qcs 2010 part 5.06 property requirements.pdf

8/10/2019 qcs 2010 Part 5.06 Property Requirements.pdf

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QCS 2010 Section 5 Part 6 Property Requirements Page 2

QCS 2010

6. PROPERTY REQUIREMENTS

6.1 GENERAL

6.1.1 Scope

1 This Part includes Grades 15 MPa and above of concrete to be used in the civil works, withthe requirements for workability, permeability, and drying shrinkage.

2 Related Sections and Parts are as follows:

This SectionPart 2, AggregatesPart 3, CementPart 4, WaterPart 5, AdmixturesPart 7, Batching and MixingPart 8, Transportation and Placing of Concrete

Part 9, FormworkPart 13, Inspection and Testing of Hardened Concrete

6.1.2 References

1 The following standards are referred to in this Part. The designer along with contractor areresponsible to use the latest update standard as published by the organization:

ACI 207.1R ......... Guide to Mass ConcreteACI 207.2R ......... Report on Thermal and Volume Change Effects on Cracking of Mass

ConcreteACI 207.5R ......... Roller - Compacted mass concreteACI 213, ............. Guide for Structural Lightweight-Aggregate ConcreteACI 214, ............. Evaluation of Strength Test Results of Concrete

ACI 221, ............. Guide for Use of Normal Weight and Heavyweight Aggregates in ConcreteACI 301, ............. Specifications for Structural ConcreteACI 304, ............. Guide for Measuring, Mixing, Transporting, and Placing ConcreteACI 304.2, .......... Placing Concrete by Pumping MethodsACI 318, ............. Metric Building Code Requirements for Structural Concrete & CommentaryACI 506, ............ Guide to ShotcreteACI 506.1, .......... Guide to Fiber-Reinforced ShotcreteACI 506.2, .......... Specification for ShotcreteACI 555, ............. Removal and Reuse of Hardened Concrete

ASTM A 820, ...... Specification for Steel Fibers for Fiber-Reinforced ConcreteASTM C 1018, .... Test Method for Flexural Toughness and First-Crack Strength of Fiber-

Reinforced Concrete

ASTM C 1116, ... Specification for Fiber-Reinforced ConcreteASTM C 1140, .... Practice for Preparing and Testing Specimens from Shotcrete Test PanelsASTM C 1231, .... Practice for Use of Unbonded Caps in Determination of Compressive

Strength of Hardened Concrete CylindersASTM C 1240, .... Specification for Silica Fume Used in Cementitious MixturesASTM C 138, ...... Test Method for Density (Unit Weight), Yield, and Air Content (Gravimetric)

of ConcreteASTM C 1385, .... Practice for Sampling Materials for ShotcreteASTM C 1480, .... Specification for Packaged, Pre-Blended, Dry, Combined Materials for Use

in Wet or Dry Shotcrete ApplicationASTM C 1550, .... Test Method for Flexural Toughness of Fiber Reinforced Concrete (Using

Centrally Loaded Round Panel)ASTM C 1611, .... Test Method for Slump Flow of Self-Consolidating Concrete


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ASTM C 1666, .... Specification for Alkali Resistant (AR) Glass Fiber for GFRC and Fiber-Reinforced Concrete and Cement

ASTM C 172, ...... Practice for Sampling Freshly Mixed ConcreteASTM C 173, ...... Test Method for Air Content of Freshly Mixed Concrete by the Volumetric

MethodASTM C 231 ....... Test Method for Air Content of Freshly Mixed Concrete by the Pressure

MethodASTM C 311, ..... Test Methods for Sampling and Testing Fly Ash or Natural Pozzolans forUse in Portland-Cement Concrete

ASTM C 387, ...... Specification for Packaged, Dry, Combined Materials for Mortar andConcrete

ASTM C 39, ........ Test Method for Compressive Strength of Cylindrical Concrete SpecimensASTM C 42, ........ Test Method for Obtaining and Testing Drilled Cores and Sawed Beams of

ConcreteASTM C 597, ...... Test Method for Pulse Velocity through ConcreteASTM C 618, ..... Specification for Coal Fly Ash and Raw or Calcined Natural Pozzolan for

Use in ConcreteASTM C 637, ...... Specification for Aggregates for Radiation-Shielding ConcreteASTM C 803, ..... Test Method for Penetration Resistance of Hardened Concrete

ASTM C 805, ..... Test Method for Rebound Number of Hardened ConcreteASTM C 856, ..... Practice for Petrographic Examination of Hardened ConcreteASTM C 900, ..... Test Method for Pullout Strength of Hardened ConcreteASTM C 94, ........ Specification for Ready-Mixed ConcreteASTM C 989, ...... Standard Specification for Slag Cement for Use in Concrete and MortarsASTM C 1399, .... Test Method for Obtaining Average Residual-Strength of Fiber-Reinforced

ConcreteASTM C150, ...... Specification for Portland CementASTM C1604, ..... Test Method for Obtaining and Testing Drilled Cores of ShotcreteASTM C1609, ..... Test Method for Flexural Performance of Fiber-Reinforced Concrete (Using

Beam With Third-Point Loading)ASTM C192, ....... Practice for Making and Curing Concrete Test Specimens in the

Laboratory

ASTM C 232, ..... Test Methods for Bleeding of ConcreteASTM C 31, ........ Practice for making and curing concrete test specimens in the fieldASTM C 33, ....... Specification for Concrete AggregatesASTM C 617, ..... Practice for Capping Cylindrical Concrete SpecimensASTM C 638, ..... Descriptive Nonmenclature of Constituents of Aggregates for Radiation-

Shielding ConcreteASTM C 1152 ..... Standard Test Method for Acid-Soluble Chloride in Morter and Concrete.ASTM C 1218 ..... Standard Test Method for Water-Soluble Chloride in Morter and Concrete.ASTM D 5759, .... Guide for Characterization of Coal Fly Ash and Clean Coal Combustion Fly

Ash for Potential UsesASTM D 6942, .... Test Method for Stability of Cellulose Fibers in Alkaline EnvironmentsASTM E 119, ...... Test Methods for Fire Tests of Building Construction and Materials

BRE digest 433, . Recycled Aggregates

BS 1881, ............ Testing ConcreteBS 4027, ............ Specification for Sulphate-Resisting Portland CementBS 6073-2:2008, Precast concrete masonry units. Guide for specifying precast concrete

masonry unitsBS 812, ............... Testing AggregatesBS 8500, ............ Concrete, Complementary British Standard to BS EN 206-1.BS 8666, ............. Specification for scheduling, dimensioning, bending and cutting of steel

reinforcement for concrete

BS EN 12350,..... Testing Fresh Concrete

BS EN 12350-1, . Testing fresh concrete - Part 1: Sampling


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ISO 1920-10 ....... Testing of concrete -- Part 10: Determination of static modulus of elasticityin compression

RILEM CPC 11.3 Absorption of water by immersion under vacuum

6.1.3 Definitions:

1 Exposure conditions will apply as follows:

(a) Class B: Blinding concrete of minimum strength 15 MPa, and minimum strength 10MPa for concrete Pavement (part 16). For this class, strength is only the requirement.

(b) Class C0: No risk of corrosion or attack - All non-reinforced concrete or Slab onGround.

(c) Class C1:All internal reinforced concrete in dry condition and protected againsthumidity and weather conditions.

