This section refers to the production of concrete, including concrete mix design, trial mix, testing and workmanship for concreting. The materials and workmanship standards shall include:
- Indonesian Standards equivalent to appropriate Japanese Standards - Japanese Industrial Standards (JIS)
- Standard Specifications for Concrete Structures - 2007.
- Year 2007 version of Public Building Works General Specifications (Building Works Edition) supervised by the Ministry of Land Infrastructure, Transport and Tourism, Minister's Secretariat Government Agency, Building Repair Division.
- Japanese Architectural Standard Specification for Reinforced Concrete Work JASS 5 (2009)
- Architectural Institute of Japan " Recommendation for Detailing and Placing of Concrete Reinforcement (2003) " equivalent International Standards.
4.1Materials
Constituent materials shall, except where otherwise described in the Engineer's requirements, sha ll be identified in the Contractor's Concreting Method Statement
and shall comply with the following:
4.1.1Portland Cement and PFA
Cement shall comply with Indonesian Standards, SNI 15-2049-2004, Japanese Standard JIS R 5210 or alternative International Standard. PFA may be used as a part-replacement for OPC; the maximum replacement sha ll not exceed 30%. PFA shall comply with Japanese Standards for Concrete Structures - 2007.
4.1.2Aggregate
(1)Sources of Aggregates
Prior to commencing any concrete work, the Contractor shall identify his type and sources of aggregate.
(2)Coarse Aggregate
Coarse aggregate shall be clean, hard, durable complying with the requirements of with applicable Indonesian Standards equivalent to Japanese Standard JIS A 1110,1102, 1137,1103,1145 or 1146,1141,5005,1121,1122, 1126,1103,1104.
(3)Fine Aggregate
Fine aggregate shall be clean, hard, durable complying with the requirements of with applicable Indonesian Standards equivalent to Japanese Standard JIS A 1109, 1102, 1137, 1103, 1105, JSCE-C502 or JSCE-C503, JIS A 1145 or 1146, 1141, 5005.
4.1.3Water
The water used in mixing or curing shall be clean and free from salt, oil or acid, organic material or other substance injurious to concrete or steel complying.
4.1.4Admixtures
Admixtures shall comply with applicable Indonesian Standards equivalent to Japanese Standard JIS A 6204 or alternative International Standard.
4.2Concrete Mix Design
4.2.1 Characteristic Strength of Concrete (Grade of Concrete)
The characteristic strength of concrete is the 28 days compressive strength based on cylinder test to Indonesian Standard, SNI 03-6813-2002, Japanese Standard JIS A 1108; Public Building Works General Specifications 6.4.6 or alternative International Standard.
4.2.2 Constituents of the Concrete Mix
The Contractor shall design the concrete mixes and detail them in his Method Statement.
4.2.3 Grading of Aggregates
The grading of the aggregates shall be within the limits as specified in Sub- Clause 5.1.2 of this Specification. Once the appropriate grading has been determined the Contractor shall include the detail in his Concreting Method Statement.
4.2.4 Workability
The concrete sha ll be of sufficient workability to permit full compaction.
The workability of a concrete mix sha ll be determined by slump testing performed in accordance with applicable Indonesian Standards equivalent to Japanese Standard JIS A 1101, or alternative International Standards.
The slump shall not normally be less than 75mm.
4.2.5 Cementitious Content
The total cementitious content sha ll not normally be less than 400kg/m' and the maximum amount of OPC sha ll not exceed 330kg/m'.
4.2.6 Water Content
The water/cement ratio shall not exceed 0.4.
4.3Quality Control of Concrete 4.3.1 General
Works concrete shall be tested and the results assessed as specified in Clause 4.4.
4.3.2 Control Standard
The control standard for all grades of concrete (other than 15N/mm') shall
be such that:
(1)The average of sets of three consecutive strength tests at 28 days shall be not less than the characteristic strength.
(2)No individual strength test (average of three cylinders) falls below the required 28 days strength by more than 3.5 N/mm'.
(3)In cases where, while the control standard set out in this Sub -Clause is being met yet, anyone cylinder tested is less than 85% of the characteristic strength then the Contractor shall take remedial action.
(4)The control standard of concrete work in association with its mix design shall be determined by the method described in Clause 4.4 which shall be applied to all test results as they become available.
Initial tests shall be carried out and if these show that the required standard of control is not being attained, the mix shall be withdrawn and redesigned.
4.4Testing of Concrete for Structures 4.4.1 General
The requirement of the quality control of concrete in association with its mix proportion shall be such that not more than 5.0 % of works concrete cylinders tested fall below the appropriate characteristic strength. In order to ensure, as soon as an adequate number of test results become available, that this specified requirement is being met, it is necessary to find the mean value and the
"standard deviation" of the available test results. On average, not more than 5.0
% of the test results shall have a strength less than the mean value minus 1.64 standard deviations. The standard deviation shall be obtained from not less than 30 results of test cylinders in which each result represents separate batches of the same strength concrete produced by the same plant under the same supervision.
4.4.2 Specifications
Sampling and testing shall be in accordance with applicable Indonesian Standards equivalent to appropriate Japanese Standards or alternative International Standards.
4.4.3 Standard Deviation (SD) SD = √U:(TV - AV)2 / (Ntv-1)) Where;
TV = Test Value AV = Average Value N = Number of tests
Samples shall be used to determine the genera l standard of quality control of the 28 days strengths of the concrete for a particular grade and mix of concrete. The concrete shall be deemed to comply with these
Specifications:
M28 - 1.64 (S) > L28 Where:
M28 = the average value of the 28 days test results L28 = the required 28 days cylinder strength 4.4.4 Samples for removal of formwork
(1)The appropriate strength requirements of each set of three cylinders of above shall be deemed to be satisfied if none of the strengths of the three cylinders is below the specified cylinder strength or the average strength of the three cylinders is not less than the specified cylinder strength.
4.4.5 Workability
For determining the workability of the concrete, one test shall be made on each load by Slump Test apparatus in accordance with applicable
Indonesian Standards.
4.5Failure to Meet Requirements
Should the strength indicated by the test specimens, made and tested in accordance with the preceding provisions, fall below the specified values, the Contractor shall raise a Non Conformance Report detailing his proposals to remedy the situation; actions may include:
1) Take and test core samples from in situ concrete
2) Designer reviews implication of failure relative to his design 3) Accept weaker concrete with justification
4) Revise mix design should problem be recurring