by the Engineer in writing.(b) The source of supply of cement shall be subject to the Engineer’sapproval and the Contractor shall at all times furnish themanufacture’s test certificates and proof that the specificationshave been complied with, together with a note of the date ofmanufacture, certified by an independent agency in the country oforigin The Engineer shall have the power to reject a part or thewhole of any consignment of cement if he considers it to beunsuitable for use in the Works

(c) Cement shall be delivered to the Site in sealed bags or water-tightbarrels bearing the manufacturer’s name, cement type and thedate of manufacture The bagged cement shall be stored in pilesnot more than eight bags high Storage areas shall be perfectly drywaterproof sheds or other such temporary buildings approved bythe Engineer The storage capacity shall correspond to the amount

of concrete required for the largest units to be cast Thesebuildings shall be used exclusively for the storage of cement andshall be erected with the floors raised well above the ground atplaces on or near the Site of the Works; and at the completion ofthe Works the buildings shall remain the property of the Contractorand shall be dismantled and removed, the foundations broken upand the site restored to its original condition by the Contractor.(d) A free passage of at least one meter shall be left between thecement and the side walls of the sheds Access ways shall also beleft between the stored containers of cement such that everycontainer is visible Each consignment of cement shall be storedapart form earlier consignments and consignments shall be used inthe order in which they are delivered Any consignment which hasbecome caked or otherwise adversely affected shall be removedfrom the Site completely at the Contractor’s own expense

3.3 AGGREGATE

(a) Aggregates shall be free of substances that are deleteriouslyreactive with the alkalies in the cement in an amount sufficient tocause excessive expansion of the concrete Aggregate acceptanceshall be based on satisfactory evidence furnished by theContractor that the aggregate is free from such materials This

(b) All aggregates shall consist of tough, hard, durable and uncoatedparticles The Contractor shall be responsible for satisfactorilyprocessing this material to meet the requirements of theseSpecifications Thirty days before starting work, the Contractorshall advise the Engineer of the sources of aggregates to be used

to permit samples to be taken in the presence of a representative

of the Engineer and the Contractor to test before being brought tothe Site Approval of aggregate quality and/or gradation shall notwaive the responsibility of the Contractor to fabricate concrete ofthe strength specified

(c) Aggregates shall be stored in such a way as to prevent segregationand contamination The center of the storage area shall be free ofexcess moisture Aggregate which has become segregated orcontaminated with foreign matter during storage or handling will

be rejected and shall be removed and reprocessed and/or replacedwith material of acceptable quality Aggregates shall be stored insufficient quantity to ensure that there is no interruption ofconcreting work at any time

(d) Both fine and coarse aggregates shall be tested in accordance withthe following standards:

 ASTM C39 Compressive Strength

 ASTM C40 Organic Impurities

 ASTM C87 Mortar Strength

 ASTM C88 Soundness

 ASTM C123 Coal and Lignite

 ASTM C136 Sieve Analysis(e) Approval of aggregates will not prevent later rejection if results ofsubsequent tests do not reflect compliance with the requirements

of the specified standards

(b) The fine aggregates shall be reasonably graded and shall meet thegrading requirements contained in Table No 1 below:

TABLE NO 1 Grading Requirements of Fine Aggregate

Sieve Size(mm)

Percent Passing by weight

9.54.752.361.180.6000.3000.150

(d) If required by the Engineer and in order to meet specificationrequirements, fine aggregates for use in reinforced concrete shall

be washed with fresh potable water

3.3.2 COARSE AGGREGATE

(a) Coarse aggregate shall be crushed aggregate for reinforcedconcrete works and unreinforced concrete works and shall behomogeneous, clean, free from extraneous materials, clay lumps,

be washed if it is unclean, or may reject any material that does notcomply with this Specification.

(b) The quarry from which the coarse aggregate is to be obtained shall

be approved by the Engineer before material is delivered to theSite of the Works

(c) Coarse aggregate shall meet the requirements of ASTM C33

(d) The coarse aggregates shall be reasonably graded and shall meetthe grading requirements in Table No 2 below

TABLE NO 2 Grading Requirements of Coarse Aggregates

ConcreteClass G andP

(e) The percentage of wear of the aggregate shall not be greater than

50 as determined by AASHTO T96 The coarse aggregate shallwithstand at least five cycles of immersion and drying in bothsodium sulphate and magnesium sulphate solutions, as prescribed

in the soundness test, and shall show an average weight loss ofnot more than 15 percent

3.4 WATER FOR CONCRETE MIXING AND CURING

(a) Unless otherwise authorized in writing by the Engineer, onlypotable water free from oil, salt, acid, sugar, vegetable matter orany other substance injurious to the concrete may be used for

of Type D as specified in ASTM C494 The Contractor shall beentirely responsible for the use of any approved retarder in strictaccordance with the manufacturer’s instructions.