(d) Class C1: Low Exposure - All other reinforced concrete in occasionally exposed tohumidity. Concrete surfaces protected against weather or aggressive conditions.

(e) Class C2 Moderate Exposure - Concrete in contact with the ground or below ground,concrete at roof level and all exposed concrete.Concrete sufaces continuously undernon-aggressive water. Concrete in contact with non-aggressive soil and subject tomoisture condensation.

(f) Class C3: Severe Exposure - Concrete in contact with the ground, alternate wettingand drying or severe condensation. Exposed to chloride from airborne

(g) Class C 4: Aggressive Exposure Concrete surfaces exposed to sea water spray orin sea water tidal zone. Occasionally exposed to sea water spray. Exposed tocorrosive fumes. Exposed to abrasive action. Where chloride corrosion is the maineffect of concrete such as in tidal zone, causeways and structural concrete in contactwith water and chloride from airborne, the contractor shall assign a specialist to verifyand predict the life cycle of concrete. And to follow ASTM E-917 for basic standardmeasuring and ACI 365 life-cycle costs of building and building systems

2 "Cementitious Materials": Portland cement in combination with one or more of the following:blended hydraulic cement, fly ash and other pozzolans, ground granulated blast-furnaceslag, silica fume and Metakoalin; subject to compliance with requirements of thisspecification.

3 Water/Cementitious Ratio shall mean the ratio between the total weight of water in theconcrete (less the water absorbed by the aggregate) and the weight of cementitiousmaterials, expressed as a decimal fraction.

4 Admixtures shall mean a material other than water, aggregate, cementitious materials orfiber reinforcement, used as an ingredient of concrete or mortar.

5 Hot Weather shall mean any combination of the following conditions that tends to impairthe quality of freshly mixed or hardened concrete by accelerating the rate of moisture lossand rate of cement hydration, or otherwise causing detrimental results such as: a. Highambient temperature (when the shade temperature is above 40 deg C on a risingthermometer, 43 deg C on a falling thermometer), b. High concrete temperature, c. Lowrelative humidity, d. High wind speed and e. whenever the rate of evaporation exceeds 0.75

Kg/m2/h


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6 Mass concrete is defined as any volume of concrete with dimensions large enough torequire that measures be taken to cope with generation of heat form hydration of the cementand attendant volume change to minimize cracking. Reinforced Massive concrete structuresinclude pile caps, transfer plates, and structural members where the least dimensionexceeds 1.5 meters.

7 Coarse Aggregate shall be considered as that size passing a 28mm sieve (or larger sievesize) and predominately retained on a 5mm sieve.

8 Fine Aggregate shall be considered as that size predominately passing a 5mm sieve andpredominately retained on a 0.063mm size.

9 OPC shall mean ordinary Portland cement or CEM I.

10 PFA shall mean pulverised fuel ash or fly ash.

11 GGBS shall mean ground granulated blast furnace slag.

12 Gap-graded aggregate shall mean graded aggregate without one or more of the

intermediate sizes.

13 Single-size aggregate shall mean aggregates containing a major proportion of particles ofone sieve size.

14 Target Mean Strength shall mean the specified strength plus the margin.

15 Margin shall mean the difference between the specified strength and the target meanstrength.

16 Acceptable or Accepted shall mean acceptable or accepted by the Engineer.

17 Approval or Approved shall mean approval from the Engineer.

18 All-in aggregate shall mean the materials composed of a mixture of coarse and fineaggregates.

6.1.4 Submittals

1 The Contractor shall submit details of mix designs to the Engineer for approval.

2 Material Safety Data Sheet MSDS or equivalent for all products. test results and otherinformation as required to prove compliance with the specification shall be submitted to theEngineer for approval according to the relevant sections of QCS on at least the followingproducts

3 Cement:

(a) Recent independent test results acceptable to the Engineer confirming compliancewith the specified requirements and referenced standards.

(b) Manufacturer's certificates shall also be supplied for each batch of production ofcement or on a weekly basis, whichever is more frequent, certifying compliance withthe relevant standard.

(c) The early compressive strength of each consignment of cement shall conform to therequirements of QCS part 3 at the independent site laboratory. Deviation of more than10% from either the previous consignment value or the rolling average shall be


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immediately reported to the Engineer. Testing at an independent laboratory shall beas instructed by the Engineer.

4 GGBS:

(a) Recent independent test results acceptable to the Engineer confirming compliance

with the specified requirements and referenced standards.

(b) Manufacturer's certificates with all information necessary to verify compliance shallalso be supplied for each consignment of GGBS or on weekly basis, whichever ismore frequent.

(c) The early compressive strength of each consignment of GGBS shall be determined inaccordance with ASTM C989 at the independent site laboratory based on a blend of50/50 % GGBS and CEM 1. Deviation of more than 5% in strength from either theprevious consignment value or the rolling average shall be immediately reported to theEngineer. Testing at an independent laboratory shall be as instructed by the Engineer.

5 PFA:

(a) Recent independent test results acceptable to the Engineer confirming compliancewith specified requirements and referenced standards.

(b) Manufacturer's certificates with all information necessary to verify compliance withinternationally recognized standards shall also be supplied with each consignment ofPFA.

(c) The materials shall comply with QCS part 3. Deviation of the strength factor by morethan 5% from either the previous consignment value or the rolling average shall beimmediately reported to the Engineer and the Technical Manager of the premixcompany.

6 Silica fume:

(a) Recent independent test results acceptable to the Engineer confirming compliancewith specified requirements and referenced standards.

(b) Manufacturer's certificates with all information necessary to verify compliance withinternationally recognized standards shall also be supplied with each consignment ofsilica fume.

(c) 7 day pozzolanic activity test in accordance with ASTM C 1240 on each consignmentof silica fume at the Independent site laboratory. Deviation of the activity index bymore than 5% from either the previous consignment value or the rolling average shall

be immediately reported to the Engineer and the Technical Manager of the premixcompany.

7 Aggregates:

(a) Recent independent test results acceptable to the Engineer confirming compliancewith the specified requirements and referenced standards.

(b) Full details of the proposed sources of aggregates.

8 Water: Recent independent test results acceptable to the Engineer confirming compliancewith the specified requirements and referenced standards.


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9 Admixtures: Manufacturers technical specifications and recommendations. Recent trialresults acceptable to the Engineer illustrating the efficiency of the product for its particularapplication. Tests on specific gravity and solids content shall be conducted at theIndependent site laboratory on each consignment.

10 Mix Designs: Submit concrete mix designs for each type and strength of concrete required at

least sixty (60) days before placing concrete.

11 Mix designs shall be verified by an approved independent testing laboratory in accordancewith requirements of QCS Part 05 and shall be coordinated with design requirements andContract Documents.

12 Submit complete mix design data for each separate mix to be used on the Project in a singlesubmittal with at least the following information:

(a) Type of cement*.

(b) Portland cement content*.

(c) Cementitious content* (GGBS, PFA, natural pozzolan, rice husk ash and/or silicafume).

(d) Max. aggregate size*.

(e) Combined grading curve

(f) Quantities of all individual materials*

(g) Name(s) of admixture(s)*

(h) Target slump/slumpflow (at discharge)*

(i) Details to calculated Water/cementitious material (w/cm) ratio*

(j) Compressive strength grade*

(k) Hardened density

(l) Water absorption (%) and water penetrability (mm)

(m) Coulomb value

(n) Chloride migration coefficient (m2/sec), if required

(o) Bleeding

(p) SO3 and Cl contents

(q) Slump/slump flow variation over time.

