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JKR CONCRETE SPECIFICATIONS 2014

BACKGROUND • • • •

Revision of the JKR Building Specifications started in 2012 involving Civil engineers and the Architects The specifications was completed 2014 and applied to all JKR Building projects in 2015 CKAS and CKJG were responsible for sections related to civil and Structural Engineering Works CKAS was responsible to Section D: Concrete Works

REASONS FOR THE REVISIONS • • • • • •

Update all references to the relevant Malaysian Standards which has undergone major changes through the adoption of European standards. Changes in MS 522 MS 522 (now MS EN 197) series on cement and MS 523 series on concrete Adoption design standards to MS EN . Moving forward from method specification to performance specification Introduction of IBS a must in JKR projects. Introduction of CIS 21 : 2016 by CIDB.

MATERIALS IN CONCRETE. • • •

Concrete = Aggregates + cement + water + admixtures Aggregates shall be naturally occurring sand, granite or limestone and comply with MS EN 12620 ( before was MS 29). Grading ans testing of aggregates maintain as in MS 30 Table 2 and Table 3

MATERIALS IN CONCRETE. • Major changes in the sub section on Cement. • In the old JKR Specification (Rev 2005) there are only 5 types of cements namely OPC, RHPC, SRPC, PPFAC(pfa), PSC (slag) • In the new JKR Specification there are now 27 types of cements namely 1 type of CEM I, 19 types of CEM II, 3 types of CEM III, 2 types of CEM IV and 2 types of CEM V.

MATERIALS IN CONCRETE. • • • •

Admixtures supplied shall comply with MS EN 934/BS EN 934-2. Not Chloride base. The use of super-plasticiser is allowed with special control tests in accordance with the latest standard and the manufacturer‘s recommendations. Admixtures acceptance test as in Table D4.

CLASSIFICATIONS OF CONCRETE MIXES • •

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In the old JKR Specification, two types of concrete mixes are specified which are Prescribed Mix and Designed Mix. MS 523 defines 5 types of concrete ie Prescribed Concrete, Designed Concrete, Designated Concrete, Standardised Prescribed Concrete, and Proprietary Concrete To ensure continuity with the old specification it was decided to cover only the first 2 types of concrete in the new JKR specification.

CLASSIFICATIONS OF CONCRETE MIXES • •

Prescribed Concrete and Designed Concrete specified in the new spcification have basically, have the same definitions as Prescribed and Designed Mix respectively. All the concrete mix shall comply with the recommendations of MS523-1 and MS523-2.

CLASSIFICATIONS OF CONCRETE MIXES • • •

PRESCRIBED CONCRETE may be used for the works of minor nature or involving a small quantity of concrete. Only CEM 1 cement are allowed and with no admixtures. Weight and volume batching are allowed . The prescribed concrete in the new JKR Specification retains Tables 5 & 6 of the old specification containing the formulation for prescribed mix and reproduce them without modification in Tables 5 & 5A.

CLASSIFICATIONS OF CONCRETE MIXES • • •

DESIGNED CONCRETE shall comply with the recommendations of MS523-1 and MS 523-2. The designed concrete is to be produced as site mixed or ready-mixed. The mix design submitted shall comply with the requirements specified in TABLE D6 and D6A.

CONCRETE GRADES • • •

The designed concrete grade to be used in the work shall be as stated in the Drawings. Concrete shall be designated as Grade C30/37 where ‘30' is minimum characteristic cylinder strength in N/mm2, and ‘37' is minimum characteristic cube strength in N/mm2. For prescribed mix, a suffix'P' shall be added after ‘30').The designed.

CEMENT CONTENT • •

The minimum cement content shall be in accordance with TABLE D6 and D6A, The maximum cement content shall not exceed 550 kg/m3 unless otherwise shown on the Drawings or as approved by the S.O.

CONCRETE DURABILITY •

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In old specification, Minimum Cement Content and Maximum Water-Cement ratio in Designed Mix is governed by exposure conditions categorised by broad descriptions in its table 6. In the new JKR Specification, the above values are similarly governed by exposure conditions but are more elaborately classified in Table D6.

CONSISTENCE OF CONCRETE • •

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The consistence of the fresh concrete shall be judged by its suitability for the condition of handling and placing. Consistence of the concrete shall be within one of the Limits: (i) Slump classes (Refer to TABLE D7) (ii) Compacting classes (Refer to TABLE D7A) (iii) Vebe classes (Refer to TABLE D7B) (iv) Flow classes (Refer to TABLE D7C) Consistence values expressed as slump and flow classes appropriate to different uses of concrete shall be as given in TABLE D7D.

