Ordinary concrete mixing at the scene
1 scope
The technology standard is applicable to industrial and civil construction of common concrete mixing at the scene.
2 construction preparation
2.1 material and main equipments:
2.1.1 cement: the varieties of cement, label, factory don't and the mixing proportion of concrete of the brand should comply with the notice requirements. Cement should have the factory certificate and test report approach.
2.1.2 sand, sand particle size and origin shall comply with the requirements of concrete notice. Silt content in the sand: when the concrete strength grade C30 or silt content 3% or less; < C30 concrete strength grade, the silt content of 5% or less, frost resistance, impermeability requirements, silt content should be 3% or less. In sand soil, the content of pure clay (greater than 5 mm), when the concrete strength grade C30 or higher, the content of soil, should l % or less; < C30 concrete strength grade, the clod content should be 2% or less, frost resistance, impermeability requirements, its soil, content should be l % or less. The sand should have the test report.
2.1.3 stones (gravel and pebbles) : gravel particle size, size distribution and origin of shall comply with the requirements of concrete notice.
Stone needle, flake particle content: when the concrete strength grade C30 or higher, should be 15% or less; When the concrete strength grade is C25 ~ C15, should be 25% or less.
Stones of silt content (less than 0.8 mm of dust, the total content of silt and clay) : when the concrete strength grade C30 or higher, should be 1% or less; When the concrete strength grade is C25 ~ C15, should be 2% or less; When the concrete frost resistance, impermeability requirements, should be 1% or less.
Stone plaster content (greater than 5 mm of pure clay) : when the concrete strength grade C30 or higher, should be 0 5% or less; When the concrete strength grade < C30, should be 0.7% or less. When the concrete strength grade C10 or less, should l % or less.
Stone block report.
2.1.4 water: appropriate USES of drinking water. Other water, the water quality must conform to the "standard of concrete mixing water" (JGJ63 a 89).
2.1.5 admixture, the varieties, manufacturers of concrete admixtures used and the formulations of brand should comply with the notice requirements. Admixtures should have the factory quality certificate and instructions, and shall have the relevant indexes in the test report. Requirements prescribed by the state certification of products, but also should apply certificate. The dosage of admixture must have a test.
2.1.6 hybrid materials (mainly is mixing fly ash, also have the other composite materials, such as UEA expansive agent, zeolite powder, etc.) : the varieties of hybrid materials used, production manufacturers and the formulations of brand should comply with the notice requirements. Hybrid materials should have the factory quality certificate and instructions, and should be in the test report. Material must also be content in the mixture.
2.1.7 major equipment: apply to concrete mixer made preferred forced mixer, can be used in the mixer. The scale or electronic measuring equipment commonly used measuring equipment. Water metering meter can be used, time relay control meter or water tank water level meter. Feeding device has a two-wheeled cart, forklifts, loaders, sandstone lose hopper, etc., and other auxiliary equipment. Field test equipment, test equipment, such as slump test, etc.
2.2 operation conditions:
2.2.1 laboratory has issued notice of concrete with and convert them into every dish of actual use of proportion of construction, and published on the mixing ingredients location sign.
2.2.2 all raw materials through inspection, all should comply with the notice of proportion of the proposed requirements.
2.2.3 mixer and its form a complete set of equipment should be flexible, safe and reliable operation. Power supply and distribution system meets the requirements, safe and reliable.
2.2.4 all measuring instruments must have the validity of the test identification. Loadometer around here and clean up the sand, stone, sensitive and reliable measuring instruments and according to the construction mixture ratio on pounds by designated personnel.
2.2.5 of proportion of management personnel to the operation team, operating rules and safety technical disclosure.
2.2.6 need to be dealt with concrete engineering area has hidden inspection, preview procedures, the concrete application form has the approval of relevant management personnel.
2.2.7 of concrete of new orders, should be to identify the early morning. Early identification of the work and meets the requirements.