(r) Initial and final concrete setting time for each mix design

(s) Target fresh density*

(t) Target temperature*

*Include on delivery report as a minimum


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13 Data shall be from the same production facility that will be used for the Project.

14 Mix Design data shall include but not be limited to the following:

(a) Locations on the Project where each mix design is to be used corresponding toStructural General Notes on the Drawings.

(b) Design Compressive Strength: As indicated on the Drawings.

(c) Proportions: Concrete constituent materials shall be proportioned to yield 1 m3

(d) Gradation and quality of each type of ingredient including fresh (wet) unit weight,aggregates sieve analysis.

(e) Water/cementitious material (w/cm) ratio.

(f) Evaluate and classify fly ash in accordance with ASTM D 5759, C618 or BS EN 450.

(g) Report chemical analysis of fly ash in accordance with ASTM C 311.

(h) Ground Granulated Blast Furnace slag in accordance with BSEN 15167 C989.

(i) Slump

(j) Certification and test results of the total acid and water soluble chloride ion content ofthe design mix.

(k) Air content of freshly mixed concrete by the pressure method (ASTM C231) for normaland heavy weight concrete, or the volumetric method (ASTM C173) for lightweightconcrete

(l) Fresh Density of Concrete: ASTM C 138.

(m) Design strength at 28 days, as indicated on contract documents tested as per BS EN12390.

(n) Submit strength test records, mix design materials, conditions, and proportions forconcrete used for record of tests, standard deviation calculation, and determination of

required average compressive strength.(o) If early concrete strengths are required, contractor shall submit trial mixture results as

required.

(p) Test records to support proposed mixtures shall be no more than 12 months old anduse current cement and aggregate sources. Test records to establish standarddeviation may be older if necessary to have the required number of samples.

(q) Manufacturer's product data for each type of admixture.

(r) Manufacturers certifications that all admixtures used are compatible with each other.

(s) All information indicating compliance with Contract Documents including method ofplacement and method of curing.

(t) Normal weight Concrete: Density per ASTM C 138. Design the mix to produce thestrength, modulus of elasticity and density as indicated on the Contract Documents.

(u) Certification from a qualified testing agency indicating absence of deleteriousexpansion of concrete due to alkali aggregate reactivity in accordance with ASTMC33.

15 Mass Concrete:

(a) Submit mix design for mass concrete elements in conformance with requirements ofACI 301 Section 8. The use of high early strength cement ASTM C 150 Type IIIcement and cement grade with index R is prohibited. The concrete mix design shallnot be designed with a high early strength unless otherwise demonstrated by theContractor for capability of maintaining proper temperature and approved by the

Engineer.


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(b) Submit proposed methods of temperature control, including cementitious materialcontent control in mix design to reduce heat-generating potential of concrete,precooling of ingredients to lower concrete temperature as placed, and methods toprotect mass concrete elements from excessive temperature differentials.

(c) Submit analysis of anticipated thermal development within mass concrete elements

with the proposed mix design for these elements. Results of the analysis, usingmethods in ACI 207.1R and ACI 207.2R such as the Schmidt model and site specificdata, shall address the maximum differential temperature and the maximumtemperature during curing

(d) Submit proposed number and locations of temperature monitoring devices to recordtemperature development between the interior and the exterior of mass concreteelements.

6.2 GRADES OF CONCRETE

6.2.1 General

1 Grades of concrete to be used in the Works shall in general be designed as in para 6.2.2.Where different grades of concrete are required the design of the mix shall follow therequirements of this specification.

2 The concrete grades shall be designed mixes according to classes set in para 6.1.3 andshall comply with the requirements set in the table 6.1:

3 Where adequate workability is difficult to obtain at the maximum water/cementitious ratioallowed, the use of plasticisers or water reducing admixtures may be considered.Alternatively an increase in cementitious content may be considered at the discretion of theEngineer where this will not adversely affect the durability of the concrete.

4 Cement contents in excess of 400 kg/m

3

shall not be used unless special consideration hasbeen given to the effect for heat of hydration and reduce thermal stress in the concrete, andapproval has been obtained from the Engineer. The maximum cementitious content shall notexceed 500kg/m

5 The proportioning, mixing and placing of the mixture shall be in accordance with Parts7 and8 of this Section

6 Temperature (at placement):

(a) Maximum fresh concrete temperature shall not exceed 32C unless constructiontesting to verify a proposed concrete mixture will function satisfactorily at a concretetemperature greater than 32C. No concrete shall be placed if the concrete

temperature is above 35o

C

(b) Methods to reduce fresh concrete temperature shall minimize energy consumption inaccordance with the sustainability goals of the project.

(c) The concrete producer shall demonstrate that temperature of concrete due tohydration particularly in mass concrete structures shall comply with this specificationpara 6.2.3.3 with the proposed maximum fresh concrete temperature. The suppliermay use in his demonstration testing heat sensors and simulation technologies whichmeasure the concrete heat of hydration and its rate versus concrete curing age.


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7 The Contractor is responsible for ensuring that the concrete is able to be fully compactedwithin the concrete element regardless of reinforcing density or other limitations. This mayinvolve reducing the maximum aggregate size, increase the level of concrete workability oruse self compacting concrete. Generally the slump of concrete as delivered to site shall be inthe range of 120mm to 200mm depending on the type/area of application unless otherwisespecified by the Engineer.

Table 6:1a Minimum concrete cube strength grade based on concrete exposure conditions:

Exposure ConditionsClasses

Concrete cube Strength GradesB10 B15 B20 C25 C30 C35 C3

7C40 C45 C50 C75

1 Class B: Blinding concrete

2 Class 0: No risk ofcorrosion or attack - Allnon-reinforced concreteor Slab on Ground.

3 Class 1: All internal

reinforced concrete in drycondition and protectedagainst humidity andweather conditions.

4 Class 1: Low Exposure -

All other reinforcedconcrete in occasionallyexposed to humidity.Concrete surfacesprotected against weatheror aggressive conditions.

5 Class 2: ModerateExposure - Concrete in

contact with the ground orbelow ground, concrete atroof level and all exposedconcrete,.Concretesufaces continuouslyunder non-aggressivewater. Concrete in contactwith non-aggressive soiland subject to moisturecondensation.

6 Class 3: Severe Exposure- Concrete in contact withthe ground, alternate

wetting and drying orsevere condensation.Exposed to chloride fromairborne

7 Class 4: AggressiveExposure Concretesurfaces exposed to seawater spray or in seawater tidal zone.Occasionally exposed tosea water spray. Exposedto corrosive fumes.Exposed to abrasive

action.


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Table 6.1b: Concrete mixtures grades requirements:

1. The strength requirement is based on the design criteria; conversation of cylinder/cube shall be asspecified in above table or as indicated in QCS Part 05-06 clause 6.4.2.9.b.4.

