Lightweight aggregate concrete mixing at the scene
1 scope
This technology standard rules on the lightweight aggregate concrete mixing construction site preparation, operation process, quality standard and quality acceptance and so on.
The technology standard is applicable to industrial and civil construction of lightweight aggregate 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 in color.
2.1.2 sand, sand particle size and origin shall comply with the requirements of concrete notice. In the sand silt content; When the concrete strength grade C30 or higher, the silt content should be 3% or less; < C30 concrete strength grade, the silt content should be 5% or less. Sand content of soil in pure clay (greater than 5 mm) : when the concrete strength grade C30 or higher, should be < 1%; < C30 concrete strength grade, should be 2% or less. The sand should have the test report.
2.1.3 light weight aggregate: light weight aggregate (ceramsite or pumice, etc.) the variety, size, origin shall comply with the requirements of concrete notice. Light weight aggregate should be the factory quality certificate and test report approach. Must test the project are: weight aggregate sieve analysis test; Thickness of aggregate packing density; Coarse aggregate cylinder compressive strength; The aggregate water absorption test.
Light of coarse aggregate gradation meets the requirements of table 4-30, its natural distribution of void fraction should not be greater than 50%. Its biggest particle size should not be greater than 20 mm. The silt content is not more than 2%.
Light of coarse gradation table 4-30
Mesh size dmin (5) 1/2 (10) (20) 2 on3dmax on3dmax on3dmax (2 x 20)
Globe and single graded cumulative triage acuity 90 not regulation 10 0 or less
The mixture of normal grading by weight meter 90 30 ~ 70 10 0 or less or more
Type of gravel mixture gradation (%) of 90 or more 40 ~ 60 10 0 or less
Light sand fineness modulus should not be greater than 4.0, and its greater than 5 mm sieve room should not be greater than 10% (by weight).
The bulk density of light weight aggregate, lightweight aggregate of cylinder pressure strength and the strength grade should meet the design requirements.
Light and natural light the bibulous rate of coarse aggregate; Other light aggregate the bibulous rate of 1 h is not greater than 22%.
2.1.4 water: appropriate USES of drinking water. Other water quality must conform to the "standard of concrete mixing water" (JGJ63 a 89).
2.1.5 admixture; Manufacturer of the lightweight aggregate concrete admixtures used varieties, 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 indicators into the factory 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) : the varieties of hybrid materials used, production manufacturers and the ratio 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 be content in the mixture.
2.1.7 major equipment: light sand concrete should be preferred forced mixer, also using the mixer. All light concrete should be forced 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 such as a two-wheeled cart, forklifts, loaders, coarse and fine aggregate hopper and other equipment. Field test equipment, test equipment, such as slump test, etc.
2.2 operation conditions:
2.2.1 laboratory has issued a notice of lightweight aggregate concrete mixing ratio, and transform it into every dish of actual use of proportion of construction, and published on the mixing ingredients location sign.
2.2.2 raw materials used in the tests, all should comply with the notice of proportion of the proposed requirements.
2.2.3 mixer and its form a complete set of equipment operation flexible, safe and reliable. 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 casting engineering parts of lightweight aggregate concrete has hidden inspection, preview formalities, lightweight aggregate concrete application form has the approval of relevant management personnel.
2.2.7 issued new light weight aggregate concrete mix proportion, 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:
Production of lightweight aggregate concrete basic process flow diagram
3.2 stacking and storage of raw materials:
3.2.1 light should be according to the grade of the aggregate pile up, and shall have the waterproof and drainage measures, in order to prevent moisture content changes. Mixture fraction stacked, stacking height should not be commonly more than 2 m, in case the size of particles segregation, uneven distribution. When mixed with ordinary aggregate used, should make the weight aggregate storage respectively, it is forbidden to mix, to guarantee the accuracy of the ingredients.