3 operation process
3.1 the basic technological process:
3.2 before the start of each affecting, the mixer and feeding equipment for inspection and test run; Inspection on the measuring instruments used and set pounds; Check construction mixture ratio; For raw materials used in specification, type, origin, brand and quality check, and check and construction mixture ratio; Inspection on the moisture content of sand, stone, if there is any change, inform the test personnel to adjust water consumption. All inspection requirements before opening mixing concrete.
3.3 measurement:
3.3.1 sand, stone measurement: use a trolley feeding, must car weighing, discharge is much less. Hopper and form a complete set of measuring equipment, the use of automatic or semi-automatic feeding, need to adjust doumen close people, to ensure accurate measurement. Sand, stone measurement deviation should be allowed + 3% or less.
3.3.2 rainfall distribution on 10-12 measurement: cement mixing when using bagged cement, the cement in the approach of each lot should be random 10 bags of weight, and measure the actual average weight of each bag. To drive less than the calibration of the weight of bag up, or to the actual cement weight of each bag, adjust the dose of sand, stone, water and other materials, according to the mixture ratio of * ratio to determine the proportion of every plate of concrete construction. Stir in the case of bulk cement, should every plate of precise measurement. Cement measurement deviation should be allowed + 2% or less.
3.3.3 admixture and mixture of measurement: the powder admixture and mixture, should according to the construction of each plate material, the admixture and mixture storage warehouse in advance measure, and in small packaging to stir site. Set aside. Liquid admixtures to stir increases with the increasing use and balance to check its concentration, dosage of bucket of measurement. Admixtures, mixture of measurement deviation should be allowed to plus or minus 2% or less.
3.3.4 water metering: must dish measurement, the deviation should be allowed to plus or minus 2% or less.
3.4 feeding: on-site mixing concrete, usually in measure of good raw materials collected in the first hopper, the scripture hopper into the mixing drum. In water and liquid admixture after measurement, to feed in the mixing drum at the same time, directly into the mixing drum. On the collection of raw materials into the hopper of the sequence is as follows:
3.4.1 track when no admixture, mixture, in turn into the hopper of the order for the stone, cement and sand.
3.4.2 when mixing the mixture, the order of gravel, sand, cement, mixture.
Rule 3.4.3 when mixing dry powder admixture, the order for the stone, admixture, cement, sand into the order for gravel, cement, sand and additive.
3.5 the first set of concrete mixing operation:
Every time mixing the first set of concrete work, first add enough water to make the mixing drum idle for several minutes, after mixing barrel is full moisture, pour the remaining water net.
Stir the first set, due to a mortar stick wall loss, therefore, the dosage of the stones should be according to the mixture ratio in half.
Starting from the second set, according to a given mixture feeding.
3.6 mixing time control: concrete mixing the shortest time should be according to table 4 to 28 control.
Concrete mixing in the shortest time (s) table 4 to 28
Mixer out shoes (L)
< 250 > 250 ~ 500, 500
Forced to 60, 90, 120
Since the fall, 90, 120, 150
Forced 60 60, 90
Since the fall, 90, 90, 120
Note: l) the shortest time refers to the concrete mixing, since all materials in mixing drum to stop discharging time to start;
2. When mixed with admixture, stirring time should be extended appropriately;
3. When the winter construction stirring time should be 1.5 times that of the normal temperature mixing time.
3.7 discharge, discharge, first a little discharge, visual appearance quality of mixture, such as visual inspection qualified before discharging. Each plate of concrete mixture must be made.
3.8 concrete mixing quality inspection:
3.8.1 inspection on raw materials used in mixing concrete variety, specifications and usage, each working class at least twice a day.
3.8.2 inspection of concrete slump and workability, each working class at least twice a day. Concrete mixture should stir well, the same color, good liquidity, adhesiveness and water retention, no bleeding, segregation. Should look for reason, is not in conformity with the requirements, timely adjust.
3.8.3 work in each class, when the changes of concrete due to outside influences have (e.g., rain or raw material have change), should be timely to check.
3.8.4 concrete mixing time should check at any time.