2. For Prestressed concrete the chloride limits are 0.08 and 0.06 respectively

3. Applicable where concrete is exposed to soils and water and not protected by waterproofingmembrane.

4. Test method according to ASTM C1152 or BS 1881: Part 124.

5. Test method according to ASTM C1218 .

ConcreteGrade

Minimum CubeCompressive

strength @ 28days fc-cube

MinimumCylinder

Compressivestrength @ 28days fc-cyl

1

Minimum

cementitiouscontent

Maximum

Water :CementitiousRatio

Maximum Chloridelimit for new

construction, % by

mass ofcementitious

material2

Maximum expansion

when tested usingASTM C10123

(N/mm2) (N/mm

2) (Kg/m

3) (W/C)

Acid

soluble4

Water

soluble5

(months)

6 12 18

B 10 10 8 - - N.A N.A N.A N.A N.A

B 15 15 12 - - N.A N.A N.A N.A N.A

B 20 20 16 - - N.A N.A N.A N.A N.A

C 25 25 20 260 0.55 N.A N.A N.A N.A N.A

C 30 30 25 300 0.50 0.20% 0.15% N.A N.A N.A

C 35 35 - 320 0.47 0.20% 0.15% 0.10% N.A N.A

C37 37 30 325 0.46 0.10% 0.08% 0.10% N.A N.A

C 40 40 - 335 0.45 0.10% 0.08% 0.10% N.A N.A

C45 45 35 355 0.42 0.10% 0.08% 0.05% 0.10% N.A

C 50 50 40 370 0.40 0.10% 0.08% N.A N.A 0.10%

C 75 75 60 390 0.35 0.10% 0.08% N.A N.A 0.10%


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Table 6.1c: Concrete Durability Requirements and Tests

No. Durability Requirements

Durability level1

minimumLevel ModerateLevel

ModeratelyHigh Level High Level

1 concrete exposure condition Class 1Class 2Class 1

Class 3Class 2Class 1

Class 4Class 3Class 2Class 1

2Minimum cube compressivestrength grade

C35 C40 C50 C75

Durability Test1 Maximum Durability Requirement @ 28 days concrete age

2

3Water Penetration, BS EN

12390-8 (mm)

25 15 10 5

4Resistance to Chloride ionPenetration (RCP), ASTM C1202 (coulombs)

4000 2000 1000 500

5Chloride Migration

3, NT Build

492 (m2/s)

N.A 5.0 x 10-12

3.0 x 10-12

1.0 x 10-12

6Water Absorption, BS 1881:Part 122 (%)

2.5 2.0 1.61.2

1. The durability level and requirement test or tests shall be applied when requested by the Engineer andshall be tested at 28 days.

2. Exception will be made for mass concrete structure, or concrete mix containing fly ash, silica fume, orGGBS , concrete strength grade C50 or more and for Exposure Conditions class 3 or class 4 thedurability requirement shall be requested at 56 days ,or 91 days if approved by the Engineer.

3. Optional requirement.

6.2.2 Design of Concrete Mixes

1 At the start of the construction period, the Contractor shall design a mix for each grade ofconcrete as stated hereafter.

2 Each mix design shall be such that:

(a) the aggregate shall comprise fine aggregate and coarse aggregate with size specifiedin part 2

(b) the combined aggregate grading shall be continuous(c) the aggregate quantity shall be calculated by weight SSD.

3 Where a concrete production facility has strength test records not more than 12 months old,

a sample standard deviation, Ss, shall be established. Test records from which Ss iscalculated shall consist of at least 30 consecutive tests or two groups of consecutive teststotalling at least 30 tests

4 Where a concrete production facility does not have strength test records meetingrequirements of 6.2.2(3) above, but does have test records not more than 12 months old


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based on 15 to 29 consecutive tests, a sample standard deviation Ssshall be established asthe product of the calculated sample standard deviation and modification factor of Table 6.2

Table 6.2Modification Factor for Sample Standard Deviation When Less Than 30 Tests Are Available

No. of tests Modification factor for samplestandard deviation

Less than 15 Use para 7. Below

15 1.16

20 1.08

25 1.03

30 1.00

1- Interpolate for intermediate number of tests

2- Modified sample standard deviation, Ss, to be used to determined

required average strength fcr

5 To determine the correction factor between cube strength and cylinder strength, thecontractor shall establish at least 30 consecutive strength tests from each proposed mixdesign. This correction will remain valid thru the project providing that no change in theproperties of the materials and no change in source occurred.

6 Required average compressive strength (Target Mean Strength) fcr used as thebasis for selection of concrete proportions shall be determined from Table 6.3using the sample standard deviation, Ss

Table 6.3: Required Average Compressive Strength (Target Mean Strength) When Data Are AvailableTo Establish A Sample Standard Deviation

Specified compressive strength,N/mm2 or MPa

Required average compressive strength,Target Mean Strength, N/mm2 or MPa

Fc < 35 MPa --- see footnote Fcr = fc + 1.34Ss------------------ Eq. 1

Fcr = fc + 2.33Ss 3.5 ---------- Eq. 2

Fc > 35 MPa --- see footnote Fcr = fc + 1.34Ss------------------ Eq. 1

Fcr = 0.90fc + 2.33Ss------------ Eq. 3

Note: Use the larger value computed from any equation

7 When a concrete production facility does not have field strength test records forcalculation of Ss, Required average strength (Target Mean Strength) fcr shall bedetermined as follow:

(a) Fcr = fc + 8.5 MPa when 20 < fc < 35 MPa(b) Fcr = 1.10fc + 5 MPa when fc > 35 MPa


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6.2.3 Portland Cement Concrete

1 Portland cement concrete shall consist of a mixture of Portland cement, cementitious, fineaggregate, coarse aggregate, water, and additives (when required). It shall be classified as intable 6.2.1 unless otherwise stated hereafter and requested by the Engineer.

2 Blinding concrete

(a) Blinding concrete shall be of minimum Grade 15 and above.

(b) The thickness of the blinding concrete shall be as shown on the Drawings, but shall inno instance be less than 75mm.

(c) The surface finish to blinding concrete shall be Class U2 as specified in Clause 9.3.1of Part 9 of this Section or as directed by the Engineer.

3 Mass Concrete

(a) The fresh concrete temperature at placing shall not exceed 21oC unless otherwise a

higher temperature can be demonstrate the satisfactory of concrete with crack freefrom thermal effect, Delayed Ettringite formation and/or internal sulphate attack. Themaximum allowable differential temperature between the interior and the exterior ofthe mass concrete element shall not exceed 25 deg C. The maximum temperature inany location within the mass concrete structure during curing shall not exceed 70 degC. The drop in concrete surface temperature during, and at the conclusion of thespecified curing period, shall not exceed 11 deg C in any 24 hour period. The internaldifferential temperature of concrete shall not exceed 20

oC for gabbro aggregates and

30oC for limestone aggregates.

4 Self Consolidating Concrete

(a) General: Self Consolidating Concrete (SCC) is an innovative concrete that does notrequire vibration for placing and compaction. It is able to flow under its own weight,completely filling formwork and achieving full compaction, even in the presence ofcongested reinforcement. The hardened concrete is dense, homogeneous and hasthe same engineering properties and durability as traditional vibrated, fully compactedconcrete.

(b) Self Consolidating Concrete Supplier: SCC shall be supplied by a competent concreteproducer with a record of successfully producing this type of concrete at considerablevolume and with high consistency.

(c) Constituent Materials, General: The constituent materials for SCC are the same asthose used in traditional vibrated concrete conforming to EN 206-1, as specified in

part 2 of this section.

(d) To achieve these requirements the control of the constituent materials needs to beincreased and the tolerable variations restricted, so that daily production of SCC iswithin the conformity criteria without the need to test and/or adjust every batch.