3.2.2 cement, admixture, additive should be put in storage, waterproof, moisture-proof warehouse in order to prevent the cement scleroma, admixture moisture content change, powdered admixture failure, fluid additive concentration changes.
3.3 raw materials measurement and sampling measurement:
3.3.1 light weight aggregate measurement: appropriate USES volume metering, also USES the weight measurement, but it must be strictly test the moisture content of aggregate, remove outside its moisture content, the weight of the water to guarantee the accuracy of the ingredients. Ordinary sand by weight. When volume metering, must use the special measuring carts or dedicated volume meter, every dish we will strictly measurement.
When using weight measurement, the use of carts, must car weighing, discharge is much less. Has the hopper and the measuring equipment of form a complete set, using automatic or semi-automatic feeding, need to adjust the doumen switch of schedule, to ensure accurate measurement.
Light weight aggregate metering the allowable deviation of plus or minus 3% or less.
3.3.2 rainfall distribution on 10-12 cement measurement: using bagged cement, must according to purchase batch of random sampling measurement. General approach of each lot of cement should be random 10 bags of weight, and calculate the average actual weight of each bag. Is less than the calibration weight to make up the bag is opened, or will be subject to the actual weight of each bag of cement, adjust the thickness of aggregate, the amount of water and other material, according to a given to determine each coil construction mix proportioning. When using bulk cement, should every dish precision weighing measurement. Cement measurement deviation should be allowed + 2% or less.
3.3.3 admixture and mixture of measurement: bags powdered admixture and mixture, should according to each batch in selectiving examination 10 bags of weight, and measuring average weight for each bag, to make up less than the calibration weight. For bulk or large packaging admixture, should according to the construction of each dish dosage is measured in advance in its place, and in the form of a small package to stir site. Set aside. Liquid admixtures to stir increases with the increasing use and balance to check its concentration, measured with a measuring cylinder. Additives and the mixture of measurement deviation should be allowed to plus or minus 2% or less.
3.3.4 mixing water must dish measuring flow meter reading, or use the water tank water level tube mark meter. Its every dish allow deviation plus or minus 2% or less.
3.4 light weight aggregate concrete mixing charge process of:
3.4.1 track lightweight aggregate concrete mixing, bibulous rate is less than 10% appropriate USES secondary feeding process. Will be put into blender with 1/2 weight aggregate water mixing about 1 min, first add the cement mixing a few seconds, and then add the remaining water and admixtures, and continue to stir until 2 min, the method of feeding and mixing process diagram are:
Half the total water consumption
The aggregate 1/2 total water use, water mud additive
Mixing water and aggregate mixture mixing of concrete mixture
Fine aggregate
Lightweight aggregate bibulous rate is greater than 10% of the concrete mixing, appropriate USES prewetting aggregate feeding and mixing process. The general light aggregate prewetting before mixing, according to the order of the coarse aggregate, cement, fine aggregate into blender summary, to be put in a blender mixing barrel 0.5 min dry mixing, and then with water and admixture mixing 2.5 min, the method of feeding and mixing process diagram are:
Water and coarse aggregate net water admixtures
Water compote stirring mixing concrete mixture
Fine aggregate
Rule 3.4.3 adopted since the fall of the mixer feeding and mixing process is: first add 1/2 of the total amount of water, then add the thickness of aggregate and cement mixing lmin, plus surplus water continued to stir 2 min, the method of feeding and mixing process diagram are:
1/2 of the aggregate total water consumption total water use 1/2
Water stirring mixing mud mixture mixed concrete mixture
Fine aggregate
3.4.4 using forced mixer feeding and mixing process is: first cast of coarse aggregate, cement, fine aggregate, mixing lmin, then add water to mixing of not less than 2 min. The method of feeding and mixing process diagram are:
The aggregate total water use admixtures
Water compote stir stir the mixture mixing of concrete mixture
Fine aggregate
3.5 the first set mixing concrete problems that should be paid attention to:
3.5 l before mixing concrete, adding water idle for several minutes, after being churn fully wetting, will more than water is clean.