3.8.5 according to the following provisions lien block:
3.8.5.1 100 per mixing disc and no more than 100 m3 with mixing proportion of concrete of the sample shall not be less than once a year.
3.8.5.2 each class of concrete mixing with the mixture ratio of less than 100 plate, the sample shall not be less than once a year.
3.8.5.3 of cast-in-situ concrete structure, each cast-in-place floor with the mixture ratio of concrete, the sample shall not be less than once a year.
3.8.5.4 have concrete impermeability requirements, shall be retained by the regulation permeability test block.
Each sampling should be set aside at least a set of standard specimen, with the number set of condition maintenance of specimen to be retained. According to the requirement of technical disclosure. In order to ensure the lien block representative, shall be after the third set to mixing between 30 min before the end of the sampling.
Winter construction of concrete mixing 3.9:
3.9.1 outdoor continuous 5 d stability is lower than the average daily temperature 5 ℃, concrete mixing dong shi measures should be taken, and shall take the temperature drops suddenly anti-freezing measures in a timely manner.
3.9.2 formulate concrete winter construction, should first selection of Portland cement and ordinary Portland cement and cement mark should not be less than 425, minimum dosage of cement should not be less than 300 kg/m3, water cement ratio should not be greater than 0.6.
3.9.3 winter construction without chlorine salt should be used antifreeze, to require high frost resistance of concrete. Appropriate use of air-entraining agent and air-entraining water reducing agent. Such as chlorine salt mixed with antifreeze, should strictly control the dosage, and strictly implement the regulations on chlorine salt mixed with antifreeze.
3.9.4 concrete aggregate used must be clean and shall not contain ice, snow and freezing and frost crack of minerals.
3.9.5 winter mixing concrete should first adopt the method of heating water. Water and the heating temperature aggregate shall be determined according to the computation, but shall not exceed the given in table 4 to 29.
The highest temperature mixing water and aggregate table 4 to 29
Project mixing water bone material
Label size is less than 525 ordinary Portland cement, slag Portland cement 60 ℃ 80 ℃
Label is more than 525 ordinary Portland cement, slag Portland cement 60 ℃ and 40 ℃
Cement shall not directly heated, and should be transported into the greenhouses in storage before use.
When the aggregate is not heated, water can be heated to 100 ℃, the cement should not be direct contact with water of above 80 ℃. Release order first in aggregate and have heated water, and then put into cement.
3.9.6 concrete mixing, hot water or steam washing mixer, mixing time should be take the normal temperature of 1. 5 times. Concrete mixture of temperature should not be below 10 ℃, the machine into the mold temperature is not less than 5 ℃.
3.9.7 winter concrete mixing quality inspection in addition to comply with the provisions of article 3.8, still should make the following checks:
3.9.7.1 check the dosage of admixture.
3.9.7.2 measuring water and additive solution and aggregate the temperature of the heating temperature and join mixer.
3.9.7.3 when measuring the concrete mixer discharge temperature and pouring temperature.
Check every working class shall be measured at least four times.
3.9.7.4 lien of concrete block, besides should comply with the provisions of article 3.8.5 still should add not less than two set of condition maintenance of specimen with structure, respectively used to verify that the concrete strength and before the cold into a room temperature curing 28 d strength of concrete.
4 quality standards
4.1 ensure projects:
4.4.1 concrete used in cement, aggregate, admixture, mixture of specifications, varieties and quality must comply with the provisions of the relevant standards.
Inspection method: inspect raw materials factory certificate and test report.
4.1.2 the strength of the concrete evaluation should comply with the requirements.
Inspection methods: inspection of concrete block strength test report and strength assessment data.
4.2 the basic items:
2 should mix concrete, consistent color, good workability.
Inspection method: to observe the examination.
4.2.2 the slump of concrete mixture should comply with the requirements.
Inspection methods: field testing and checking construction records.
Holdings winter construction, the heating temperature of water, aggregate and concrete mixture out of the machine temperature should comply with the requirements.
Inspection methods: field testing and checking construction records.
