Microsoft Word C041261e doc Reference number ISO 22965 2 2007(E) © ISO 2007 INTERNATIONAL STANDARD ISO 22965 2 First edition 2007 04 01 Concrete — Part 2 Specification of constituent materials, produc[.]
General
When using constituent materials governed by International Standards, the relevant requirements must be followed In cases where International Standards do not exist for certain materials, the standards referenced in the national annex, typically regional or national standards, will apply.
Constituent materials must be free from harmful ingredients that could negatively impact the strength, consistency, setting time, and durability of concrete, as well as prevent corrosion of reinforcement Additionally, these materials should be appropriate for their intended use in concrete applications.
Materials that comply with the relevant International Standards in ISO 22965 are considered safe, as they do not contain harmful substances in amounts that could negatively affect concrete durability or cause reinforcement corrosion, provided that the concrete meets specified limits, such as maximum chloride content.
Only constituent materials with established suitability for the specified application shall be used in concrete conforming to this part of ISO 22965
NOTE 1 Where general suitability is established for a constituent material, this does not indicate suitability in every situation and for every concrete composition
NOTE 2 This part of ISO 22965 lists constituent materials conforming to International Standards that have general suitability The national annex extends these lists of constituent materials with approved general suitability
Where types and classes of constituent materials are not detailed in the specification, the producer shall select constituent materials for the specified requirements only.
Cements
General suitability is established in the national annex for cements conforming to a standard listed in the same annex
NOTE The following types of cement have characteristics specified in regional and national standards:
Cements can be specified in grades based on the 28-day strength in mortar (e.g 32,5 MPa, 42,5 MPa and 52,5 MPa), and as normal hardening, rapidly hardening or slowly hardening cements.
Additions
5.3.1 General suitability is established in the national annex for type I additions of the following types:
⎯ filler aggregate conforming to a standard listed in the same annex;
⎯ pigments conforming to a standard listed in the same annex
5.3.2 General suitability is established in the national annex for type II additions of the following types:
⎯ fly ash conforming to a standard listed in the same annex;
⎯ silica fume conforming to a standard listed in the same annex;
⎯ ground-granulated blast-furnace slag (GGBS) conforming to a standard listed in the national annex.
Aggregates
General suitability is established in the national annex for aggregates conforming to a standard listed in the same annex
The maximum aggregate size shall not be greater than the value specified
NOTE 1 See the national annex for the test method Most test methods permit a small proportion of over-sized particles
Light-weight aggregates must meet specific criteria, including a maximum acid-soluble sulfate content of 0.1% by mass and a loss-on-ignition limit of 10% by mass for furnace-bottom ash or clinker, as detailed in the national annex for testing methods.
When specifying freezing- and thawing-resistant, lightweight aggregates, the producer must provide data that proves these aggregates yield concrete with sufficient resistance to freezing and thawing.
Freezing and thawing resistance is considered sufficient if aggregates have been successfully used for at least 10 years in comparable or harsher conditions with concrete of equal or lower quality An alternative approach to assess this resistance involves conducting relative freezing and thawing tests on concrete in water or a salt solution, as applicable If this method is employed, the testing procedure and compliance criteria must be outlined in the national annex.
All-in aggregate shall be used only in concrete with compressive strength classes u B12
Aggregate recovered from wash water or fresh concrete may be used as aggregate for concrete
Undivided recovered aggregate should not exceed 5% of the total aggregate unless permitted by the national annex If the amount of recovered aggregates surpasses this limit, they must match the type of primary aggregate, be separated into coarse and fine fractions, and comply with the aggregate specifications.
Mixing water
General suitability is established in the national annex for mixing water conforming to a standard listed in the same annex
Recycled water from concrete production must be utilized following the specified conditions outlined in a mixing-water standard of established suitability or according to the guidelines provided in the national annex.
