1 General Provisions
1.0.1 This Regulation 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 Regulation 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 2000 kg/m3~2800 kg/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 10 mm~90 mm.
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 160 mm.
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.
2.1.14 Percentage of mineral admixture
Mass percent of mineral additive in concrete binder content.
2.1.15 Percentage of chemical admixture
Mass percent of chemical admixture relative to binder content in concrete.
2.2 Symbols
fb——Compression strength measured value of binder 28d mortar (MPa);
fce——Compressive strength of 28d cement mortar (MPa);
fce, g——Cement strength grade (MPa);
fcu, 0——Compounding strength of concrete (MPa);
fcu, i——Strength of test-piece in group i (MPa);
fcu, k——Standard value of concrete cube compressive strength (MPa);
ma——Content of chemical admixture per cubic meter of concrete (kg/m3);
ma0——Content of chemical admixture per cubic meter of concrete in mix proportion calculation (kg/m3);
mb——Content of binder per cubic meter of concrete (kg/m3);
mb0——Content of binder per cubic meter of concrete in mix proportion calculation (kg/m3);
mc——Content of cement per cubic meter of concrete (kg/m3);
mc0——Content of cement per cubic meter of concrete in mix proportion calculation (kg/m3);
mcp——Assumed mass of concrete mixture per cubic meter (kg/m3);
mf——Content of mineral additive per cubic meter of concrete (kg/m3);
mf0——Content of mineral additive per cubic meter of concrete in mix proportion calculation (kg/m3)
mfcu——Mean value of strengths of n groups of test-pieces (MPa);
mg——Content of coarse aggregate per cubic meter of concrete (kg/m3);
mg0——Content of coarse aggregate per cubic meter of concrete in mix proportion calculation (kg/m3)
ms——Content of fine aggregate per cubic meter of concrete (kg/m3);
ms0——Content of fine aggregate per cubic meter of concrete in mix proportion calculation (kg/m3);
mw——Content of water per cubic meter of concrete (kg/m3);
mw0——Content of water per cubic meter of concrete in mix proportion calculation (kg/m3);
m′w0——Content of water per cubic meter of concrete, satisfying actual slump, without chemical admixture addition (kg/m3)
n——Number of test-piece group, larger than or equal to 30;
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;
W/B——Water-binder ratio of concrete;
α——Air content percentage of concrete;
αa, αb——Regression coefficient used in the calculation formula of concrete water-binder ratio;
β——Water reducing ratio of chemical admixture (%);
βa——Addition of chemical admixture (%);
βf——Addition of mineral additive (%);
βs——Ratio of sand to aggregate (%);
γc——Margin coefficient of cement strength grade;
γf——Influence coefficient of fly ash;
γs——Influence coefficient of ground granulated blast furnace slag;
δ——Correction coefficient of concrete mix proportion;
ρc——Density of cement (kg/m3);
ρc, c——Calculated value of concrete mixture apparent density (kg/m3);
ρc, t——Measured value of concrete mixture apparent density (kg/m3);
ρf——Density of mineral additive (kg/m3);
ρg——Apparent density of coarse aggregate (kg/m3);
ρs——Apparent density of fine aggregate (kg/m3);
ρw——Water density (kg/m3);
σ——Standard deviation of concrete strength (MPa).
3 Basic Requirements
3.0.1 Concrete mix proportion design shall meet the design requirements in compounding strength, mechanical property, mixture property, long-term performance and durability. The test methods for concrete mixture property, mechanical property, long-term performance and durability shall respectively meet the requirements of current national standards “Standard for Test Method of Performance on Ordinary Fresh Concrete” GB/T 50080, “Standard for Test Method of Mechanical Properties on Ordinary Fresh Concrete” GB/T 50081 and "Standard for Test Methods of Long-term Performance and Durability of Ordinary Concrete" GB/T 50082.
3.0.2 Material actually used in engineering shall be used in the concrete mix proportion design; and the water ratio of fine aggregate used in mix proportion design shall be less than 0.5%; the water ratio of coarse aggregate shall be less than 0.2%.
3.0.3 Maximum water-cement ratio of concrete shall meet the requirements of current national standard "Code for Design of Concrete Structures" GB 50010.
3.0.4 Except mixing concrete with a strength grade of C15 or lower, minimum binder content of concrete shall meet the requirements specified in Table 3.0.4.
