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Click blue to follow us Coagulation According to the standards of concrete strength inspection and evaluation standard (gbj107), code for acceptance of construction quality of concrete structure engineering (GB 50204), ready mixed concrete (GB / t14902), code for acceptance of quality of underground waterproof Engineering (GB 50208), technical specification for lightweight aggregate concrete (jgj51) and concrete quality control standard （ GB 50164 technical specification for winter construction of Building Engineering (JGJ 104), code for design of mix proportion of ordinary concrete (JGJ 55), code for acceptance of construction quality of building ground engineering (GB 50209), technical specification for testing compressive strength of concrete by rebound method (JGJ / T23) II Inspection item 1
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The slump of concrete mixture shall be tested at the construction site (Weibull consistency shall be tested for dry and hard concrete), and the test block cured under the same conditions and the test block cured for 28 days shall be retained to test its compressive strength
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2
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The impermeability and frost resistance of impermeable concrete and frost resistance concrete poured on site shall be inspected
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3
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The density, slump (Weibull consistency of dry and hard concrete), 3D (or 1D, 7D) and 28d compressive strength of concrete mix proportion shall be measured during trial mixing, and the later strength age shall not be less than 90d
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Note: a the concrete mix proportion used for the first time shall be subject to opening appraisal, and its workability shall meet the requirements of design mix proportion
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At least one group of standard curing specimens should be retained at the beginning of production as the basis for checking the mix proportion
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b
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Before concrete mixing, the moisture content of sand and stone should be measured, and the material consumption should be adjusted according to the test results, and the construction mix proportion should be put forward
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Check every shift
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The frequency of inspection should be increased in rainy and snowy weather
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4
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28d flexural strength and 28d compressive strength of pavement concrete shall be measured
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5
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The 28d compressive strength and dry density of lightweight aggregate concrete should be measured, and the thermal conductivity should be measured if there are thermal insulation requirements
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3、 Sampling requirements (1) representative batch 1 The specimens used to check the concrete strength of structural members should be randomly selected from the place where the concrete is poured
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Sampling and specimen retention shall meet the following requirements: (1) sampling shall not be less than once for every 100 plates of concrete with the same mix proportion and no more than 100m3; (2) when less than 100 plates of concrete with the same mix proportion are mixed in each work shift, the sampling shall not be less than once; (3) when pouring more than 1000m3 continuously at one time, the concrete with the same mix proportion shall not be less than once every 200m3; (4) the concrete of each floor and the same mix proportion shall be sampled at least once; (5) at least one group of standard curing specimens shall be retained for each sampling, and the number of retained groups of specimens cured under the same conditions shall be determined according to the actual needs
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2、 Ready mixed (commercial) concrete ready mixed concrete (commercial concrete), in addition to leaving test blocks in the ready mixed concrete plant according to regulations, the sampling frequency and batch conditions of concrete strength samples shall be carried out according to the following regulations after the (commercial) concrete is transported to the construction site: (1) the concrete samples used for delivery inspection shall be taken at the place of delivery
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The sampling frequency is the same as that of site mixing concrete
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The sampling frequency of slump test sample of concrete mixture shall be consistent with that of concrete strength test
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(2) the samples used for ex factory concrete inspection shall be taken at the mixing place, and the sampling shall not be less than once per 100 plates of concrete with the same mix proportion; When less than 100 plates of concrete with the same mix proportion are used in each work shift, the sampling shall not be less than once; (3) for the quality of ready mixed concrete mixture, each vehicle shall be visually inspected
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For the sample of concrete slump test, the sampling test shall not be less than once for every 100m3 of concrete with the same mix proportion, and it shall not be less than once for less than 100m3 of concrete with the same mix proportion in a work shift
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3、 The impermeability of impermeable concrete and waterproof concrete should be evaluated by the test results of impermeability specimens of curing concrete under standard conditions, and the specimens should be made at the place of pouring
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A group of impermeability test pieces (6 impermeability test blocks) shall be reserved for every 500m3 of continuous pouring concrete in underground works, and each project shall not be less than two groups
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For impermeability specimens of ready mixed concrete, the number of retained groups should be determined according to the scale and requirements of the structure
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For the concrete structure with impermeability requirement in common engineering, the sampling of the same engineering and the same mix proportion concrete shall not be less than once, and the number of retention groups can be determined according to the needs
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4、 Road concrete (1) according to the technical specification for construction of Highway Cement Concrete Pavement (jtgf30), 2 groups of test blocks are prepared for each working shift or every 200m3 mixture, and the average value of 3 test blocks in each group is a statistical data
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(2) for road concrete making compressive strength test block, batch mixing shall be adopted
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When pouring general volume structure (such as foundation, pier, etc.), 2 groups of test blocks shall be made for each unit structure
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(3) when pouring mass structure continuously, 2 groups should be made every 80-200m3 or every working shift
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(4) for the superstructure, one group shall be made for the main members less than 16m long, two groups shall be made for the main members 16-30m long, three groups shall be made for the main members 31-50m long, and no less than five groups shall be made for the main members more than 50m long
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At least 2 groups of small components shall be made for each batch or work shift
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(5) at least 2 groups of bored piles shall be made, 3 groups of piles with a length of more than 20m, and 4 groups of piles with large diameter and long pouring time
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If the shift is changed, the test block shall be made for each shift
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(6) no less than 2 groups of structures (small bridges and culverts, retaining walls) shall be prepared for each work shift
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When the raw materials and mix proportion are the same and mixed by the same mixing station, two groups can be made by combining several or several places
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According to the needs of construction, several groups of test blocks with the same condition of structure maintenance should be made, which can be used as the strength basis for the construction stages of formwork removal, hoisting, prestressed tension and bearing load
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(7) at least one group of test blocks shall be made at arch foot and side wall of shotcrete every 10 meters
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(8) for pavement concrete, the concrete mixture being paved shall be used to make test block, and the curing conditions of test block are the same as that of concrete slab on site
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Two groups of test blocks should be made at the same time for each day or 200m3 of concrete (400m3 for airport), and the age should be 7d or 28d respectively; A group of test blocks shall be added for each 1000-2000m2 concrete to check the later strength, and the age shall not be less than 90d
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5
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The number of cement concrete groups for building floor shall not be less than one group for each floor (or inspection lot)
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When the floor area of each floor (or inspection lot) is more than 1000m2, a group of test blocks shall be added for every 1000m2; If it is less than 1000m2, it shall be calculated as 1000m2
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When the mix proportion is changed, the number of test blocks should be made accordingly（ 2） Sampling quantity 1
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The cube compressive strength and frost resistance test block of ordinary concrete is cube test block, and the size of test block is as follows, 3 in each group
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Allowable minimum size of concrete compressive strength test block table maximum particle diameter of aggregate (mm) test block size (mm) ≤ 31.5100 × one hundred × 100 non standard test block ≤ 40150 × one hundred and fifty × 150 standard test block ≤ 63200 × two hundred × 200 nonstandard test block, 100 nonstandard test block shall be used × one hundred × 100 mm and 200 mm × two hundred × When determining the strength of 200 mm cube, its compressive strength must be multiplied by the coefficient of 0.95 and 1.05 respectively to convert it into the compressive strength value of standard test block.
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