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Admixtures
General suitability is established in the national annex for admixtures conforming to a standard listed in the same annex
The total amount of admixtures, if any, should not exceed the maximum dosage recommended by the admixture producer
Admixtures used in quantities less than 2 g/kg of cement shall be dispersed in part of the mixing water unless otherwise specified in the national annex
At higher levels of use, the producer may select the method of dispersal
When the total amount of liquid admixtures in concrete exceeds 3.0 l/m³, the water content must be considered in the calculation of the water/cement ratio, unless stated otherwise in the national annex.
Where more than one admixture is used, the compatibility of the admixtures shall be checked in the initial tests
Requirements for composition of concrete
The selection of concrete composition and constituent materials must meet the specified requirements for both fresh and hardened concrete, including consistency, density, strength, durability, and corrosion protection for embedded steel Additionally, the production process and the intended execution method of the concrete works should be considered Requirements for the use of additions are outlined in the national annex.
Where not detailed in the specification, the producer shall select types and classes of constituent materials from those with established suitability for the specified environmental conditions
The concrete should be designed so as to minimize segregation and bleeding of the fresh concrete
6.1.2 Resistance to alkali-aggregate reaction
Deleterious alkali-aggregate reaction shall be avoided using procedures specified in the national annex or the project specification
The quantities of type I and type II additions used in concrete shall be covered by the initial tests
The influence of high quantities of additions on properties other than strength should be taken into account
For designed concrete, the use of additions shall conform to the requirements specified in the national annex or the project specification
Type II additions in accordance with section 5.3 can be included in the calculations for cement content and the water/cement ratio, following the k-value concept as allowed by the national annex.
The k-value concept is detailed in Annex F, while additional k values, various types of cements, and different additions, including type I, may be specified in the national annex.
The chloride content of the concrete shall not exceed the value specified in the national annex or the project specification
Calcium chloride and chloride-based admixtures shall not be added to concrete containing steel reinforcement, pre-stressing steel reinforcement or other embedded metal
The method for determining the chloride content of constituent materials is specified in Table 1
Table 1 — Method for determining the chloride content of constituent materials
Cement, fly ash, ground-granulated blast-furnace slag (GGBS), limestone fines, pulverized fuel ash (PFA), metakaolin See national annex
Water a ISO 9297 a Testing is not required if the water is from a potable supply.
To determine the chloride content in concrete, it is essential to calculate the total contributions from the constituent materials using one or a combination of specified methods.
⎯ calculation based on the maximum chloride content of the constituent either permitted in the standard for the constituent or declared by the producer of each constituent material;
The monthly calculation of chloride content in constituent materials is determined by summing the means of the last 25 chloride determinations and adding 1.64 times the calculated standard deviation for each material.
NOTE The latter method is particularly applicable to sea-dredged aggregates and for those cases where there is no declared or standard maximum value
For the determination of the chloride content of the concrete, the measurement of freshly mixed trial mixtures by means of methods defined in the national annex may be applied.
Requirements for fresh concrete
The consistency of concrete, whether at the time of use or for ready-mixed concrete upon delivery, must adhere to the limits specified in section 9.3, as outlined in Table 2.
When a slump class is defined, the measurement should be taken at the highest point If a target slump is indicated, it should also be measured at the highest point, unless otherwise stated in the national annex.
Table 2 — Method for measuring consistence
When concrete is delivered via a truck mixer or agitating equipment, its consistency can be assessed by taking a spot sample from the initial discharge This sample should be collected after approximately one discharge.
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Admixtures or water may be added on site according to the national annex or project specifications, following a documented procedure to achieve the desired consistency without exceeding specified limits The national annex may outline procedures for this addition, and any extra admixtures or water must be recorded on the delivery ticket For details on remixing, refer to Clause A.5.
The party who authorizes this addition is responsible for the consequences The requirements for this authorization shall be provided in the national annex
6.2.2 Cement content and water/cement ratio
The content of cement, water, or additives must be determined based on the batch recorder's print-out or, in the absence of recording equipment, from the production record associated with the batching instructions.
The water/cement ratio in concrete is calculated based on the specified cement content and effective water content, as outlined in section 5.6 regarding liquid admixtures Additionally, the water absorption of both normal-weight and heavyweight aggregates must be assessed following the method provided in the national annex For coarse, lightweight aggregates in fresh concrete, the water absorption should also be determined according to the national annex guidelines.