3.5.2 first plate of mixing concrete, cement mortar to stick wall mixture ratio. Take pre mixing method, namely the use of lightweight aggregate concrete mixture ratio design of a given first put into blender mixing raw materials, the time must be more than double, to be part of the mortar paste on the mixer are compared.in addition, then the rest of the discharged mixture (secondary feed mixing reoccupy), then the normal mixing can be performed.
3.6 mixing time control and inspection: made of lightweight aggregate concrete mixing the shortest time, than ordinary concrete mixing time should be extended to 60 ~ 90 s, general for the 180 s; When mixed with admixture, stirring time should be extended appropriately.
Discharge: 3.7 should be a little out of material, visual appearance quality of mixture, such as visual inspection qualified before discharging. Each coil must be out of the mixture.
3.8 light weight aggregate concrete mixing quality inspection:
3.8.1 check of lightweight aggregate concrete mixing raw materials used in varieties, specifications and usage, each working class at least twice a day. The rain period construction, to increase the water content of lightweight aggregate inspection and measurement.
3.8.2 check in pouring location of lightweight aggregate concrete slump and workability, each class more than two times. Stage rain, winter construction and a change in grade of lightweight aggregate concrete, to enhance the number of detection.
3.8.3 within each class, when light weight aggregate concrete mixture ratio due to outside influences have change, should check in time.
3.8.4 lightweight aggregate concrete mixing time should check at any time.
3.8.5 check appearance quality should be a mixture of lightweight aggregate concrete, stir well, consistent color, good liquidity, adhesiveness and water retention, no bleeding, no segregation. Do not conform to the requirements, should check the reason, adjust in time.
3.8.6 according to the following provisions lien block:
3.8.6.1 100 per mixing disc and no more than 100 m3 with mixing proportion of concrete, the sample shall not be less than once a year.
3.8.6.2 each class of concrete mixing with the mixture ratio of less than 100 plate, the sample shall not be less than once a year.
3.8.6.3 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.
3.8.6.4 each sampling should be at least a set of standard specimen, lien with number groups of condition maintenance of specimen to be retained, according to the requirement of technical disclosure.
In order to ensure the representative block, lien should be before the end of the third set to after mixing concrete mixing sampling between 30 min.
Winter construction of lightweight aggregate concrete mixing: 3.9 during that time, demand for raw materials, mixing time, raw material, heating, mixture out of the pot temperature requirements, etc., should be seriously implemented "standard of ordinary concrete mixing process on site" in article 3.9 and the concrete structure engineering construction and acceptance standard ".
3.9.1 weight aggregate shall not contain ice and snow and frozen clumps.
3.9.2 winter appropriate USES the secondary feeding of lightweight aggregate concrete mixing, secondary mixing process (see rule 3.4 l of the mixing process), in order to improve the workability of lightweight aggregate concrete.
3.9.3 winter should pay attention to test the moisture content of aggregate, timely adjust the water consumption, given slump different components in a timely manner. Than normal temperature slump increases commonly 4 to 6 cm, to ensure that it has good liquidity, adhesiveness and water retention.
4 quality standards
4.1 ensure projects:
4.4.1 lightweight aggregate concrete used in the cement, aggregate, admixture, mixture specifications and varieties and must be in conformity with the relevant provisions of the construction specification and quality.
Inspection method: inspect raw materials factory certificate and test report.
4.2.2 assess the strength of lightweight aggregate concrete block, must according to the concrete strength inspection criteria (GBJ107 87) sample making.
Inspection method: check the strength of lightweight aggregate concrete block test reports and strength assessment information.
4.2 the basic items:
2 should mix of lightweight aggregate concrete, consistent color, good workability.
Inspection methods; Observe check.
4.2.2 of lightweight aggregate concrete mixture slump should accord with the requirement of construction specifications or their mixture ratio notice.