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(e) Test Requirements for SCC:

Laboratory tests Field Tests

Slump-flow by Abrams cone 600 750 mm 550 750 mm

T500mm slump flow by Abramscone

3 6 sec 3 10 sec

V-Funnel 6 25 sec N.A

5 minute V-Funnel < 3 sec N.A

L-Box (3 bars) > 0.80 N.A

J-Ring < 10mm N.A

(f) Concrete specimens shall be moulded in single layer without rodding and tapping

(g) Slump flow and VSI testing shall be performed as outlined in ASTM C 1611/C 1611M

5 Pile Concrete

(a) The cementitious content shall not be less than 370 kg/m3

(b) The water-cememtitous ratio shall not exceed 0.45

(c) The concrete mixture shall be designed of high slump not less than 150 mm allowingproper free fall with excellent homogeneity. When concrete mixture requires slump ofgreater than 230 mm, it shall be designed as Self Consolidated Concrete. Theincrease in slump shall be made using proper admixtures. The use of chemical

admixture including air-entraining or any other shall be evaluated as it increases theworkability, if needed and approved by the engineer.

(d) The concrete slump shall have adequate retention using approved type of retarderand shall be submitted in the design mix.

(e) The increase in workability shall not permit any decrease in the specified designstrength

(f) The concrete in a pile shall, if at all possible, be placed in one continuous operation.

6 Underwater concrete shall generally comply with ACI 304 Chp 8 and following

characteristics:

(a) The Cementitious content shall not be less than 390 kg/m3

(b) The water-cementitious ratio must not exceed 0.40

(c) Fine aggregate contents of 45 to 55% by volume of total aggregate and air contents ofup to approximately 5% are generally specified.

(d) Concrete shall be more cohesive and less prone to washout of cement or fines fromthe concrete during placement. Antiwashout admixtures or alternative concrete mixshall be used for underwater concrete.


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(e) Trial placements shall be conducted to verify that the concrete proportioned with theantiwashout admixture can maintain adequate slump life and can flow for the requireddistance.

(g) The concrete mixture shall be designed of high slump not less than 150 mm allowingproper free fall with excellent homogeneity. The use of air-entraining admixture shall

be evaluated as it increases the workability. When concrete mixture requires slump ofgreater than 230 mm, it shall be designed as Self Consolidated Concrete. Theincrease in slump shall be made using proper admixtures.

(h) The concrete slump shall have adequate retention using approved type of retarderand shall be submitted in the design mix.

(i) The increase in workability shall not permit any decrease in the specified designstrength

(f) The concrete shall be placed in one continuous operation

(g) The final selection of a concrete mixture shall be based on test placements made

under water in a placement box or in a pit that can be dewatered after the placement.Test placements shall be examined for concrete surface flatness, amount of laitancepresent, quality of concrete at the extreme flow distance of the test, and flow aroundembedded items, if appropriate.

7 Shotcrete

(a) The classification of shotcreting shall be in accordance to the process used (wet-mixor dry-mix) and the size of aggregates used.

(b) All materials shall be as per QCS except for aggregate where gradation shall be asper ACI 506R and 506.2R

(c) Steel and synthetic fibers will be used to reduce propagation of cracks. Fibers shall beas per Manufacturer supplier data sheet and shall conform to ASTM A 820 for steelfibers and ASTM C1116 for synthetic fibers.

(d) The nozzle operator should be certified (refer to ACI CP-60) and have completed atleast one similar application as a nozzle operator on a similar project. The nozzleoperator should also be able to demonstrate, by test, an ability to satisfactorily performthe required duties and to apply shotcrete as required by specifications

(e) Before shotcreting the surface shall be prepared and maintained before and duringshotcrete application. Surface preparation shall conform to ACI 506 R chap. 5

(f) The cementitious content shall not be less than 360 Kg/m3 where wet-mix is appliedthe slump shall be in the range of 40 to 80 mm

(g) Normal testing ages for compressive strength are 7 and 28 days; however, shorterperiods may be required for particular applications or conditions as directed by the

Engineer. Testing shall be on daily production or every 40 m3whichever is greater.

(h) Sampling and testing, however, should be varied according to the size and complexityof the project. Sampling should be done in accordance with ASTM C 1385. Makingextra cylinders or panels shall be at the request of Engineer if testing results vary.

(i) Testing for water absorption, drying shrinkage, and resistance to freezing-and-thawingcycles shall be at the request of the Engineer.


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(j) Fiber-reinforced shotcrete requires fiber washout tests or flexural toughness testingaccording to ASTM C 1018.

(k) Acceptance of shotcrete should be based on results obtained from drilled cores orsawed cubes (ASTM C 42). The use of data from nondestructive testing devices, suchas impact hammers or probes (ASTM C 805, ASTM C 803), ultrasonic equipment

(ASTM C 597), and pull-out devices (ASTM C 900) may be useful in determining theuniformity and quality of the in-place shotcrete. These tests, however, may not providereliable values for compressive strength.

(l) Core grading is a method used to evaluate encasement of reinforcement. Coregrading shall be used for nozzle operator evaluation. Core grading should not be usedto evaluate structures.

8 No-Fines Concrete and Pervious concrete

(a) No-fines concrete shall be made using a coarse aggregate conforming QCS section 5part 3

(b) Proportion of aggregate, cement and water shall be determined by trial mixes by theContractor and to be accepted by the Engineer.

(c) All the aggregate particles are to be coated with a film of cement grout.

(d) No-fines concrete when placed shall contain no layers of laitance.

(e) No-fines concrete shall not be mixed by hand.

(f) Vibration shall not be used to compact no-fines concrete.

(g) Three test cubes of no-fines concrete shall be made of each preliminary mix.

(h) Minimum crushing strength of the chosen mix shall be 5 MPa at 28 days.

(i) The porosity of no-fines concrete shall be such that water will pass through a slab

300mm thick at the rate of not less than 7l/m2 s of slab with a constant 100mm

depth of water on the slab.

(j) Where a slab incorporating vertical weep holes or drain holes is casted above a layerof no-fines concrete; any polyethylene sheeting shall be pierced below the pipesforming such drain holes and the edges of the sheeting sealed to the lower end of thepipe to prevent the ingress of grout and fine particles from the slab concrete into theno-fines concrete.

(k) The limit for the maximum height of drop while placing is not applicable for no finesconcrete.

(l) Formwork shall remain in place until the no fines concrete has gained adequatestrength to support itself as per the requirements of Part 10 of this Section.

(m) Curing shall be carried out in accordance with the provisions of Part 11 of this Section

(n) The fresh density of Pervious concrete shall be tested as per ASTM C1688 and theinfiltration rate shall be tested as per ASTM C1701 and to follow ACI 522.1R fortesting and quality control scheme.

9 Concrete with recycled aggregates shall be generally approved once the source of recycled

aggregates is identified based on type and approved by the Engineer.


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(a) The recycled aggregates shall be subject for examination as per ASTM C856.

(b) The recycled aggregates shall meet with BS EN 12620 and QCS requirements.

(c) Recycled aggregates shall always be moist above saturation stage at batching plant

(d) The concrete made with recycled aggregates shall be limited to design strength of 20MPa cube strength; unless otherwise accepted by the Engineer. EN 206, ACI 555 andBRE digest 433 shall be the code of practice and guide for the usage of recycledconcrete aggregates in concrete.

(e) Concrete made with recycled aggregates shall be tested for shrinkage, modulus ofrupture, carbonation, chloride penetration which they shall meet with design criteria ofthe project.