For fine light-weight aggregate, the test method and criteria should be specified or declared by the producer
The determination of cement content, addition content, or water/cement ratio in fresh concrete requires analysis, and the test methods along with tolerances must be mutually agreed upon by the specifier and the producer.
The cement content and water/cement ratio shall be within the limits given in 9.3
The air content of concrete must be measured according to ISO 1920-2 for normal-weight and heavyweight concrete For lightweight concrete, the measurement should follow the method specified in the national annex It is essential that the air content remains within the limits outlined in section 9.3.
To accurately measure the temperature of fresh concrete, two methods are recommended First, within 2 minutes of sample delivery, a type A 100 mm immersion thermometer that meets ISO 1770 standards should be inserted into the sample to a depth of at least 100 mm After maintaining steady conditions for 1 minute, the temperature should be recorded to the nearest 1 °C Alternatively, a different temperature-measurement device with precision comparable to an ISO 1770 thermometer can be used to capture the steady-state temperature, also to the nearest 1 °C.
The temperature of fresh concrete at the time of delivery must be at least 5 °C or meet the specified minimum value, and it should not exceed the designated upper limit.
Requirements for hardened concrete
Compressive strength is denoted as \$f_{c,cyl}\$ for cylindrical specimens, which should have a length twice the diameter, and as \$f_{c,cube}\$ for cubical specimens, following the guidelines of ISO 1920-1, ISO 1920-3, and ISO 1920-4 The diameter of the cylinder or the side length of the cube must be at least three times the maximum aggregate size Alternative curing methods may be utilized for strength assessment, provided that their relationship to the standards in ISO 1920-3 is accurately established and documented.
The producer must specify before delivery whether the compressive strength will be evaluated using cylinder or cube tests, along with the dimensions of the specimen to be utilized.
Unless otherwise specified, the compressive strength shall be determined on specimens tested at 28 days
NOTE For particular uses, it can be necessary to specify the compressive strength at ages earlier or later than
28 days (e.g for massive structural elements) or after storage under special conditions (e.g heat treatment)
The characteristic strength of concrete must meet or exceed the minimum compressive strength specified for its class, as outlined in Tables 3 and 4 For intermediate strength classes not listed, the minimum strength can be determined through interpolation Compliance with the criteria for compressive strength in Clause 9 allows for the assumption that the minimum characteristic strength has been achieved.
Table 3 — Compressive strength classes for normal-weight and heavy-weight concrete
Minimum characteristic cube strength a f ck,cy l f ck,cube
B120 120 140 a Other values may be used if the relationship between these and the reference cylinder strength is established with sufficient accuracy and is documented.
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Table 4 — Compressive strength classes for light-weight concrete
Minimum characteristic cube strength a f ck,cy l f ck,cube
LB80 80 88 a Other values may be used if the relationship between these and the reference cylinder strength is established with sufficient accuracy and is documented
The tensile splitting strength of concrete shall be measured in accordance with ISO 1920-4 Unless otherwise specified, the tensile splitting strength shall be determined on specimens tested at 28 days
The concrete's characteristic tensile splitting strength must meet or exceed the specified value Compliance with the criteria outlined in Clause 9 ensures this requirement is satisfied.
For normal-weight concrete, the oven-dry density shall be greater than 2 000 kg/m 3 and not exceed
The target density for concrete, whether light-weight or heavy-weight, is typically set at 2,600 kg/m³, although national annexes may establish different limits To ensure compliance with this target density, the density of hardened light-weight concrete must be determined following ISO 1920-5, either in an oven-dry condition or as specified.
The measured density shall be within the limits given in Clause 9
When test specimens are tested for resistance to water penetration, the method and compliance criteria shall be specified
In the absence of an acceptable test method, resistance to water penetration may be specified indirectly by limiting values for concrete composition
Concrete is classified as a material that does not necessitate a reaction-to-fire test It consists of natural aggregates, cement, admixtures, additions, or other inorganic constituent materials, all conforming to specific standards.