Target Mean Strength & Current Margin • In the old specification, the contractor is responsible to ensure that the concrete mix is designed to have a target mean strength greater than the required grade by at least the current margin • The current margin shall be determined by the contractor as sub-section 3.2.1

Target Mean Strength & Current Margin • In the new JKR Specification it is specified that the targeted margin should be about twice the standard deviation which means at least a margin of 6 N/mm2 to 12 N/mm2. • Initially, the standard deviation (σ) shall be calculated from at least 35 consecutive test results taken over a period exceeding 3 months and which is immediately prior to the production period during which conformity is to be checked.

CONFORMITY AND IDENTITY TESTING •

The contractor is responsible for the evaluation of conformity for specified requirements of the concrete. For this purpose, the contractor shall carry out the following tasks: (i) Initial test, (ii) Production control including conformity control

CONFORMITY AND IDENTITY TESTING •

In the case of using a new concrete composition, initial testing shall be performed to provide a concrete that achieves the specified properties or intended performance with an adequate margin.

INITIAL TEST • In the old specification, the contractor shall carry out Trial Mix as follows • 3 separate batches of concrete • 6 cubes from each batch making a total of 18 • 9 cubes tested at 7-day and 9 cubes at 28-day • Average strength of 9 cubes tested at 28-day • shall exceed the characteristic strength by the current margin minus 3.5 N/mm2

INITIAL TEST • In the new JKR Specification, the contractor shall carry out Initial Test as follows • 3 separate batches of concrete • 3 specimens from each batch with a total of 9 • Average strength of 9 cubes tested at 28-day • shall exceed values of fck of Table D8 or D9 at least by the margin stated earlier

INITIAL TEST

SAMPLINGS

SAMPLINGS • In the new specifications, for both compliance testing and conformance testing a sample consists of 3 cubes where 1 cube is tested for the 7-day compressive strength and the remaining 2 cubes are tested for the 28day compressive strength • The average strength of the 2 cubes constitutes the 28day compressive strength of the sample

SAMPLINGS • For the new JKR Specification, in the sampling & testing plan and conformity criteria a distinction is made between • Initial production with less than 35 results • Continuous production with at least 35 results obtained over a period not exceeding 12 months • The minimum rate of sampling and testing of concrete shall be in accordance with table D10

CONFORMITY CRITERIA OF COMPRESSIVE STRENGTH • In the old specification, for compliance purpose both of following conditions must be satisfied • The mean strength determined from first 2, 3 of 4 consecutive test results or from any group of 4 consecutive results complies with the limits in column A of Table 8A of the specs. • Any individual test result complies with limits in column B of Table 8A.

CONFORMITY CRITERIA OF COMPRESSIVE STRENGTH

CONFORMITY CRITERIA OF COMPRESSIVE STRENGTH • In the new JKR Specification conformity of concrete compressive strength is assessed on specimens tested at 28 days in accordance with a) Groups of n non-overlapping or overlapping test results fcm (Criterion 1) b) Each individual test results fa (Criterion 2) • Conformity is confirmed if both criteria given in Table D11 for either initial or continuous production are satisfied.

CONFORMITY CRITERIA OF COMPRESSIVE STRENGTH

IDENTITY TESTING • Identity Testing in the New JKR Specification indicates whether the defined volume of concrete belongs to same population which conforms with the specified strength • JKR decided to adopt the same sampling rate as for compliance testing in the old specification. In future these rates may be reduced once there is more confidence with the concrete producers

IDENTITY TESTING

IDENTITY CRITERIOR OF COMPRESSIVE STRENGTH • In the new JKR Specification for concrete under production control certification • Identity of concrete is assessed for each individual strength test result and the average n non-overlapping discrete results as identified in Table D13 • Concrete is deemed to come from a conforming population if both criteria in Table D13 are satisfied for n results derived from strength tests on samples

IDENTITY CRITERIOR OF COMPRESSIVE STRENGTH

IDENTITY CRITERIOR OF COMPRESSIVE STRENGTH • For concrete not under production control certification • From the defined volume of concrete, at least 3 samples shall be taken for testing. The concrete is deemed to come from a conforming population if conformity for initial production is satisfied.

IDENTITY CRITERIOR FOR SLUMP AND FLOW.

CONTROL CHANGE IN THE CURRENT MARGIN • In the old specification, recalculation of the margin is carried out as described in 3.2.1 • The recalculated value is adopted if the two values differ by more than 18% for tests on 40 batches or more than 11% for tests on 100 batches or more than 5% for tests on 500 batches

CONTROL CHANGE IN THE CURRENT MARGIN • In the new JKR Specification, validity of the current margin is verified during subsequent production if the standard deviation of the latest 15 results S15 does not deviate from the initaily adopted standard deviation value (σ) as follows (method 1) • 0.63σ ≤ S15 ≤ 1.37σ • Where the value of S15 lies outside this limits a new estimate of σ shall be determined from last available 35 test results

CONTROL CHANGE IN THE CURRENT MARGIN • Alternatively in the new JKR Specification, provided approved by S.O. method 2 can be applied whereby a new value of σ is estimated from a continuous system but the sensitivity of the system should be at least that of method 1.

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