(f) The Water-cementitious ratio shall not exceed 0.45

(g) To determine a target mean strength on the basis of a required strength, a higherstandard deviation (increased by 40%) shall be used when designing a concrete with

recycled aggregates of variable quality than when recycled aggregate of uniformquality or virgin aggregates are used

(h) Specific gravity, unit weight, and absorption of aggregates should be determinedbefore mixture proportion studies

(i) The mixture proportion should be based on the measured density of the recycledaggregates intended in the job concrete

(j) Trial mixes shall be made to verify the requirements with project specification andQCS.

10 Heavyweight and radiation shielding concrete

(a) The quality of the aggregates should comply with the requirements of QCS for normalweight aggregates, ASTM C 637 for heavyweight aggregates and ASTM C638 foraggregates to be used in radiation-shielding concrete.

(b) When ferrophosphorous aggregates are used, tests shall be made to determine ifgases (nontoxic) might be released during construction.

(c) Aggregates shall be checked for every delivery to ensure that they conformcompletely with purchase specifications

(d) Aggregates shall be frequently evaluated for the effects of deleterious substances or

aggregate coatings on concrete strength or the promotion of corrosion in metallicaggregates or embedments

(e) The chemical properties of all high-density aggregates must be provided to theEngineer for evaluation before use with due consideration given to chemical reactivity,particularly in highly alkaline environment as found in cement paste.

(f) Tests for alkali-aggregate reactivity shall be determined from each source andsupplier and shall be made every 3 months.

(g) The fresh density of high-density concrete shall be made from each truck

(h) Lead shot concrete shall not be use for structural concrete.


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No fraction of a container delivered unsealed, or left over from previous work, shall beused unless weighed.

(f) Prepackaged, dry, combined materials, including fibers, shall comply with thepackaging and marking requirements of Specification ASTM C 387 or C 1480 andshall be accepted for use provided that after addition of water, the resulting fiber

reinforced concrete meets the performance requirements of this specification

(g) Batching plant used for the preparation of continuously mixed fiber-reinforcedconcrete shall comply with the applicable requirements of NRMCA. Fiber-reinforcedconcrete shall be added directly to the concrete at the time of batching in amounts inaccord with approved submittals for each type of concrete required. Mix concrete instrict accord with fiber-reinforced concrete manufacturer, instructions andrecommendations

(h) Fiber-reinforced concrete shall be free of fiber balls when delivered

(i) The manufacturer of the fiber-reinforced concrete shall furnish to the purchaser adelivery ticket or statement of particulars on which is printed, stamped, or written,

information with details of the type, brand, and amount of fibers used.

(j) The contractor shall afford the inspector all reasonable access, without charge, for theprocurement of samples of freshly mixed fiber-reinforced concrete at the time ofplacement to determine compliance with the requirements of this specification.

(k) Samples of batch-mixed fiber-reinforced concrete shall be obtained in accordancewith Practice ASTM C 172 or C 1385/C 1385M for shotcrete as appropriate, exceptthat wet-sieving shall not be permitted. Sampling for uniformity tests shall be inaccordance with specification ASTM C 94/C 94M

(l) If the measured slumps, time of flow, or air content fall outside the limits permitted bythis specification, make a check test immediately on another portion of the same

sample. If the results again fall outside the permitted limits, the material representedby the sample fails to meet the requirements of this specification

(m) The following shall apply to all forms of fiber-reinforced concrete except dry-mixshotcrete. When applicable, the slump shall be in tolerance with this section para6.4.2.5 (a) and (b).

(n) The time of flow shall be in the tolerances as follow:

(i) When the project specifications for time of flow are written as a minimum ornot less than requirement

Specified time of flow

If 15sec or less If more than 15 sec

Plus Tolerance 5s 10s

Minus Tolerance 0s 0s

(ii) When the project specifications for time of flow are not written as a minimumor not less than requirement:

Tolerances for time of flow

For specified time of flow Tolerance

8 to 15 s + 3s

More than 15 s + 5s


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(o) Finishability - Pre-project trials shall be utilized to determine acceptable surfacefinishability by the Engineer. The manufacturer shall provide the services of a qualifiedtechnician to instruct the concrete supplier in proper batching and mixing of materialsto be provided.

(p) Provide fibers for concrete reinforcing capable of achieving a two hour fire resistance

rating when tested under ASTM E 119. Fire tests must be certified.

12 Lightweight concrete

(a) This clause of the specification refers to lightweight concrete with improved insulationproperties where the practical range of densities is between about 300 and 1850kg/m3.

(b) The required density and strength of the lightweight concrete will be specified on thedrawings or directed by the Engineer.

(c) The method of production of lightweight concrete will be shown on the drawings ordirected by the Engineer. The Contractor shall submit full technical details of thematerials and method of production for the lightweight concrete along with a list ofprevious projects where the particular system has been used.

(d) After source approval of the material and system the Contractor shall submit a mixdesign for the lightweight concrete for the approval of the Engineer. After the reviewand approval of the mix theoretical mix design the Contractor shall carry out a trial mixto check the workability of the fresh concrete and to allow samples to be made forcompressive strength and density.

(e) The Engineer may also instruct that tests are carried out for abrasion resistance andthermal insulation properties.

(f) Iightweight concrete shall be made with lightweight aggregates as approved in part 2of section 05 in QCS for its use in concrete

(g) The performance of lightweight concrete shall follow ACI 213R

6.3 TRIAL MIXES

1 As soon as the Engineer has approved the concrete mix design for each grade of concreteand during or following the carrying out of the preliminary tests, the Contractor shall prepare

a trial mix of each grade in the presence of the Engineer at least 35days before

commencement of concreting. Trial mix shall be mixed and handled by means of the sameplant which the Contractor proposes to use in the Works. The trial mix shall comprise notless than 50% from the central mixing drum capacity but not less than 0.5 m3 of concrete.The trial mix can be exempted if concrete supplier provides thru an independent approvedtesting agency adequate history on strength:

(a) Not less than 50 strength test results as in para 6.2.2 of this specification

(b) The results shall valid by no more than 6 months from the date of approval

2 Batch the field concrete trial mixture within -2C of the proposed maximum allowable freshconcrete temperature in a truck-mixer with a minimum batch size of 3 m

3.


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3 The concrete mixture shall be held in the mixer for 90 minutes, unless otherwise specified bythe Engineer. During the entire 90-minute period, agitate the mixer at 1 to 6 rpm. At the endof 90 minutes, mix the concrete mixture at full mixing speed designated by the manufacturer(6 to 18 rpm) for 2 minutes.

4 For each trial mix, a plant production trial shall be carried out and the slump of the concrete

checked immediately after discharge from the mixer and thereafter at 30 min intervals up tothe maximum time period envisaged for delivery and standing on site. Based on this trial themix design shall identify any adjustments to the range of plasticiser for acceptableworkability for different times after batching. Where ready mix concrete is being used, theabove requirement may be waived at the discretion of the Engineer if the Contractor hasdocumented previous experience of a particular mix design with test results available.

5 The proportions of cement, aggregate and water shall be carefully determined by weight inaccordance with the Contractor's approved mix design (or modified mix design afterpreliminary tests).

6 Each sample shall consist of at least 9 specimens for strength analysis where 3 specimensfor each age will be tested to determine the concrete strength at the required age.