(b) Retarders shall not be used together with other admixtures in thesame mix unless approved by the Engineer The fluid content ofadmixtures shall be considered in the determination ofwater/cement ratios

(c) Preliminary tests of cylinder strength and any other tests shall becarried out for all concrete with admixtures When the Engineerapproves changing the brand or type of cement, the Contractorwill be required to carry out further tests and establish a relativemix design

(d) Water reducing and water reducing-retarding admixtures, inaccordance with ASTM C494 and plasticizing and retardingadmixtures in accordance with ASTM C1017 may be used with thewritten permission of the Engineer in accordance with mix designsand slump requirements as approved by the Engineer

(e) Calcium chloride or admixtures containing calcium chloride will not

be permitted

(f) The Engineer shall approve the type of, amount of and place inwhich any or all admixture shall be used

4.2 CLASS REQUIREMENTS

(a) The approximate weights or volumes of the components for eachclass of concrete and any other data given in any table of thisSpecification are an aid for suggested trial mixes and may be ofvalue to Contractors in determining the approximate quantities ofcomponents required However, the minimum crushing strength ofthe Work Test cylinders at 7 days and 28 days must be strictlyadhered to Acceptance of the work by the Engineer will be based

on 28-day cylinder strength as determined in accordance withrequirements and procedures noted under this Specificationsection

(b) Concrete to be used shall include the properties and strengthrequirements contained in Table No 3 Method for TestingConcrete, AASHTO T22 and T23 (ASTM C31 and C39) shall governfor the manufacture of compressive strength test cylinders for allclasses of concrete

TABLE NO 3Composition and Strength of Concrete for Use in Structures

REQUIREMENT S

CLASS OF CONCRETE

Maximum Size

of Course Aggregate

Minimum Compressive Strength of 150

mm x 300 mm Concrete Cylinder at 28 days (MPa)

FlexuralStrengt

h at 28days5000kPaMinimum

Cement Content(kg/m3) 450 420 380 350 330 280 220 350

CLASS OF CONCRETE

Water CementRatio (Max.) 0.375 0.40 0.45 0.475 0.50 0.60 0.76 0.40Slump Range

(mm) 10050- 10050- 10050- 10050- 25-75 25-75 25-75 25-50

4.2.1 USES OF DIFFERING CLASSES OF CONCRETE

The class of concrete to be used in each part of the Contract works shall

be as called for on the Drawings or as directed by the Engineer

5 MIX DESIGNS

5.1 SAMPLES

Samples of all materials to be used in the mix shall be submitted to theEngineer and such samples shall be tested in site laboratories asdirected by the Engineer No materials forming any part of this mix shall

be delivered to the Site before the Contractor receives the prior writtenapproval of the Engineer for such material

5.2 MIX DESIGN

(a) After receiving written approval by the Engineer of the samples,the Contractor shall submit in writing to the Engineer a proposedmix design proportioned by weight and based on trial mixesconducted with the approved materials to be used for eachspecified class of concrete for the project

(b) No concrete works will be allowed to commence before theContractor receives, in writing from the Engineer, approval of theContractor’s proposed mix design

(c) The Contractor must make arrangements for all the foregoing asearly as possible and to allow the Engineer sufficient time toreview the design(s) and if necessary conduct and/or requireadditional strength testing

(d) In the event of any changes in characteristics or source of supply

of any of the component parts, a new mix design must besubmitted for approval by the Engineer as described Any delaydue to such changes will be entirely the responsibility of theContractor and no claims for delay or compensation will beconsidered During the currency of the Contract the Engineer can

5.3 ADJUSTMENTS DURING PROGRESS OF WORK

After a mix design has been approved, as prescribed above, theseproportions of the constituents of the mix design shall not be changedduring the progress of the work except as follows:

(a) Adjustments for variations in workability:

 If it is found impossible to obtain concrete of the desiredworkability with the proportions originally determined, theEngineer may allow changes in aggregate weights as he maydeem appropriate

(b) Adjustment for variation in yield:

 If the cement content of the concrete, determined by means

of the yield test ASTM Designation C 138, varies more thantwo (2) percent from the designated value, the proportionsshall be adjusted so as to maintain a cement content whichdoes not vary more than two (2) percent from the designatedvalue

(c) Adjustment for minimum strength:

 If it is found impossible to produce concrete having theminimum allowable strength specified, the cement contentshall be increased as directed by the Engineer

(d) Adjustment for new materials:

 No change in the source or character of the materials shall bemade without due notice to the Engineer

 No new materials shall be used until the Engineer hasaccepted such materials and new proportions based on thetests of trial mixes have been determined