5 quality problems should be paid attention to
5.1 strength of concrete strength is insufficient or uneven, the intensity of deviation is large, is often happened quality problem, is the quality problem of the structure safety. To prevent this quality problem requires a comprehensive treatment, in addition to transportation, pouring and curing of concrete shall strictly control the each link, pay special attention in concrete mixing phase. To control the quality of all kinds of materials. To seriously implement the mixture ratio, strict raw material ingredients measurement.
5.2 the quality problem of the concrete crack is often occur. For many reasons. In mixing stage, if the silt sand, stone, water consumption, the use of outdated cement or cement dosage too much and so on, is likely to be caused by concrete shrinkage crack. So in mixing stage, still need to strictly control the quality of raw materials, carefully implement the mixture ratio, strict measurement.
5.3 the poor mixture workability of concrete, slump does not conform to the requirements. There are many reasons for this kind of quality problem. The biggest influence of water-cement ratio; The second is gravel gradation is poor, needle, flake particle content is too much; The third is the stirring time is too short or too long to wait. The solution from the above three aspects.
5.4 winter concrete construction prone to frost damage. The solution is to conscientiously implement the relevant provisions of the dong shi, in mixing phase aggregate and water heating temperature, assure the temperatures of coagulation factory of the machine.
5.5 to pay attention to the storage of cement, admixture, mixture. Cement should be cement silo, prevent the rain and be affected with damp be affected with damp; The cement in the factory for more than three months should be a second interview. To prevent be affected with damp be affected with damp and metamorphism, admixture, mixture to specifications, variety store, respectively, in order to prevent misuse.
6 quality records
This technology standard should have the following quality records:
6.1 the cement factory quality certification.
6.2 cement in test report.
6.3 additive factory quality certification.
Dosage of 6.4 admixture in the test report and test report.
6.5 mixture factory quality certification.
6.6 dosage of mixture in the test report and test report.
6.7 the sand test report.
6.8 stone test report.
6.9 concrete of notice.
6.10 concrete block strength test report.
6.11 concrete strength evaluation records.
6.12 concrete construction log (including winter logs).
6.13 concrete early identification.
1 scope
The technology standard is applicable to industrial and civil construction of common concrete mixing at the scene.
2 construction preparation
2.1 material and main equipments:
2.1.1 cement: the varieties of cement, label, factory don't and the mixing proportion of concrete of the brand should comply with the notice requirements. Cement should have the factory certificate and test report approach.
2.1.2 sand, sand particle size and origin shall comply with the requirements of concrete notice. Silt content in the sand: when the concrete strength grade C30 or silt content 3% or less; < C30 concrete strength grade, the silt content of 5% or less, frost resistance, impermeability requirements, silt content should be 3% or less. In sand soil, the content of pure clay (greater than 5 mm), when the concrete strength grade C30 or higher, the content of soil, should l % or less; < C30 concrete strength grade, the clod content should be 2% or less, frost resistance, impermeability requirements, its soil, content should be l % or less. The sand should have the test report.
2.1.3 stones (gravel and pebbles) : gravel particle size, size distribution and origin of shall comply with the requirements of concrete notice.
Stone needle, flake particle content: when the concrete strength grade C30 or higher, should be 15% or less; When the concrete strength grade is C25 ~ C15, should be 25% or less.
Stones of silt content (less than 0.8 mm of dust, the total content of silt and clay) : when the concrete strength grade C30 or higher, should be 1% or less; When the concrete strength grade is C25 ~ C15, should be 2% or less; When the concrete frost resistance, impermeability requirements, should be 1% or less.
Stone plaster content (greater than 5 mm of pure clay) : when the concrete strength grade C30 or higher, should be 0 5% or less; When the concrete strength grade < C30, should be 0.7% or less. When the concrete strength grade C10 or less, should l % or less.
Stone block report.
2.1.4 water: appropriate USES of drinking water. Other water, the water quality must conform to the "standard of concrete mixing water" (JGJ63 a 89).