General
All concrete shall be subjected to a documented production-control system under the responsibility of the producer
Production control shall be comprised of all measures necessary to maintain the properties of concrete in compliance to specified requirements, including
⎯ use of the results of tests on constituent materials, fresh and hardened concrete and equipment,
⎯ where relevant, inspection of equipment used in transporting fresh concrete
These requirements shall be appropriate for the kind and size of the production, the works, the particular equipment, the procedures and the rules specified in the national annex
The production-control system should take account of the principles of a quality management system, such as ISO 9001
NOTE Guidance on a “benchmark” production-control system is given in Annex A.
Production-control systems
A documented production-control system, or production-control manual, must clearly define the responsibilities, authority, and interrelations of all personnel involved in managing, performing, and verifying work that impacts concrete quality.
NOTE This particularly concerns personnel who need the organizational freedom and authority to minimize the risk of non-conforming concrete and to identify and record any quality problem
The production-control systems shall be specified in a national annex in a combination of compliance controls and compliance criteria
Producers must investigate any failure to meet production process and control requirements If this leads to non-compliance with Clause 9 or concrete specifications, the concrete must be declared non-conforming It is essential to promptly identify and rectify the causes of any non-compliance in the production process and control.
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7.2.1 Requirements for the production-control system — Compliance based on option A
The production-control system adhering to option A must comply with Clause 9 and any specific project specifications for concrete Under option A, it is essential to maintain production in a state of statistical control.
7.2.2 Requirements for the production-control system — Compliance based on option B
Compliance is based on concrete families corresponding to option B, where sampling and testing for production control of normal-weight and heavy-weight concrete strength classes from B8 to B50, or light-weight concrete from LB8 to LB50, should ideally be conducted on established concrete families as determined by the producer It is important to note that light-weight concrete and self-compacting concrete must not be mixed with families of normal-weight concrete, although light-weight concretes with similar aggregates can be grouped into their own family.
To enhance production control in concrete manufacturing, it is advisable to categorize multiple concrete types into families This approach can greatly reduce the time taken to identify and respond to changes in the production process.
NOTE 1 For guidance for the selection of concrete families, see Annex B
The producer of concrete families is responsible for overseeing all family members, ensuring that sampling is conducted across the entire spectrum of concrete compositions produced within that family.
For effective production control within a concrete family, a reference concrete is chosen, typically representing the most commonly produced mix or a mid-range composition This reference concrete serves as a benchmark, allowing for the establishment of relationships between each specific concrete composition and the reference Consequently, this enables the normalization of compressive strength test results from individual concrete samples to align with the reference concrete.
The relationships between family members shall be reviewed on the basis of original compressive strength test data at every assessment period
Where compliance is based on option B (see 9.4.3), the production-control system shall have the following characteristics unless otherwise specified in the national annex:
⎯ system for predicting 28 day strength from earlier strength testing and the use of these data until the actual 28 day strengths are determined;
⎯ continual monitoring of the achieved mean strength, standard deviation and the correlation between the early strength and 28 day strength data;
⎯ target mean strength set at a level W (f ck + 2σ);
⎯ assumed minimum standard deviation of 3,0 N/mm 2 ;
⎯ initial estimate of the population standard deviation for a concrete or concrete family is based on at least
35 results taken over a period not exceeding 12 months;
The system is designed with a sensitivity that can accurately detect genuine changes in mean strength of \$u = 0.5\sigma\$ over an average run length of 35 results Additionally, it is capable of identifying real changes in standard deviation that meet or exceed specified criteria.
Where the actual mean strength is more than 0,5σ below the target mean strength, the mix proportions shall be adjusted to achieve the target value
Where s 15 > 1,37σ, a new design value of standard deviation shall be adopted and the mix proportions adjusted accordingly
The production control requirements outlined are adequate to ensure a high likelihood of meeting the specified characteristic strengths throughout the assessment period, eliminating the need for additional compliance checks Each batch must be evaluated according to the criteria in section 9.3, and for especially critical lots, identity testing may be conducted to verify that the concrete originates from a compliant population.