5.4 CONTENTS OF CHLORIDES AND SULPHATES

The amount of chlorides in the concrete mass shall not exceed 1,000ppm when calculated on the total concrete mass, or 6,000 ppm whencalculated on the amount of cement in the actual mix The amount ofsulphate in the concrete shall not exceed 800 ppm when calculated onthe total concrete mass, or 5,000 ppm when calculated on the amount

of the cement in the actual mix For the above-mentioned calculations,

6 WATER - CEMENT RATIO

(a) The quantity of water used in mixing shall be approved by theEngineer on the basis of preliminary tests and trial mixes and shall

be the least amount that will produce a workable homogeneousplastic mixture which can be worked into the forms and around thereinforcement In no circumstances shall the consistency of theconcrete be such as to permit a separation of the aggregate fromthe mortar during handling Excess water shall not be permittedand any batch containing such excess will be rejected

(b) In measuring water for each batch of concrete, allowance shall bemade for the water contained in the aggregates The total water inthe batch shall be deemed to consist of the water carried by theaggregates plus the water added

(c) Frequent tests including the slump test shall be carried out toensure that a consistent water content is maintained

7 TESTING

(a) In addition to all previously mentioned tests, the following testsshall be carried out All tests must be carried out in a manneracceptable to the Engineer and shall be conducted by theContractors Independent Laboratory The Contractor shall bear allexpenses involved in obtaining, cutting-out or sampling allspecimens and/or component parts for testing

(b) Test cylinders shall be taken for each new grade of concrete orfrom each 100 cubic meters of concrete when the same grade isbeing used continuously, or as directed by the Engineer Nine (9)test cylinders shall be taken at each time and each numberedconsecutively and marked with the date, the section of work fromwhich it was taken and any other information required anddispatched to the approved laboratory for testing for compressivestrength Cylinders Numbers 1,5 and 9 shall be tested after 7 days.(c) If the average of the three 7-day test cylinders is below 75 percent

of the minimum 28 day requirement, the Contractor mustimmediately stop all concreting until checks are made on thematerial and equipment and immediately rectify any defect which

be tested as specified above If either of the cylinders in any setshows definite evidence, other than low strength, of impropersampling, molding, handling, curing or testing, it shall be discardedand the strength of the remaining cylinder shall then beconsidered the test result of that set.

(d) Final acceptance of the concrete works is based on 28 days’testing on the three sets of two cylinders each The work isconsidered in compliance if the average of the three sets ofcylinders equals or exceeds the minimum specified for the class ofconcrete being placed and if the average of the two cylinders inany one set does not fall below the specified minimum strength bymore than 35 kg/cm2 If the results of the 28-day testing areunsatisfactory, the Contractor, in accordance with the instructions

of the Engineer, shall conduct tests in the suspect parts of thestructure Should the tests prove that the concrete isunsatisfactory or below the standards specified, the Engineer mayorder the concrete to be removed and replaced with concrete ofthe specified quality or accepted at a reduced payment All theabove shall be at the expense and responsibility of the Contractor

7.1 SLUMPS

(a) Recommended limitations for slump are given in Table No 3above The method of making the slump test shall conform toASTM C 143

(b) One slump test, or more as directed by the Engineer, shall becarried out on every batch of concrete produced, and the test shallnot be deemed to have been carried out unless witnessed by theEngineer or his representative

(c) Mixes of the stiffest consistency that can be placed efficiently shall

be used Over wet mixes will be rejected

(b) The shop drawings shall show the proposed details of constructionsuch as sizes of members, spacing of bents, posts, studs, walers,stringers, collars, bolts, wedges, bracing, rate of pour, and themanufacturer’s recommended safe working capacity of all formties and column clasps All assumptions, dimensions, materialproperties and other data used in making the structural analysisshall be noted on the shop drawings Upon request, the Contractorshall furnish copies of the design calculations to the Engineer forexamination as a condition for approval.

(c) When prefabricated formwork, shoring or scaffolding units areused, the manufacturer’s recommendations for allowable loadsmay be followed if supported by test reports or successfulexperience records For materials which will experience substantialreuse, reduced allowable load values may be required

(d) The design of the formwork shall be the sole responsibility of theContractor and the strutting and bracing of the formwork shall besuch that there shall be no harmful deformation of the forms underthe weight of the plastic concrete, or due to methods adopted forthe placing and compacting thereof, or due to any incidentalloading No accessory for supporting the formwork or stagingsshall be built into the permanent structure except with theEngineer’s approval

(e) Formwork shall be designed for vertical loads and lateral pressures

in accordance with ACI 347 In addition, the formwork shall beconstructed to provide completed concrete surfaces complyingwith the tolerances specified therein

8.2 CONSTRUCTION

(a) The formwork shall be constructed accurately to represent theshape of the concrete as detailed on the Drawings It shall be ofsuitable design and substantial construction and be approved bythe Engineer The Contractor shall make any necessary

(b) No concrete shall be deposited in the forms until all workconnected with constructing the forms and placing all reinforcingsteel, ducts, anchorages, or prestressing steel has been completedfor the unit to be poured and the Engineer has given writtenapproval of said forms, reinforcing steel, ducts, anchorages, orprestressing steel.