7 If either or both the average value of the strength of the three cubes tested at 28d is lessthan the required strength (target strength) or the difference between the greatest and the

least strengths is more than 20% of the average strengths, the Contractor shall takemeasures as deemed necessary such as:

(a) Propose new mix design(b) Provide new materials and prepare and test further trial mixes until specified

requirements are achieved.

8 Additionally, the Contractor shall measure the temperature, workability of concrete in eachbatch.

9 When requested by engineer, a mock-up of 2x2x2 m3 shall be made at jobsite and full scaletests of the workability of each trial mix of each grade of concrete shall be made by theContractor in the presence of the Engineer. The trial mix of each grade of concrete shall bebatched, mixed and then transported a representative distance in the manner that theContractor proposes to batch, mix and transport the concrete to be placed in the Works.After discarding the first batch so made, the concrete shall be placed and compacted in trialmoulds both for reinforced and mass concrete with dimensions typical of the Works. Thesides of the moulds shall be capable of being stripped without undue disturbance of theconcrete placed therein. The sides of the moulds shall be stripped after the concrete has setand the workability judged on the compaction obtained. If the workability test shows that theworkability required is not attained for any trial mix for any class of concrete, the trial mixshall be redesigned by the Contractor and a further full scale workability test shall beundertaken for that trial mix of concrete.

10 Redesign of the concrete mixes and trial mixes of concrete shall be repeated for each gradeof concrete until the concrete meets the requirements in this specification and it is verified byfull scale mockup test as described above.

11 The Contractor shall use only the approved mix of each grade of concrete in the Works. If atany time during the construction of the Works the source of cement or aggregate is changedor the grading of the aggregate alters to such an extent that the fraction of aggregateretained on any sieve cannot be maintained within two percent of the total quantity of fineand coarse aggregate when adjusted in accordance with this Clause, then further trial mixesof concrete shall be made, tested and approved for use.


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fresh concrete are to be approved by the Engineer depending on location and exposure andit shall be recorded on the batch ticket for each delivery.

5 Any variations from approved slumps necessitated by the use of superplactisers or otheradmixtures or additives shall be approved by the Engineer. Unless other tolerances areincluded in the project specification, the following shall apply:

(a) When the project specifications for slump are written as a maximum or not toexceed requirement:

Specified Slump

If 75 mm or less If more than 75 mm

Plus tolerance 0 0

Minus tolerance* 40 mm 60 mm

(b) When the project specifications for slump are not written as maximum or not toexceed requirement:

Tolerances for nominal slumps

For specified slump of: Tolerance

50 mm and less 20 mm

50 mm to 100 mm 30 mm

More than 100 mm 40 mm

6 The adjustment for the slump of concrete to fit the job requirement can be conducted onlyone time using a proper additive at jobsite provided that such addition does not increase thewater-cement ratio and setting time above the maximum permitted by the specifications.This addition will only be made at the approval of Engineer.

7 Concrete shall be available within the permissible range of slump for a period of 30 minstarting either on arrival at the job site or after the initial slump adjustment as permittedabove, whichever is later. The first and last quarter m

3 discharged are exempt from this

requirement. If the user is unprepared for discharge of the concrete from the vehicle, theproducer shall not be responsible for the limitation of minimum slump after 30 min haveelapsed starting either on arrival of the vehicle at the prescribed destination or at the

requested delivery time, whichever is later.

8 When air-entrained concrete is desired the purchaser shall specify the total air content of theconcrete. The air content of air-entrained concrete when sampled from the transportationunit at the point of discharge shall be within a tolerance of +1.0% of the specified value.

9 Concrete strength test:

(a) Each concrete strength sample shall consist of at least seven specimens, two to betested at 7 days, three at 28 days and two to be tested at the discretion of theEngineer. Additional samples may be prepared as directed by the Engineer to betested at the discretion of the Engineer for strength and/or durability.


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(b) When concrete cylinders have been specified, the concrete specimens shall not becapped using sulphur for environmental effect. The Contractor shall follow one of thefollowing procedures and as approved by the Engineer:

(i) Cap the specimens in accordance with ASTM C617 using neat cement pasteand/or High-strength gypsum cement paste

(ii) Saw cut and Grind the surface of the concrete to the desired planeness andperpendicular

(iii) Test the concrete cylinders using Unbonded Caps in accordance with ASTMC1231

(iv) For field specimens, the contractor has the right to either use the conversationlisted in EN 206 or determine the conversion factor for each specified concretemix design by testing at least 36 comparative specimens (i.e. 18 cubes versus18 cylinders sampled from 3 consecutive batch trial mix).

(c) A minimum of one sample shall be taken of each mix every day the mix is used

(d) Samples shall be taken at the average rate of one sample every 30 m3of concrete or

fractions thereof for the first 90 m3, then one sample every 100 m

3 of concrete or

fraction thereof when continuous concrete production reaches up to 2000 m3and later

of one sample every 200 m3of concrete or fraction thereof when concrete production

exceeds 2000 m3.

(e) If the average strength of the three specimens at 7d indicate that the required

strength at 28d will not be achieved the Contractor shall immediately:

(i) stop all concreting until checks are made on material and equipment

(ii) rectify any defect which has become apparent as the result of checking.

(f) At Contractors option, defective concrete may be removed and replaced withoutwaiting the 28 d test results.

(g) A test shall be the average of the strength of the specimens tested at the agespecified. If a specimen shows definite evidence other than low strength, of impropersampling, molding, handling, curing, or testing, it shall be discarded and the strengthof the remaining cylinder shall then be considered the test result. To conform to therequirements of this specification, strength tests representing each class of concretemust meet the following requirements:

(i) The average of any three consecutive strength tests shall be equal to, or

greater than, the specified strength, f c, and

(ii) When the specified strength is 35 MPa or less, no individual strength test(average of at least two specimen tests) shall be more than 3.5 MPa below thespecified strength, f c

(iii) When the specified strength is greater than 35 MPa, no individual strength test(average of two specimen tests) shall be less than 0.90f c.

(h) If works test specimens fail at 28 days the Contractor shall suspend concretingoperations and shall not proceed further without approval. The Contractor shall carryout in-situ testing of the suspect concrete in accordance with Part 13 of this Section, inthe presence of the Engineer. All defective work shall be replaced and retested to the

satisfaction of the Engineer.


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6.4.3 Hardened Tests for Fiber-Reinforced Concrete

(a) When post-crack flexural performance is used as the basis for acceptance of fiber-reinforced concrete, make, condition, and test sets of test specimens in accordancewith Test Method ASTM C1399, C1550 or C1609/C1609M as specified.

(b) When flexural strength is used as the basis for acceptance, make and test sets of atleast three test specimens in accordance with the requirements for sampling andconditioning given in Test Method ASTM C1609/C1609M. Test specimensrepresenting thin sections, as defined in C1609/C1609M, or specimens representingfiber-reinforced shotcrete of any thickness, shall be tested as cast or placed withoutbeing turned on their sides before placement on the support system. Acceptance shallnot be based on flexural strength alone when post-crack performance is important.Test Method C1609/C1609M provides for the determination of first peak flexuralstrength when required by the purchaser. For many type-amount fiber combinations,the first peak flexural strength is not significantly greater than the peak strength inflexure.

(c) When compressive strength is used as part of the basis for acceptance of fiber-

reinforced concrete, make sets of at least two test specimens in accordance with theapplicable requirements of Practices ASTM C31/C31M and C192/C192M and asspecified in this section, or Test Methods C42/C42M or C1604/C1604M and conditionand test in accordance with Test Methods BS EN 12390, C39/C39M, C42/ C42M, orC1604/C1604M. Acceptance shall not be based on compressive strength alone.