When the actual mean strength exceeds the target mean strength or the actual standard deviation is less than the current value, adjustments to the mix proportions become optional.
Testing
The testing shall be performed in accordance with
⎯ the test methods given in this part of ISO 22965 (reference test method),
⎯ other test methods if the correlation or safe relationship between the results of these test methods and the reference methods have been established
The accuracy of the safe relationship or correlation must be evaluated at regular intervals This assessment should be conducted individually for each production site operating under varying conditions, unless specified otherwise in the national annex.
Delivery ticket for ready-mixed concrete
At delivery, the supplier shall provide a delivery ticket for each delivery of concrete on which is printed, stamped or written at least the following information:
⎯ name of the ready-mixed concrete plant;
⎯ serial number of the ticket;
⎯ date and time of loading, i.e time of first contact between cement and water;
⎯ truck number or vehicle identification;
⎯ name of user or purchaser;
⎯ name and location of the site;
⎯ details or references to specifications, e.g code number, order number;
⎯ amount of concrete in cubic metres;
⎯ declaration of compliance with reference to the specifications;
⎯ name or mark of the certification body, if relevant;
⎯ time at which the concrete arrives on site;
⎯ time of the beginning of unloading;
⎯ time of the end of unloading;
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⎯ consistence class or target value;
⎯ limiting values of concrete composition, if specified;
⎯ type of admixture and addition, when used;
⎯ target density in the case of light-weight or heavy-weight concrete;
⎯ strength class of the cement in the case of prescribed concrete.
Delivery information for site-mixed concrete
For site-mixed concrete, especially in large areas or when multiple concrete types are used, it is essential to include the information specified in section 8.1 on the delivery ticket This is particularly important when the concrete producer differs from the party responsible for its placement.
Transport of concrete
8.3.1 Transport to the point of delivery
Concrete shall be transported in a) a truck mixer or agitator, or b) a non-agitating vehicle where permitted by the specifier
Where non-agitating vehicles are used, procedures shall be followed that have been proven to minimize
⎯ any change in entrained air content, except for the case where the loss of air has been taken into account;
⎯ ingress of foreign matter or water
Concrete must be delivered fresh and meet specified requirements It should be transported in truck mixers or agitators within 2.5 hours of mixing, or within 1.5 hours if using non-agitating equipment, unless otherwise specified.
In cool, humid conditions or when using specific additives like ground-granulated blast-furnace slag (GGBS), fly ash, or retarding admixtures, a longer loading time may be suitable Conversely, in hot weather with cement-rich concretes or when accelerating admixtures are applied, a shorter loading time is crucial.
9 Compliance control and compliance criteria
General
The compliance or non-compliance is judged against the compliance criteria Non-compliance can lead to further action at the place of production and on the construction site
Where tests for production control are the same as those required for compliance control, they are permitted to be used for the verification of compliance.
Sampling and testing plan
For compliance tests, sampling locations must be selected to ensure that the concrete properties and composition remain consistent from the sampling site to the delivery point Specifically, when dealing with light-weight concrete made from unsaturated aggregates, samples should be collected at the delivery location.
Samples of concrete shall be randomly selected and taken in accordance with ISO 1920-1 Sampling shall be carried out on concrete produced under conditions that are deemed to be uniform
The minimum sampling and testing rate for concrete must align with a national annex or relevant reference for national complementary provisions In the absence of specified minimum test rates, the recommended values in Table 5 should be applied Additionally, the national annex will define the volume of production for a production day; if not defined, this volume is set at 20 m³.
Samples of concrete must be collected after the addition of water or admixtures, with the producer responsible for this process However, it is acceptable to sample before the addition of plasticizers or super-plasticizers if prior testing confirms that their use in the specified amounts does not adversely affect the concrete's strength or air content, as outlined in section 6.2.1.
The test result is determined from an individual specimen or the average of multiple specimens tested at the same age If the test values from two or more specimens derived from one sample exceed 15% of the mean, those results will be disregarded unless a valid justification for an individual test value is provided through investigation.
