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JGJ 55-2011 English PDF (JGJ55-2011)

JGJ 55-2011 English PDF (JGJ55-2011)

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JGJ 55-2011: Specification for mix proportion design of ordinary concrete

This specification is applicable to the mix proportion design of ordinary concrete used for industrial/civil buildings and general structures.
JGJ 55-2011
JGJ
INDUSTRY STANDARD OF THE
PEOPLE REPUBLIC OF CHINA
UDC
P JGJ 55-2011
Registration No. J 64-2011
Specification for Mix Proportion Design of Ordinary Concrete
ISSUED ON: APRIL 22, 2011
IMPLEMENTED ON: DECEMBER 1, 2011
Issued by: Ministry of Housing and Urban-Rural Development of the PEOPLE Republic of China
Table of Contents
1 General Provisions ... 7
2 Terms and Symbols ... 8
2.1 Terms ... 8
2.2 Symbols ... 9
3 Basic Requirements ... 11
4 Determination of Concrete Compounding Strength ... 15
5 Calculation of Concrete Mix Proportion ... 17
5.1 Water-binder ratio ... 17
5.2 Water and Chemical Admixture Content ... 18
5.3 Binder, Mineral Additive and Cement Content ... 20
5.4 Ratio of Sand to Aggregate ... 20
5.5 Coarse and Fine Aggregates Content ... 21
6 Trial Mix, Adjustment and Determination of Mix Proportion ... 23
6.1 Trial Mix ... 23
6.2 Adjustment and Determination of Mix Proportion ... 23
7 Special Concrete ... 26
7.1 Impermeable Concrete ... 26
7.2 Frost-resistant Concrete ... 27
7.3 High Strength Concrete ... 28
7.4 Pumped Concrete ... 29
7.5 Mass Concrete ... 29
Explanation of Wording of This Specification ... 31
List of Quoted Standards ... 32
Explanation of Provisions ... 33
1 General Provisions
1.0.1 This specification is Formulated in order to regulate mix proportion design method of ordinary concrete, satisfy the requirements in design and construction, guarantee the concrete engineering quality, and make the engineering be of economic feasibility.
1.0.2 This specification is applicable to the mix proportion design of ordinary concrete used for industrial/civil buildings and general structures.
1.0.3 In addition to the requirements of this standard, the mix proportion design of ordinary concrete shall also meet the requirements of the relevant current standards of the nation. 2 Terms and Symbols
2.1 Terms
2.1.1 Ordinary concrete
Concrete with a dry apparent density of 2000kg/m3~2800kg/m3.
2.1.2 Stiff concrete
Concrete whose mixture slump is lower than 10mm and consistency needs be expressed in Vebe consistency (s).
2.1.3 Plastic concrete
Concrete with a mixture slump of 10mm~90mm.
2.1.4 Flowing concrete
Concrete with a mixture slump of 100mm~150mm.
2.1.5 High flowing concrete
Concrete with a mixture slump of not lower than 160mm.
2.1.6 Impermeable concrete
Concrete with a impermeability grade of not lower than P6.
2.1.7 Frost-resistant concrete
Concrete with a freezing resistance level of not lower than F50.
2.1.8 High strength concrete
Concrete with a strength grade of not lower than C60.
2.1.9 Pumped concrete
Concrete poured by force pump and transmission piping on the construction site. 2.1.10 Mass concrete
Structural concrete with large mass, in which harmful cracking may result from temperature stress caused by binder hydration heat.
2.1.11 Binder
General name of cement and active mineral additive in concrete.
2.1.12 Binder content
Content sum of cement and active mineral additive used in per cubic meter of concrete. 2.1.13 Water-binder ratio
Mass ratio of water content and binder content in concrete.
7 Special Concrete
7.1 Impermeable Concrete
7.1.1 The materials of impermeable concrete shall meet the following requirements: 1 The cement should be ordinary Portland cement;
2 Coarse aggregate should be of continuous gradation, the maximum nominal grain size hereof should not be greater than 40.0mm, the silt content shall not be larger than 1.0%, and the clod content shall not be larger than 0.5%;
3 Fine aggregate should be medium sand, the silt content hereof shall not be larger than 3.0%, and the clod content shall not be larger than 1.0%;
4 Impermeable concrete should be mixed with chemical admixture and mineral additive, and the grade of the fly ash added shall be level I or II.