Inspection methods: field testing and checking construction records.
Holdings in construction of winter water, the heating temperature of aggregate and concrete mixture out of the pot temperature should accord with the requirement of construction specifications.
Inspection methods: field testing and checking construction records.
5 quality problems should be paid attention to
5.1 stir the mixture not divide evenly. Color is not consistent: the main reason is the insufficient mixing time.
Particularly to ensure that the winter construction and add the additive, enough time to stir the mixture.
5.2 poor workability, its produce loose mixture is not sticking together and aggregate segregation, floating or mixture to form a mass of unfavorable casting. The main reason is: lightweight aggregate gradation is poor; Sand ratio is too small; Raw materials inaccurate measurement; Or short mixing time. Should overcome the defect carefully, in order to guarantee the good workability of mixture.
5.3 mixture slump is not stable. Master is not accurate, the main reason is that water thickness determination of the change of moisture content in aggregate not promptly, failed to timely adjust the water consumption. Followed by water measurement is not accurate, much less dosage of water. This phenomenon must be overcome to ensure the immanent quality of mixture.
5.4 when using admixture, appropriate in aggregate after absorbing water. To avoid excessive aggregate pore of admixture of absorption. Especially liquid admixtures, use prewetting aggregate, admixture should join with residual water at the same time. Join powder admixture can be made into liquid according to the former method, can also be mixture with cement to join at the same time, to ensure the uniform mixing.
6 quality records
This technology standard should have the following quality records:
6.1 cement factory certification or test certification.
6.2 cement second-round exam list.
6.3 the sand test report.
6.4 light fine aggregate test report.
6.5 light aggregate test report.
6.6 additive product certificate and the certificate of quality.
Dosage of 6.7 admixture in the test report and test report.
6.8 gap of fly ash bricks.
6.9 test report of fly ash.
6.10 concrete of notice.
6.11 concrete construction log (including winter logs).
6.12 concrete early identification.
6.13 concrete block strength test report.
6.14 concrete strength evaluation records.
1 scope
This technology standard rules on the lightweight aggregate concrete mixing construction site preparation, operation process, quality standard and quality acceptance and so on.
The technology standard is applicable to industrial and civil construction of lightweight aggregate 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 in color.
2.1.2 sand, sand particle size and origin shall comply with the requirements of concrete notice. In the sand silt content; When the concrete strength grade C30 or higher, the silt content should be 3% or less; < C30 concrete strength grade, the silt content should be 5% or less. Sand content of soil in pure clay (greater than 5 mm) : when the concrete strength grade C30 or higher, should be < 1%; < C30 concrete strength grade, should be 2% or less. The sand should have the test report.
2.1.3 light weight aggregate: light weight aggregate (ceramsite or pumice, etc.) the variety, size, origin shall comply with the requirements of concrete notice. Light weight aggregate should be the factory quality certificate and test report approach. Must test the project are: weight aggregate sieve analysis test; Thickness of aggregate packing density; Coarse aggregate cylinder compressive strength; The aggregate water absorption test.
Light of coarse aggregate gradation meets the requirements of table 4-30, its natural distribution of void fraction should not be greater than 50%. Its biggest particle size should not be greater than 20 mm. The silt content is not more than 2%.
Light of coarse gradation table 4-30
Mesh size dmin (5) 1/2 (10) (20) 2 on3dmax on3dmax on3dmax (2 x 20)
Globe and single graded cumulative triage acuity 90 not regulation 10 0 or less
The mixture of normal grading by weight meter 90 30 ~ 70 10 0 or less or more
Type of gravel mixture gradation (%) of 90 or more 40 ~ 60 10 0 or less
Light sand fineness modulus should not be greater than 4.0, and its greater than 5 mm sieve room should not be greater than 10% (by weight).
The bulk density of light weight aggregate, lightweight aggregate of cylinder pressure strength and the strength grade should meet the design requirements.