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Table 5 — Recommended minimum rate of sampling for assessing compliance of compressive strength
Minimum rate of sampling a, b, c Production subsequent to first 50 m 3
Method of production assessment First 50 m 3 of production Concrete with production-control certification
Concrete without production-control certification
Option B Not applicable 1 per 400 m 3 or
For each production day, a sampling must be conducted, ensuring that no more than one sample is taken for every 25 m³ Additionally, the 28-day strength test data collected for production control will be utilized to evaluate compliance The minimum test rate is defined as the value that results in the highest sampling rate.
Compliance of an individual batch or load
The compliance criteria for an individual batch may be given in the national annex; if criteria are not given in the national annex, Tables E.1 to E.4 shall be used
The producer, if he detects a non-conforming batch, shall inform the user.
Compliance over an assessment period
The production shall be assessed using either option A (see 9.4.2) or option B (see 9.4.3)
Option A is applicable to continuous production when the production-control system meets the criteria outlined in section 7.2.1 Additionally, Option A is relevant for initial production scenarios, specifically when there are fewer than 35 results available for a particular concrete mix.
The application of concrete families for compliance under option A is restricted to scenarios where it serves as a precursor to option B Refer to section 7.2.2 for specific limitations regarding the concrete family.
When the compressive strength, denoted as \$f_{ck}\$, is defined, the mean compressive strength \$f_{cm}\$ for each set of three non-overlapping results must adhere to the following equation: \$f_{cm} = W(f_{ck} + \delta_{c})\$ The value of \$\delta_{c}\$ can be specified in the national annex, determined by local provisions, or assigned a default value of 4 N/mm² if not specified.
When the tensile splitting strength, denoted as \$f_{tsk}\$, is defined, the mean tensile splitting strength, \$f_{tsm}\$, for each set of three non-overlapping results must be calculated using the formula \$f_{tsm} = W(f_{tsk} + \delta_t)\$ The value of \$\delta_t\$ can be specified in the national annex, determined by local provisions, or set at an assigned value of 0.5 N/mm² if not specified.
9.4.2.4 Where the producer undertakes the compliance control, he shall inform the specifier as soon as practicable when non-compliance is detected
Option B applies to initial production and continuous production where the production-control system conforms to the requirements in 7.2.2
There are no additional compliance requirements for an assessment period other than those for an individual batch
NOTE 1 With option B, third-party certification is recommended or an equivalent level of independent control
NOTE 2 A specifier who wishes to independently check if a series of batches comes from a conforming population can refer to ISO 22965-1:2007, Annex C
General
The producer is responsible for evaluating compliance with the specified concrete requirements to ensure the validity of claims made, such as those on the delivery ticket This evaluation includes conducting initial tests as necessary, performing compliance control as outlined in Clause 9, and for option A, confirming that the process is statistically controlled.
For pre-cast concrete products, the requirements and provisions for the evaluation of compliance shall be given in the relevant technical specifications (product standards and technical approvals).
Assessment, surveillance and certification of production control
In accordance with project specifications or national annex requirements, the producer's production control must be evaluated and inspected by an approved body, followed by certification from an accredited certification organization, as outlined in Annex C.
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Guidance on a “benchmark” production-control system
A.1 Recorded data and other documents
Management should review the production-control system every two years to ensure its effectiveness and suitability Records of these reviews must be kept for a minimum of three years, unless longer retention is mandated by legal requirements.
All production control data must be documented, as shown in Table A.1 These records should be kept for a minimum of three years, unless legal requirements dictate a longer retention period.