7.1.2 Mix proportion of impermeable concrete shall meet the following requirements: 1 Maximum water-blinder ratio shall meet the requirements specified in Table 7.1.2; 2 Binder content per cubic meter of concrete should not be less than 320kg; 3 Ratio of sand to aggregate should be 35%~45%.
7.1.3 Concrete impermeability technical requirements in mix proportion design shall meet the following requirements:
1 Impermeability water pressure required impermeable concrete preparation shall be 0.2MPa higher than the design value;
2 Impermeability test results shall meet the requirements of following Formula: 2.010t ?€????
PP (7.1.3)
Where Pt -- Maximum hydraulic pressure value when no fewer than 4 in 6 test-pieces suffer from water seepage (MPa);
P --Impermeability grade specified in the design.
7.1.4 Air content test shall be carried out for impermeable concrete mixed with air entraining agent or air-entraining chemical admixture, and the air content should be controlled 3.0%~5.0%. 7.2 Frost-resistant Concrete
7.2.1 The materials of frost-resistant concrete shall meet the following requirements: 1 Cement shall be Portland cement or ordinary Portland cement;
2 Coarse aggregate should be of continuous gradation, the silt content shall not be larger than 1.0%, and the clod content shall not be larger than 0.5%;
3 The silt content of fine aggregate shall not be larger than 3.0%, and the clod content hereof shall not be larger than 1.0%;
4 Solidity test for coarse and fine aggregate shall meet the requirements of current professional standard ?€?Standard for Technical Requirements and Test Method of Sand and Crushed Stone (or Gravel) for Ordinary Concrete?€? JGJ 52.
5 Frost-resistant concrete with a freezing resistance grade not lower than F100 should be mixed with air entraining agent;
6 Chloride-contained antifreezing agent shall not be mixed in reinforced concrete or prestressed concrete; nitrite or carbonate contained antifreezing agent shall not be mixed in prestressed concrete.
7.2.2 Mix proportion of frost-resistant concrete shall meet the following requirements: 1 Maximum water-blinder ratio and minimum binder content shall meet the requirements specified in Table 7.2.2-1;
2 Addition percentage of compounded mineral admixture should meet the requirements of Table 7.2.2-2; and percentage of other mineral admixture should meet the requirements of Table 3.0.5-1 of this specification;
3 Minimum air content of concrete mixed with air entraining agent shall meet the requirements of Article 3.0.7 of this specification.
2.1.6 This article specifically refers to concrete designed with impermeability requirements; the impermeability grade shall not be lower than P6.
2.1.7 This article specifically refers to concrete whose design requires frost resistance. F50 is the lowest frost resistance grade for the classification of concrete?€?s frost resistance. 2.1.8 The definition of this article has been generally accepted by the concrete engineering industry. The definition of high-strength concrete in the technical specifications for the application of high-strength concrete that is being compiled is the same as this article. 2.1.9 Pumped concrete includes flowing concrete and high flowing concrete. The slump during pumping is not less than 100 mm, which is widely used.
2.1.10 Mass concrete can also be defined as: Large-volume concrete with a minimum geometric dimension of concrete structures not less than 1 m, OR concrete that is expected to cause harmful cracks due to temperature changes and shrinkage caused by hydration of cementitious materials in concrete.
2.1.11, 2.1.12 The terms and definitions of cementitious materials and cementitious material dosage have been generally accepted in the field of concrete engineering field. 2.1.13 With the widespread application of concrete mineral admixtures, the water-binder ratio has been widely used at home and abroad to replace the water-cement ratio. 2.1.14, 2.1.15 In this Specification, the percentage means relative mass percentage, whilst the consumption means absolute mass.
3 Basic requirements
3.0.1 The concrete mix proportion design shall not only meet the requirements for strength, but also the requirements for construction performance, other mechanical properties, long-term performance, durability. Emphasizing that concrete mix proportion design shall meet durability performance requirements is one of the focuses of this revision. 3.0.2 Based on the actual situation and technical conditions of aggregates in China, China has long used concrete mix proportion design based on dry aggregates in construction projects, which is operable and has good application conditions.