Light and natural light the bibulous rate of coarse aggregate; Other light aggregate the bibulous rate of 1 h is not greater than 22%.
2.1.4 water: appropriate USES of drinking water. Other water quality must conform to the "standard of concrete mixing water" (JGJ63 a 89).
2.1.5 admixture; Manufacturer of the lightweight aggregate concrete admixtures used varieties, 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 indicators into the factory 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) : the varieties of hybrid materials used, production manufacturers and the ratio 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 be content in the mixture.
2.1.7 major equipment: light sand concrete should be preferred forced mixer, also using the mixer. All light concrete should be forced 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 such as a two-wheeled cart, forklifts, loaders, coarse and fine aggregate hopper and other equipment. Field test equipment, test equipment, such as slump test, etc.
2.2 operation conditions:
2.2.1 laboratory has issued a notice of lightweight aggregate concrete mixing ratio, and transform it into every dish of actual use of proportion of construction, and published on the mixing ingredients location sign.
2.2.2 raw materials used in the tests, all should comply with the notice of proportion of the proposed requirements.
2.2.3 mixer and its form a complete set of equipment operation flexible, safe and reliable. 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 casting engineering parts of lightweight aggregate concrete has hidden inspection, preview formalities, lightweight aggregate concrete application form has the approval of relevant management personnel.
2.2.7 issued new light weight aggregate concrete mix proportion, 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:
Production of lightweight aggregate concrete basic process flow diagram
3.2 stacking and storage of raw materials:
3.2.1 light should be according to the grade of the aggregate pile up, and shall have the waterproof and drainage measures, in order to prevent moisture content changes. Mixture fraction stacked, stacking height should not be commonly more than 2 m, in case the size of particles segregation, uneven distribution. When mixed with ordinary aggregate used, should make the weight aggregate storage respectively, it is forbidden to mix, to guarantee the accuracy of the ingredients.
3.2.2 cement, admixture, additive should be put in storage, waterproof, moisture-proof warehouse in order to prevent the cement scleroma, admixture moisture content change, powdered admixture failure, fluid additive concentration changes.
3.3 raw materials measurement and sampling measurement:
3.3.1 light weight aggregate measurement: appropriate USES volume metering, also USES the weight measurement, but it must be strictly test the moisture content of aggregate, remove outside its moisture content, the weight of the water to guarantee the accuracy of the ingredients. Ordinary sand by weight. When volume metering, must use the special measuring carts or dedicated volume meter, every dish we will strictly measurement.
When using weight measurement, the use of carts, must car weighing, discharge is much less. Has the hopper and the measuring equipment of form a complete set, using automatic or semi-automatic feeding, need to adjust the doumen switch of schedule, to ensure accurate measurement.
Light weight aggregate metering the allowable deviation of plus or minus 3% or less.
3.3.2 rainfall distribution on 10-12 cement measurement: using bagged cement, must according to purchase batch of random sampling measurement. General approach of each lot of cement should be random 10 bags of weight, and calculate the average actual weight of each bag. Is less than the calibration weight to make up the bag is opened, or will be subject to the actual weight of each bag of cement, adjust the thickness of aggregate, the amount of water and other material, according to a given to determine each coil construction mix proportioning. When using bulk cement, should every dish precision weighing measurement. Cement measurement deviation should be allowed + 2% or less.
3.3.3 admixture and mixture of measurement: bags powdered admixture and mixture, should according to each batch in selectiving examination 10 bags of weight, and measuring average weight for each bag, to make up less than the calibration weight. For bulk or large packaging admixture, should according to the construction of each dish dosage is measured in advance in its place, and in the form of a small package to stir site. Set aside. Liquid admixtures to stir increases with the increasing use and balance to check its concentration, measured with a measuring cylinder. Additives and the mixture of measurement deviation should be allowed to plus or minus 2% or less.
3.3.4 mixing water must dish measuring flow meter reading, or use the water tank water level tube mark meter. Its every dish allow deviation plus or minus 2% or less.