2.1.5 admixture, the varieties, manufacturers of concrete admixtures used and the formulations of brand should comply with the notice requirements. Admixtures should have the factory quality certificate and instructions, and shall have the relevant indexes in the test report. Requirements prescribed by the state certification of products, but also should apply certificate. The dosage of admixture must have a test.
2.1.6 hybrid materials (mainly is mixing fly ash, also have the other composite materials, such as UEA expansive agent, zeolite powder, etc.) : the varieties of hybrid materials used, production manufacturers and the formulations of brand should comply with the notice requirements. Hybrid materials should have the factory quality certificate and instructions, and should be in the test report. Material must also be content in the mixture.
2.1.7 major equipment: apply to concrete mixer made preferred forced mixer, can be used in the mixer. The scale or electronic measuring equipment commonly used measuring equipment. Water metering meter can be used, time relay control meter or water tank water level meter. Feeding device has a two-wheeled cart, forklifts, loaders, sandstone lose hopper, etc., and other auxiliary equipment. Field test equipment, test equipment, such as slump test, etc.
2.2 operation conditions:
2.2.1 laboratory has issued notice of concrete with and convert them into every dish of actual use of proportion of construction, and published on the mixing ingredients location sign.
2.2.2 all raw materials through inspection, all should comply with the notice of proportion of the proposed requirements.
2.2.3 mixer and its form a complete set of equipment should be flexible, safe and reliable operation. Power supply and distribution system meets the requirements, safe and reliable.
2.2.4 all measuring instruments must have the validity of the test identification. Loadometer around here and clean up the sand, stone, sensitive and reliable measuring instruments and according to the construction mixture ratio on pounds by designated personnel.
2.2.5 of proportion of management personnel to the operation team, operating rules and safety technical disclosure.
2.2.6 need to be dealt with concrete engineering area has hidden inspection, preview procedures, the concrete application form has the approval of relevant management personnel.
2.2.7 of concrete of new orders, should be to identify the early morning. Early identification of the work and meets the requirements.
3 operation process
3.1 the basic technological process:
3.2 before the start of each affecting, the mixer and feeding equipment for inspection and test run; Inspection on the measuring instruments used and set pounds; Check construction mixture ratio; For raw materials used in specification, type, origin, brand and quality check, and check and construction mixture ratio; Inspection on the moisture content of sand, stone, if there is any change, inform the test personnel to adjust water consumption. All inspection requirements before opening mixing concrete.
3.3 measurement:
3.3.1 sand, stone measurement: use a trolley feeding, must car weighing, discharge is much less. Hopper and form a complete set of measuring equipment, the use of automatic or semi-automatic feeding, need to adjust doumen close people, to ensure accurate measurement. Sand, stone measurement deviation should be allowed + 3% or less.
3.3.2 rainfall distribution on 10-12 measurement: cement mixing when using bagged cement, the cement in the approach of each lot should be random 10 bags of weight, and measure the actual average weight of each bag. To drive less than the calibration of the weight of bag up, or to the actual cement weight of each bag, adjust the dose of sand, stone, water and other materials, according to the mixture ratio of * ratio to determine the proportion of every plate of concrete construction. Stir in the case of bulk cement, should every plate of precise measurement. Cement measurement deviation should be allowed + 2% or less.
3.3.3 admixture and mixture of measurement: the powder admixture and mixture, should according to the construction of each plate material, the admixture and mixture storage warehouse in advance measure, and in small packaging to stir site. Set aside. Liquid admixtures to stir increases with the increasing use and balance to check its concentration, dosage of bucket of measurement. Admixtures, mixture of measurement deviation should be allowed to plus or minus 2% or less.
3.3.4 water metering: must dish measurement, the deviation should be allowed to plus or minus 2% or less.
3.4 feeding: on-site mixing concrete, usually in measure of good raw materials collected in the first hopper, the scripture hopper into the mixing drum. In water and liquid admixture after measurement, to feed in the mixing drum at the same time, directly into the mixing drum. On the collection of raw materials into the hopper of the sequence is as follows:
3.4.1 track when no admixture, mixture, in turn into the hopper of the order for the stone, cement and sand.