(c) Drainage holes and weep holes shall be constructed as detailed onthe Drawings Forms for weep holes shall be as approved by theEngineer

(d) The Contractor shall install in the formwork required inserts,anchors, expansion joint elements, sleeves and other itemsspecified under other Subsections of this Specification and shallcoordinate their installation with other trades in the proper location

of such items Ends of piping and sleeves embedded in concreteshall be closed with caps or plugs

(e) To facilitate finishing, forms used for parapets, barriers, andexposed vertical surfaces shall be removed in not less than 24hours nor more than 48 hours, depending on weather conditions

8.3 GENERAL REQUIREMENTS

(a) The inside surfaces of forms shall, except for permanent formwork,

or unless otherwise agreed by the Engineer, be coated with arelease agent approved by the Engineer Release agents shall beapplied strictly in accordance with the manufacturer’s instructionsand shall not come into contact with the reinforcement orprestressing tendons and anchorages Different release agentsshall not be used in formwork to concrete which will be visible inthe finished Works

(b) Immediately before concreting, all forms shall be thoroughlycleaned out

He must also submit details of the type or types of mixers andmachines to be used, and his proposals for conveying the mixedconcrete from the mixer to the points of deposit.

(b) All concrete shall be batched by weight unless otherwise directed

by the Engineer The weight-batching machines used shall be of atype approved by the Engineer and shall be kept accurate and ingood condition while in use on the Works Checks are to be made

as required by the Engineer to determine that the weighingdevices are registering correctly Each mixer shall be fitted with awater measuring device having an accuracy within one percent ofthe quantity of water required for the batch The measuring deviceshall be such that its accuracy is not affected by variations in thewater supply pressure

(c) In the event aggregate batching is by volume, the cement shall bebatched by weight and the water by weight or volume Each size ofaggregate shall be measured in a metallic container, the depth ofwhich is at least equal to its greatest width The containers shall

be of such shape that their volume can be easily checked bymeasurement

(d) The approved type of mixer shall have a drum rotating about ahorizontal or inclined axis and must be kept in good condition at alltimes The drum shall rotate at the appropriate speed Continuousmixers will not be permitted

(e) The amount of concrete mixed in any one batch shall not exceedthe rated capacity of the mixer The whole of the batch shall beremoved before materials for a fresh batch enter the drum Oncessation of work, including all stoppages exceeding 20 minutes,the mixers and all handling plant shall be washed with clean water.Any deposits of old concrete in the drum shall be cleaned out byrotating clean aggregate and water in the drum before any freshconcrete is mixed

9.2 PLACING AND COMPACTING

(a) Immediately after mixing, the concrete shall be transported to theplace of final deposit by methods that will prevent the separation,loss or contamination of any of the ingredients Any methodinvolving the use of pipes or chutes for transporting concrete willnot be permitted, except with the written approval of the Engineer.(b) Transport of concrete from the mixers shall be as rapid as possibleand the Contractor shall always be responsible for the concretebeing placed and compacted within such a time from the addition

of the water to the mixer that the previous lift of concrete has notcommenced setting

(c) Before any concrete is placed, the formwork shall be thoroughlycleaned of all dirt, shavings, loose stones and other debris

(d) Forms shall be treated with a non-staining material or shall besaturated with water immediately before the concrete is placed.For all exposed surfaces, the forms shall be treated with a non-staining material, as approved by the Engineer, to prevent theadherence to the concrete The forms shall be free from anymaterial that shall adhere to or discolor the concrete

(e) The concrete shall be placed gently in position and shall not have afree fall of more than one meter

(f) Concrete shall be placed so as to prevent water from collecting atthe ends, corners or along the faces of the forms, and water shallnot be placed in large quantities at a given point and allowed torun or be worked over a long distance in the form

(g) All concrete shall be placed and compacted in even layers witheach batch adjoining the previous one

(h) The thickness of concrete layers shall be between 15 and 30 cmfor reinforced concrete and up to 45 cm for unreinforced concrete (i) The concrete shall be carefully and continually compacted andworked around the reinforcement steel and into the corners of theformwork so that the concrete shall be in close contact with thereinforcement steel and free from honeycombing