3.4 light weight aggregate concrete mixing charge process of:
3.4.1 track lightweight aggregate concrete mixing, bibulous rate is less than 10% appropriate USES secondary feeding process. Will be put into blender with 1/2 weight aggregate water mixing about 1 min, first add the cement mixing a few seconds, and then add the remaining water and admixtures, and continue to stir until 2 min, the method of feeding and mixing process diagram are:
Half the total water consumption
The aggregate 1/2 total water use, water mud additive
Mixing water and aggregate mixture mixing of concrete mixture
Fine aggregate
Lightweight aggregate bibulous rate is greater than 10% of the concrete mixing, appropriate USES prewetting aggregate feeding and mixing process. The general light aggregate prewetting before mixing, according to the order of the coarse aggregate, cement, fine aggregate into blender summary, to be put in a blender mixing barrel 0.5 min dry mixing, and then with water and admixture mixing 2.5 min, the method of feeding and mixing process diagram are:
Water and coarse aggregate net water admixtures
Water compote stirring mixing concrete mixture
Fine aggregate
Rule 3.4.3 adopted since the fall of the mixer feeding and mixing process is: first add 1/2 of the total amount of water, then add the thickness of aggregate and cement mixing lmin, plus surplus water continued to stir 2 min, the method of feeding and mixing process diagram are:
1/2 of the aggregate total water consumption total water use 1/2
Water stirring mixing mud mixture mixed concrete mixture
Fine aggregate
3.4.4 using forced mixer feeding and mixing process is: first cast of coarse aggregate, cement, fine aggregate, mixing lmin, then add water to mixing of not less than 2 min. The method of feeding and mixing process diagram are:
The aggregate total water use admixtures
Water compote stir stir the mixture mixing of concrete mixture
Fine aggregate
3.5 the first set mixing concrete problems that should be paid attention to:
3.5 l before mixing concrete, adding water idle for several minutes, after being churn fully wetting, will more than water is clean.
3.5.2 first plate of mixing concrete, cement mortar to stick wall mixture ratio. Take pre mixing method, namely the use of lightweight aggregate concrete mixture ratio design of a given first put into blender mixing raw materials, the time must be more than double, to be part of the mortar paste on the mixer are compared.in addition, then the rest of the discharged mixture (secondary feed mixing reoccupy), then the normal mixing can be performed.
3.6 mixing time control and inspection: made of lightweight aggregate concrete mixing the shortest time, than ordinary concrete mixing time should be extended to 60 ~ 90 s, general for the 180 s; When mixed with admixture, stirring time should be extended appropriately.
Discharge: 3.7 should be a little out of material, visual appearance quality of mixture, such as visual inspection qualified before discharging. Each coil must be out of the mixture.
3.8 light weight aggregate concrete mixing quality inspection:
3.8.1 check of lightweight aggregate concrete mixing raw materials used in varieties, specifications and usage, each working class at least twice a day. The rain period construction, to increase the water content of lightweight aggregate inspection and measurement.
3.8.2 check in pouring location of lightweight aggregate concrete slump and workability, each class more than two times. Stage rain, winter construction and a change in grade of lightweight aggregate concrete, to enhance the number of detection.
3.8.3 within each class, when light weight aggregate concrete mixture ratio due to outside influences have change, should check in time.
3.8.4 lightweight aggregate concrete mixing time should check at any time.
3.8.5 check appearance quality should be a mixture of lightweight aggregate concrete, stir well, consistent color, good liquidity, adhesiveness and water retention, no bleeding, no segregation. Do not conform to the requirements, should check the reason, adjust in time.
3.8.6 according to the following provisions lien block:
3.8.6.1 100 per mixing disc and no more than 100 m3 with mixing proportion of concrete, the sample shall not be less than once a year.
3.8.6.2 each class of concrete mixing with the mixture ratio of less than 100 plate, the sample shall not be less than once a year.