3.0.3 Controlling the maximum water-cement ratio is an important means to ensure the durability of concrete, wherein the water-binder ratio is the primary parameter in concrete mix proportion design. The current national standard ?€?Code for Design of Concrete Structures?€? GB 50010 stipulates the maximum water-binder ratio of concrete, under different environmental conditions.
3.0.4 Under the condition of controlling the maximum water-binder ratio, the minimum cementitious material consumption in Table 3.0.4 is the lower limit of the cementitious material consumption, that meets the construction performance of concrete and the durability performance of concrete, after adding mineral admixtures.
3.0.5 The maximum percentage of mineral admixtures is specified mainly to ensure the durability of concrete. The actual percentage of mineral admixtures in concrete is determined through tests. The durability test verification is specified in the mix proportion adjustment and determination steps of this Specification, to ensure that the concrete durability requirements proposed by the engineering design are met. When using a percentage that exceeds the maximum percentage of mineral admixture as given in Table 3.0.5-1 and Table 3.0.5-2, it is inappropriate to completely deny it. Once the safety and durability of structural concrete is proven, through comprehensive testing and demonstration of concrete performance, to mee the design requirements, it can still be adopted.
3.0.6 This Specification is concisely divided into four categories, according to the degree of environmental conditions affecting the corrosion of steel bars caused by chloride ions; stipulates the maximum chloride ion content in concrete under various environmental conditions. This Specification adopts the method of measuring chloride ions in concrete mixture. Compared with the method of testing chloride ions in hardened concrete, the time is greatly shortened, which is beneficial to the design and control of mix proportion. The chloride ion content in Table 3.0.6 is the percentage, as relative to the consumption of cement in concrete, which is safer than controlling the percentage of chloride ions relative to the amount of cementitious material in concrete.
3.0.7 Adding an appropriate amount of air-entraining agent is beneficial to the durability of concrete. Especially for concrete with higher frost resistance requirements, adding air-entraining agent can significantly improve the frost resistance of concrete. The percentage of air-entraining agent shall be appropriate. Too little air-entraining agent will not be effective enough. Too much air-entraining agent will cause a greater loss of concrete strength. 3.0.8 Controlling the alkali content in concrete within 3.0 kg/m3 and adding an appropriate amount of mineral admixtures, such as fly ash and granulated blast furnace slag powder, are of great significance to preventing alkali-aggregate reactions in concrete. The alkali content in concrete is the calculated sum of the measured alkali content of each raw material of concrete. The measured alkali content of mineral admixtures, such as fly ash and granulated blast furnace slag powder, is not the effective alkali content that participates in the alkali-aggregate reaction. For the effective alkali content in mineral admixture, the alkali content of fly ash shall be 1/6 of the actual measured value, the alkali content of granulated blast furnace slag powder shall be 1/2 of the actual measured value, which has been adopted by the concrete engineering industry.
4 Determination of compounding strength
4.0.1 The strength of concrete preparation shall have a sufficient guaranteed rate for the strength of concrete in production and construction. For concrete with a strength grade less than C60, practice has proven that the traditional calculation formula is reasonable, so the traditional calculation formula is still used; for concrete with a strength grade not less than C60, the traditional calculation formula can no longer meet the requirements; the formula 5.2.2 The admixtures in this section specifically refer to admixtures with water-reducing function.
5.2.3 This article has a guiding role, especially for those who lack experience and test data. In actual work, experienced professional technicians usually target meeting the performance of concrete and saving costs; determine the content of admixtures and water consumption for flowing or high flowing concrete, based on experience and tests.
5.3 Binder, mineral admixture and cement content
5.3.1 For concrete of the same strength grade, an increase in the percentage of mineral admixture will cause a corresponding decrease in the water-binder ratio. If the water consumption remains unchanged, the consumption of cementitious material, which is calculated according to formula (5.3.1), will also increase; meanwhile it may not be the most economical consumption of cementitious material. Therefore, the calculation result of formula (5.3.1) is only the initial calculated consumption of cementitious material. The actual consumption of cementitious material used shall be adjusted according to Article 6.1.4 of this Specification. Choose a more economical consumption of cementitious material, that meets the performance requirements of the mixture.
