The 1.1 varieties of cement and the strength grade should be determined according to the environment design, construction requirements and engineering. For ordinary concrete building structures and precast, should adopt the common portland cement; high strength concrete and frost resistance of concrete requirements should be used in Portland cement or ordinary portland cement; concrete engineering requirements to prevent the alkali aggregate reaction in concrete should be used less than 0.6% alkali content of cement; mass concrete Medium and low heat Portland cement or low heat slag Portland cement should be adopted. The cement should be consistent with current national standard "general" and "Portland cement GB175 heat Portland cement low heat Portland cement Portland slag cement", the relevant provisions of GB 0.
The 1.2 main control items should include the quality of the cement setting time and soundness and strength of cement mortar, Magnesium Oxide and chloride ion content, alkali content of less than 0.6% of the cement main control projects should also include the content of alkali, and low heat Portland cement and Portland slag cement main control project should also include the heat of hydration.
1.3 the application of cement should meet the following requirements:
1 it is advisable to adopt cement produced by new dry process kiln.
2 the varieties and dosage of mixed cement should be specified.
3 the temperature of cement produced by hand should not be higher than sO C.
2.2 coarse aggregate
2.1 coarse aggregates shall meet the requirements of the current industry standard "standard" for ordinary concrete sand, stone quality and test method of JGJ52.
2.2 coarse aggregate quality of the main control items should include particle size, elongated particle content, clay content, clay content, crush value index and robustness for high strength concrete coarse aggregate King's main control projects should also include the compressive strength of rock.
2.3 the application of coarse aggregate should meet the following requirements:
1 concrete coarse aggregate should be continuously graded.
2 for concrete structure, coarse aggregate nominal maximum size should not be greater than the minimum size of the 1/4 section, and shall not be greater than the minimum spacing of 3/4 reinforced concrete; the solid board, the aggregate nominal maximum size of not more than 1/3 thick plate, and shall not be greater than that of mm; for large volume concrete, coarse aggregate nominal maximum particle the diameter of not less than 31. 5mm.
3 for the impermeability, frost resistance, corrosion resistance, abrasion resistance or other special requirements of the coarse aggregate in concrete, clay content and clay content should not be greater than 1% and 0.5% respectively; solid mass loss test should not be greater than 8%.
4 for the high bridge concrete, rock compressive strength of coarse aggregate should be better than the design strength of concrete with high 30%; the maximum nominal size of not more than 25rrun, elongated particles should not be greater than 5% and should not be greater than 8%; amount of mud and mud content should not be greater than 0.5% and 0.2% respectively.
5 of coarse aggregate or for the production of coarse aggregate rock should be alkaline activity test, including the alkali silica reaction test and alkali carbonate reactivity test; opponents have concrete engineering requirements prevent concrete alkali aggregate reaction, should not be used for coarse aggregate alkali activity.
.3 fine aggregate
3.1 fine aggregate shall meet the requirements of the standard for "dish standard" for ordinary concrete sand, stone quality and test method of JGJ52; concrete sand should be consistent with current industry standard "technical specifications" JGJ sea sand concrete application, the relevant provisions of the 6.
3.2 fine aggregate quality control items should include particle size, fineness modulus 1 clay content, clay content, firmness, chloride content and the content of harmful substances; the main sand control project in addition to including these indicators should be included in the main shell; artificial sand control project in addition to including these indicators should be included powder The content and the crushing value refers to the strict, artificial sand control project can not Cui Feng GUI including chlorine ion content and the content of harmful substances.
3.3 the application of fine aggregate should meet the following requirements:
1 medium sand is suitable for pumping concrete, and the particle throughput of 300um sieve hole should not be less than 15%. 2 for the anti permeability and anti freeze or other special requirements of concrete, sand in the mud and mud content should not be greater than 3% and 1% respectively; solid mass loss test should not be greater than 8%.
3 for high strength concrete, fineness modulus of sand should be controlled within the range of 0 2.6~ 3, mud content and clay content should not be greater than 2% and 0.5% respectively.
4 the chloride content of sand for reinforced concrete and prestressed concrete should not be greater than 0.06% and 0 respectively. Infinity%.
5 sea sand used for concrete should be purified.
6 the chloride content of sea sand used in concrete should not exceed 0.03%, and shell content should conform to table 2.3.3 Delta. Sea sand shall not be used for prestressed concrete.
7 the content of stone powder in manufactured sand should comply with the regulations of table 2.3.3 Torr. Table 2.3. (2) stone powder contained in artificial sand contains No. 2 (%).
8 it is not suitable to use extra fine sand as fine aggregate to make concrete.
The 9 river sand and sea sand should be alkali-silica reaction activity test; artificial sand should be alkali silica reaction test and alkali carbonate reactivity test; for the prevention of alkali aggregate reaction in concrete requirements of the project, should not adopt the alkali reactivity of sand.