3.8.6.3 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.
3.8.6.4 each sampling should be at least a set of standard specimen, lien with number groups of condition maintenance of specimen to be retained, according to the requirement of technical disclosure.
In order to ensure the representative block, lien should be before the end of the third set to after mixing concrete mixing sampling between 30 min.
Winter construction of lightweight aggregate concrete mixing: 3.9 during that time, demand for raw materials, mixing time, raw material, heating, mixture out of the pot temperature requirements, etc., should be seriously implemented "standard of ordinary concrete mixing process on site" in article 3.9 and the concrete structure engineering construction and acceptance standard ".
3.9.1 weight aggregate shall not contain ice and snow and frozen clumps.
3.9.2 winter appropriate USES the secondary feeding of lightweight aggregate concrete mixing, secondary mixing process (see rule 3.4 l of the mixing process), in order to improve the workability of lightweight aggregate concrete.
3.9.3 winter should pay attention to test the moisture content of aggregate, timely adjust the water consumption, given slump different components in a timely manner. Than normal temperature slump increases commonly 4 to 6 cm, to ensure that it has good liquidity, adhesiveness and water retention.
4 quality standards
4.1 ensure projects:
4.4.1 lightweight aggregate concrete used in the cement, aggregate, admixture, mixture specifications and varieties and must be in conformity with the relevant provisions of the construction specification and quality.
Inspection method: inspect raw materials factory certificate and test report.
4.2.2 assess the strength of lightweight aggregate concrete block, must according to the concrete strength inspection criteria (GBJ107 87) sample making.
Inspection method: check the strength of lightweight aggregate concrete block test reports and strength assessment information.
4.2 the basic items:
2 should mix of lightweight aggregate concrete, consistent color, good workability.
Inspection methods; Observe check.
4.2.2 of lightweight aggregate concrete mixture slump should accord with the requirement of construction specifications or their mixture ratio notice.
Inspection methods: field testing and checking construction records.
Holdings in construction of winter water, the heating temperature of aggregate and concrete mixture out of the pot temperature should accord with the requirement of construction specifications.
Inspection methods: field testing and checking construction records.
5 quality problems should be paid attention to
5.1 stir the mixture not divide evenly. Color is not consistent: the main reason is the insufficient mixing time.
Particularly to ensure that the winter construction and add the additive, enough time to stir the mixture.
5.2 poor workability, its produce loose mixture is not sticking together and aggregate segregation, floating or mixture to form a mass of unfavorable casting. The main reason is: lightweight aggregate gradation is poor; Sand ratio is too small; Raw materials inaccurate measurement; Or short mixing time. Should overcome the defect carefully, in order to guarantee the good workability of mixture.
5.3 mixture slump is not stable. Master is not accurate, the main reason is that water thickness determination of the change of moisture content in aggregate not promptly, failed to timely adjust the water consumption. Followed by water measurement is not accurate, much less dosage of water. This phenomenon must be overcome to ensure the immanent quality of mixture.
5.4 when using admixture, appropriate in aggregate after absorbing water. To avoid excessive aggregate pore of admixture of absorption. Especially liquid admixtures, use prewetting aggregate, admixture should join with residual water at the same time. Join powder admixture can be made into liquid according to the former method, can also be mixture with cement to join at the same time, to ensure the uniform mixing.
6 quality records
This technology standard should have the following quality records:
6.1 cement factory certification or test certification.
6.2 cement second-round exam list.
6.3 the sand test report.
6.4 light fine aggregate test report.
6.5 light aggregate test report.
6.6 additive product certificate and the certificate of quality.
Dosage of 6.7 admixture in the test report and test report.
6.8 gap of fly ash bricks.
6.9 test report of fly ash.
6.10 concrete of notice.
6.11 concrete construction log (including winter logs).
6.12 concrete early identification.
6.13 concrete block strength test report.
6.14 concrete strength evaluation records.
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