5.3.2, 5.3.3 The percentage of mineral admixture, which is used in calculating the mineral admixture consumption, is determined after comparing different percentages during the calculation of the water-binder ratio. The calculated consumption of cementitious materials, mineral admixtures, cement need to be adjusted and verified during the trial mix process. 5.4 Ratio of sand to aggregate
5.4.1, 5.4.2 This section provides guidance on the value of ratio of sand to aggregate, which has been proven to be basically consistent with reality, through practical application. In actual work, the ratio of sand to aggregate can also be initially selected based on experience and historical data. The ratio of sand to aggregate has a greater impact on the performance of the concrete mixture; the adjustable range is slightly wider, which is also related to the material cost. Therefore, the ratio of sand to aggregate selected in this section is only preliminary and needs to be adjusted during the trial mix process, to determine a reasonable ratio of sand to aggregate.
5.5 Fine aggregate and coarse aggregate content
5.5.1, 5.5.2 In actual projects, the quality method is usually used in concrete mix design. The volumetric method is also allowed to be used in concrete mix design, depending on specific technical needs. Compared with the mass method, the volumetric method needs to measure the density of cement and mineral admixtures, as well as the apparent density of aggregates, etc., which has slightly higher technical requirements.
6 Trial mix, adjustment and determination of mix proportion
6.1 Trial mix
6.1.1 The connotation of the mixing method, which is mentioned in this article, mainly includes the mixing method, feeding method, mixing time.
6.1.2 This article specifies the basic requirements for the molding of test pieces during the trial mix process.
6.1.3 If the mixing volume is too small, the representativeness of the mixture will be insufficient, due to factors such as the sticking factor of the concrete mixture slurry and insufficient volume.
6.1.4 During the trial mix process, the first step is to trial mix and adjust the concrete mixture. During the trial mix adjustment process, on the basis of calculating the mix proportion, it shall keep the water-binder ratio unchanged, use as a smaller amount of cementitious materials as possible. On the principle of saving cementitious materials, the amount of admixtures and ratio of sand to aggregate shall be adjusted to make the properties such as slump and workability of the concrete mixture meet the construction requirements, thereby proposing a trial mix proportion.
6.1.5 After the concrete mixture is adjusted and the trial mix proportion is formed, the concrete strength test begins. Neither the calculated mix proportion nor the trial mix proportion can guarantee whether the strength of the concrete preparation meets the requirements. The purpose of the concrete strength test is to compare the mix proportions of three different water-binder ratios, to obtain a mix proportion, with qualified prepared strength as well as economical and reasonable cementitious material content. Since the concrete strength test is carried out after the concrete mixture is properly adjusted, the performance of the concrete mixture using three different water-binder ratios for the strength test shall remain unchanged, that is, the water consumption shall be kept unchanged, the cementitious material shall be increased and decreased, the ratio of sand to aggregate shall be reduced or increased accordingly, the percentage of admixture shall also be fine-tuned by decreasing or increasing.
In the absence of special provisions, the concrete strength specimens shall be subjected to compression tests at the 28d age. When the design strength of other ages such as 60d or 90d is specified, the concrete strength specimens shall be subjected to the compression test at the corresponding age.
6.2 Adjustment and determination of mix proportion
6.2.1 By drawing the relationship between strength and binder-water ratio, or using the interpolation method, it is safer to select a binder-water ratio corresponding to a strength slightly greater than the prepared strength for further mix proportion adjustment. It can also directly use one of the three binder-water ratio concrete strength tests, as mentioned above, that satisfies the prepared strength, for further mix proportion adjustment. Although it is relatively simple, sometimes there may be more strength surplus and the economic cost is slightly higher.
6.2.2, 6.2.3 Concrete mix proportion refers to the content of various materials per cubic meter of concrete. In the process of mix proportion calculation, concrete trial mix and mix 7.2.1 It is a basic practice to use Portland cement or ordinary Portland cement to prepare frost-resistant concrete. This is generally done in cold or severe cold areas. Aggregates containing more mud (including mud blocks) and poor aggregate solidity are detrimental to the frost resistance of concrete. Some concrete antifreezes are mixed with chlorine salts, which can cause corrosion of the steel bars in the concrete, leading to serious structural concrete durability problems. The current national standard "Code for utility technical of concrete admixture" GB 50119 stipulates that antifreeze containing nitrite or carbonate is strictly prohibited from being used, in prestressed concrete structures. 7.2.2 A large water-binder ratio of concrete will result in poor compactness and adverse frost resistance. Therefore, the maximum water...

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