3.4.2 when mixing the mixture, the order of gravel, sand, cement, mixture.
Rule 3.4.3 when mixing dry powder admixture, the order for the stone, admixture, cement, sand into the order for gravel, cement, sand and additive.
3.5 the first set of concrete mixing operation:
Every time mixing the first set of concrete work, first add enough water to make the mixing drum idle for several minutes, after mixing barrel is full moisture, pour the remaining water net.
Stir the first set, due to a mortar stick wall loss, therefore, the dosage of the stones should be according to the mixture ratio in half.
Starting from the second set, according to a given mixture feeding.
3.6 mixing time control: concrete mixing the shortest time should be according to table 4 to 28 control.
Concrete mixing in the shortest time (s) table 4 to 28
Mixer out shoes (L)
< 250 > 250 ~ 500, 500
Forced to 60, 90, 120
Since the fall, 90, 120, 150
Forced 60 60, 90
Since the fall, 90, 90, 120
Note: l) the shortest time refers to the concrete mixing, since all materials in mixing drum to stop discharging time to start;
2. When mixed with admixture, stirring time should be extended appropriately;
3. When the winter construction stirring time should be 1.5 times that of the normal temperature mixing time.
3.7 discharge, discharge, first a little discharge, visual appearance quality of mixture, such as visual inspection qualified before discharging. Each plate of concrete mixture must be made.
3.8 concrete mixing quality inspection:
3.8.1 inspection on raw materials used in mixing concrete variety, specifications and usage, each working class at least twice a day.
3.8.2 inspection of concrete slump and workability, each working class at least twice a day. Concrete mixture should stir well, the same color, good liquidity, adhesiveness and water retention, no bleeding, segregation. Should look for reason, is not in conformity with the requirements, timely adjust.
3.8.3 work in each class, when the changes of concrete due to outside influences have (e.g., rain or raw material have change), should be timely to check.
3.8.4 concrete mixing time should check at any time.
3.8.5 according to the following provisions lien block:
3.8.5.1 100 per mixing disc and no more than 100 m3 with mixing proportion of concrete of the sample shall not be less than once a year.
3.8.5.2 each class of concrete mixing with the mixture ratio of less than 100 plate, the sample shall not be less than once a year.
3.8.5.3 of cast-in-situ concrete structure, each cast-in-place floor with the mixture ratio of concrete, the sample shall not be less than once a year.
3.8.5.4 have concrete impermeability requirements, shall be retained by the regulation permeability test block.
Each sampling should be set aside at least a set of standard specimen, with the number set of condition maintenance of specimen to be retained. According to the requirement of technical disclosure. In order to ensure the lien block representative, shall be after the third set to mixing between 30 min before the end of the sampling.
Winter construction of concrete mixing 3.9:
3.9.1 outdoor continuous 5 d stability is lower than the average daily temperature 5 ℃, concrete mixing dong shi measures should be taken, and shall take the temperature drops suddenly anti-freezing measures in a timely manner.
3.9.2 formulate concrete winter construction, should first selection of Portland cement and ordinary Portland cement and cement mark should not be less than 425, minimum dosage of cement should not be less than 300 kg/m3, water cement ratio should not be greater than 0.6.
3.9.3 winter construction without chlorine salt should be used antifreeze, to require high frost resistance of concrete. Appropriate use of air-entraining agent and air-entraining water reducing agent. Such as chlorine salt mixed with antifreeze, should strictly control the dosage, and strictly implement the regulations on chlorine salt mixed with antifreeze.
3.9.4 concrete aggregate used must be clean and shall not contain ice, snow and freezing and frost crack of minerals.
3.9.5 winter mixing concrete should first adopt the method of heating water. Water and the heating temperature aggregate shall be determined according to the computation, but shall not exceed the given in table 4 to 29.
The highest temperature mixing water and aggregate table 4 to 29
Project mixing water bone material
Label size is less than 525 ordinary Portland cement, slag Portland cement 60 ℃ 80 ℃
Label is more than 525 ordinary Portland cement, slag Portland cement 60 ℃ and 40 ℃
Cement shall not directly heated, and should be transported into the greenhouses in storage before use.