(d) The frequency of tests on hardened fiber-reinforced concrete shall be in accordancewith the following requirements:

(i) Batch-Mixing: Tests shall be made with same frequency as in conventionalconcrete stated in 6.4.2.9. Each test shall be made from a separate batch. Oneach day fiber-reinforced concrete is mixed, at least one test shall be made foreach class of material.

(ii) When fibers are added, subject for approval of the Engineer, at the truck mixerthe tests shall be made for each 20 m

3 or fraction thereof, or whenever

significant changes have been made in the proportioning controls. On each dayfiber-reinforced concrete is mixed, at least one test shall be made for each classof material.

(iii) For Shotcrete: Tests shall be made for each 38 m3 placed using specimens

sawed or cored from the structure or from corresponding test panels preparedin accordance with Practice ASTM C1604 and C 1140. On each day fiber-reinforced shotcrete is prepared; at least one test shall be made for each classof material.

6.4.4 Quality Contro l charts

1 The Contractor shall submit a continuous statistical analysis, on a monthly bases, forstrength showing the potential strength of the concrete, variations in measured strength bydetermining the standard deviation (margin), batch-to-batch variations of the proportions andcharacteristics of the constituent materials in the concrete, the production, delivery, andhandling process, and climatic conditions; and variations in the sampling, specimenpreparation, curing, and testing procedures (within-test).

2 The Contractor shall provide in his analysis the mean strength, calculated standarddeviation, the normal distribution of concrete strength and the frequency histogram. TheContractor shall draw the upper and lower lines for warning line (Target mean strength + 2 x

standard deviation) and control line (Target mean strength + 3 x standard deviation)


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3 The contractor shall use the methods, of computing standard deviation along with coefficientof variation and factors for computing within-test standard deviation from range, addressedin ACI 214

4 This recalculated margin, if adopted by the Engineer, becomes the current margin for thejudgement of compliance with the specified characteristic strength of concrete

5 When standard deviation or coefficient of variation are relatively high that represent lowquality, the Engineer has the right to stop concreting until the Contractor provide correctiveand preventive measures.

For classes C0, C1, C1 and when strength is equal or less than 35 MPa

Overall variation

Class of operation

Standard deviation for different control standards, MPa

Recommended Acceptable Low

General construction testing Below 3.4 MPa 3.4 to 4.8 MPa Above 4.8 MPa

Within-test variation

Class of operation

Coefficient of variation for different control standards, %


Field control testing 4.0 4.0 to 6.0 Above 6.0

For classes C2, C3, C4 and when strength is higher than 35 MPa

Overall variation

Class of operation Coefficient of variation for different control standards, %


General construction testing Below 9.0 9.0 to 14.0 Above 14.0

Within-test variation

Class of operation Coefficient of variation for different control standards, %


Field control testing 4.0 4.0 to 6.0 Above 6.0

6.5 WORKS TEST CUBES

1 Test cubes shall be taken as specified from fresh mixed concrete which is being used in theWorks and which has been prepared in the normal way.

2 Cubes shall be numbered consequently and marked:


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(a) Time, date and name of individual

(b) Section of work from which samples are taken

(c) Mix reference and delivery note number

(d) Name of technician

(e) and any other relevant information.3 Tests for slump and temperature shall be made and recorded whenever samples are taken.

4 When consolidation of concrete is by rodding procedure. The concrete shall be placed inmould at 3 layers of equal height. Rod each layer 25 strokes. Rod the bottom layerthroughout its depth. Distribute the roddings uniformly over the cross section of the mould.For each upper layer, allow the rod to penetrate through the layer being rodded and into thelayer below about 25 mm. After each layer is rodded, tap the outsides of the mould lightly 10to 15 times with the mallet of 0.6 +0.2 kg, to close any holes left by rodding and to releaseany large air bubbles that may have been trapped. Use an open hand to tap light-gagesingle-use cylinder moulds which are susceptible to damage if tapped with a mallet.

5 When Self Consolidate Concrete is used, the concrete specimens shall not be consolidatedin moulds and it shall be placed in single lift then levelled with minimum manipulation.

6 All samples shall be moulded at jobsite on a levelled surface area to within 20 mm per meter

7 Immediately after moulding and finishing, the specimens shall be stored for a period up to 48h in a temperature range from 20 to 26

oC and in an environment preventing moisture loss

from the specimens

8 Specimens shall not be transported or handled until at least 8 h after final set

9 Transportation time from site to laboratory for final curing and strength testing shall notexceed 4 hours. Specimens shall be protected direct sun or rapid evaporation and placed on

cushion layer to reduce vibration

6.6 REJECTION OF CONCRETE MIXES

6.6.1 Rejection of Concrete Mixes:

1 Concrete mixes shall be rejected if they fail to meet one or more requirements, whichcannot be brought into compliance of visually unsatisfactory as related to any of thefollowing:

(a) Improper class of concrete

(b) Improper workability

(c) Overmixing

(d) Slump or temperature not within specified limits

(e) Oversized aggregate

(f) Maximum water-cementitious ratio is exceeded

6.6.2 Unsatisfactory Concrete Works

1 A test shall be the average of the strengths of the specimens tested at the age specified. If aspecimen shows definite evidence other than low strength, of improper sampling, molding,handling, curing, or testing, it shall be discarded and the strength of the remainingspecimens shall then be considered the test result and where the range of the test values is

more than 15 % of the mean, the results shall be disregarded unless an investigation


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reveals an acceptable reason to justify disregarding an individual test value. To conform tothe requirements of this specification, strength tests representing each class of concretemust meet the following requirements:

(a) The average of any three consecutive strength tests shall be equal to, or greater than,the specified strength, f c, and

(b) When the specified strength is 35 MPa or less, no individual strength test (average of atleast two specimen tests) shall be more than 3.5 MPa below the specified strength, f c

(c) When the specified strength is greater than 35 MPa, no individual strength test (averageof two specimen tests) shall be less than 0.90 f c.

2 Should any of the test results be unsatisfactory, the Engineer may order the work to bestopped pending his further instructions. Executed work for which test results areunsatisfactory shall be liable to rejection and if so advised the work shall be rebuilt at theContractor's expense.

3 In the case of the 7-day works cube tests proving unsatisfactory, the work may be stopped

but shall not be liable to rejection pending the result of the 28-day test. If the test results failto comply with the requirements, the work represented shall be immediately liable torejection. The Contractor may however be given the option of cutting three acceptablespecimens from the completed work and preparing from them test cores according to part 13of this section. Should the average strength of these specimens attain the minimum 28daystrength the work will be accepted but otherwise the work will remain liable to rejection asabove.

4 The cost of all such cuttings, preparation of specimens, transportation and testing, and ofmaking good the portions of the structure affected shall be borne by the Contractor.

5 Regardless of satisfactory test cube results, any concrete work which, in the Engineer'sopinion, is excessively honeycombed or in any other way is defective, shall be liable to

rejection. Minor defects apparent on stripping the formwork must be made good at theContractor's expense. No such repair work shall be carried out until after inspection by theEngineer and his acceptance of the proposed treatment has been given. Work which hasnot been previously inspected but which shows signs of such treatment shall be liable torejection as defective work.

6 The cost of all delays on site due to faulty concrete work shall be met by the Contractor.

END OF PART