Table A.1 — Recorded data and other documents, where relevant Subject Recorded data and other documents
Specified requirements Contract specification or summary of requirements
Cements, aggregates, admixtures, additions Name of suppliers and sources
Tests on mixing water (not required for potable water) Date and place of sampling
Test results Tests on constituent materials Date and test results
Composition of concrete Concrete description
Record of masses of constituents in batch or load (e.g cement content)
Water/cement ratio Chloride content Code of family member, if adopted Tests on fresh concrete Date and place of sampling
Location in structure, if known Consistence (method used and results) Density, where required
Concrete temperature, where required Air content, where required
Volume of concrete batch or load tested Number and codes of specimens to be tested Water/cement ratio, where required
Tests on hardened concrete Date of testing
Code and ages of specimens Test results for density and strength Special remarks (e.g unusual failure pattern of specimen) Evaluation of compliance Compliance/non-compliance with specification
Subject Recorded data and other documents
Additionally for ready-mixed concrete Name of purchaser
Location of work, e.g the construction site Numbers and dates of delivery tickets related to tests Delivery tickets
Additionally for pre-cast concrete Additional or different data may be required by the relevant product standard
A.2 Concrete composition and initial testing
When utilizing a new concrete composition, it is essential to conduct initial testing to ensure the concrete meets the specified properties and performance standards with a sufficient margin However, if there is extensive experience with a similar concrete type, initial testing may be waived Significant changes in constituent materials necessitate a re-evaluation of the concrete design and its relationships Additionally, no initial testing is required for prescribed or standardized prescribed concrete.
New concrete compositions obtained by interpolation between known concrete compositions or extrapolations of compressive strength not exceeding 5 N/mm 2 are deemed to satisfy the requirements for initial testing
Periodic reviews of concrete compositions are essential to ensure that all designs meet current requirements This process considers changes in the properties of constituent materials and the outcomes of production and compliance testing on the concrete mixtures.
The initial test must ensure that the concrete meets all specified criteria for both fresh and hardened states If the producer or specifier can provide sufficient design evidence from prior tests or extensive experience, this may serve as a valid substitute for initial testing.
NOTE Initial tests are the responsibility of the producer for designed concrete, the specifier for prescribed concrete and the standardization body for standardized prescribed concrete
Initial tests should be performed before using a new concrete or concrete family
Initial tests should be repeated when there is a significant change either in the constituent materials or in the specified requirements on which the previous tests were based
In general, initial tests should be carried out on fresh concrete at a temperature of 15 °C to 22 °C
When concreting on site under varying temperature conditions or when applying heat treatment, it is essential to inform the producer about any impacts on the concrete's properties and the necessity for additional testing.
For the initial testing of concrete, it is essential to test a minimum of three specimens from each of three different batches When the initial test pertains to a concrete family, the sampling should cover the entire composition range of that family, allowing for a reduction to one batch per concrete.
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The strength of a concrete batch is determined by averaging the test results, with the initial test reflecting the average strength of all batches.
The time between mixing and consistence testing and the results should be recorded
A greater number of tests is essential for determining the composition of a standardized concrete mix that includes all approved materials for national use The findings from these initial tests must be recorded with the appropriate standardization authority.
A.2.4 Criteria for adoption of initial tests
When evaluating the properties of fresh concrete, it is essential to consider the variations in mixer type and mixing procedures used during initial testing compared to those employed in actual production.
The concrete's compressive strength must surpass the values of f ck listed in Tables 3 or 4 by a sufficient margin, which should be at least double the anticipated standard deviation.
The adoption of initial tests for standardized prescribed concrete is determined by the mean compressive strength, \( f_{cm} \), measured in newtons per square millimetre, as outlined in Equation (A.1): \[f_{cm} = W f_{ck} + \alpha_a\] where \( \alpha_a \) represents a specific parameter.
⎯ is a value that should be specified in a national annex, or
⎯ is the value of 12 if no value is given in the national annex
The consistency of concrete must adhere to the specified limits of its consistency class at the time of placement or delivery, particularly for ready-mixed concrete.
For other properties that are specified, the concrete should meet the specified values with an appropriate margin
Knowledge, training and experience of personnel involved in production and production control should be appropriate to the type of concrete, e.g high-strength concrete, light-weight concrete
Appropriate records of the training and experience of the personnel involved in production and production control should be maintained
NOTE In some countries, there are special requirements regarding the level of knowledge, training and experience for the different tasks
Proper storage and handling of constituent materials are essential to prevent significant changes in their properties due to climate effects, contamination, or intermingling Ensuring compliance with relevant standards is crucial.