When the aggregate is not heated, water can be heated to 100 ℃, the cement should not be direct contact with water of above 80 ℃. Release order first in aggregate and have heated water, and then put into cement.
3.9.6 concrete mixing, hot water or steam washing mixer, mixing time should be take the normal temperature of 1. 5 times. Concrete mixture of temperature should not be below 10 ℃, the machine into the mold temperature is not less than 5 ℃.
3.9.7 winter concrete mixing quality inspection in addition to comply with the provisions of article 3.8, still should make the following checks:
3.9.7.1 check the dosage of admixture.
3.9.7.2 measuring water and additive solution and aggregate the temperature of the heating temperature and join mixer.
3.9.7.3 when measuring the concrete mixer discharge temperature and pouring temperature.
Check every working class shall be measured at least four times.
3.9.7.4 lien of concrete block, besides should comply with the provisions of article 3.8.5 still should add not less than two set of condition maintenance of specimen with structure, respectively used to verify that the concrete strength and before the cold into a room temperature curing 28 d strength of concrete.
4 quality standards
4.1 ensure projects:
4.4.1 concrete used in cement, aggregate, admixture, mixture of specifications, varieties and quality must comply with the provisions of the relevant standards.
Inspection method: inspect raw materials factory certificate and test report.
4.1.2 the strength of the concrete evaluation should comply with the requirements.
Inspection methods: inspection of concrete block strength test report and strength assessment data.
4.2 the basic items:
2 should mix concrete, consistent color, good workability.
Inspection method: to observe the examination.
4.2.2 the slump of concrete mixture should comply with the requirements.
Inspection methods: field testing and checking construction records.
Holdings winter construction, the heating temperature of water, aggregate and concrete mixture out of the machine temperature should comply with the requirements.
Inspection methods: field testing and checking construction records.
5 quality problems should be paid attention to
5.1 strength of concrete strength is insufficient or uneven, the intensity of deviation is large, is often happened quality problem, is the quality problem of the structure safety. To prevent this quality problem requires a comprehensive treatment, in addition to transportation, pouring and curing of concrete shall strictly control the each link, pay special attention in concrete mixing phase. To control the quality of all kinds of materials. To seriously implement the mixture ratio, strict raw material ingredients measurement.
5.2 the quality problem of the concrete crack is often occur. For many reasons. In mixing stage, if the silt sand, stone, water consumption, the use of outdated cement or cement dosage too much and so on, is likely to be caused by concrete shrinkage crack. So in mixing stage, still need to strictly control the quality of raw materials, carefully implement the mixture ratio, strict measurement.
5.3 the poor mixture workability of concrete, slump does not conform to the requirements. There are many reasons for this kind of quality problem. The biggest influence of water-cement ratio; The second is gravel gradation is poor, needle, flake particle content is too much; The third is the stirring time is too short or too long to wait. The solution from the above three aspects.
5.4 winter concrete construction prone to frost damage. The solution is to conscientiously implement the relevant provisions of the dong shi, in mixing phase aggregate and water heating temperature, assure the temperatures of coagulation factory of the machine.
5.5 to pay attention to the storage of cement, admixture, mixture. Cement should be cement silo, prevent the rain and be affected with damp be affected with damp; The cement in the factory for more than three months should be a second interview. To prevent be affected with damp be affected with damp and metamorphism, admixture, mixture to specifications, variety store, respectively, in order to prevent misuse.
6 quality records
This technology standard should have the following quality records:
6.1 the cement factory quality certification.
6.2 cement in test report.
6.3 additive factory quality certification.
Dosage of 6.4 admixture in the test report and test report.
6.5 mixture factory quality certification.
6.6 dosage of mixture in the test report and test report.
6.7 the sand test report.
6.8 stone test report.
6.9 concrete of notice.
6.10 concrete block strength test report.
6.11 concrete strength evaluation records.
6.12 concrete construction log (including winter logs).
6.13 concrete early identification.
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