CXL-1000 Concrete Strength Rapid Tester Strength Tester Wholesale Price

Concrete strength rapid tester strength tester wholesale price
Purpose and scope of application
． Under the condition that the presumption formula for the strength of concrete of the same material has been established in advance, by measuring the rapid hardening strength of a fresh concrete wet-sieved mortar sample after accelerated coagulation and pressure evaporation, the potential standard curing age (resistance) of the concrete sample can be instantly predicted. Compressive and flexural) strength, used for concrete on-site quality management or mix design and adjustment.
． This method is suitable for fresh cement concrete of uniform quality using my country's five major varieties of cement and some special cements as well as commonly used admixtures.
Instruments, equipment and materials
． Press or universal testing machine
The dial range is ~, and the scale reading does not exceed ~. If a small manual press (such as a lightweight press) is used and the scale accuracy cannot meet the above requirements, a press calibration test should be conducted in advance to ensure that the accuracy meets the requirements before use. The press or universal testing machine used should be calibrated regularly (six months to one year). The allowable deviation of the indication value is % of the standard indication value, and the variation in the indication value should be less than %.
． Concrete wet screening and mortar vibrating screening and molding dual-purpose machine (referred to as dual-purpose machine)
It consists of a body, a sieve, a vibrating table, a discharge funnel and other components, as shown in the figure. and pictures. shown.
The body consists of. The motor drives the cam to produce continuous simple harmonic vibration with a frequency of ~ times and an amplitude of . . The sieve aperture is. Lay the machine body flat and install the sieve (Fig.), which can screen the mortar in the concrete. Remove the sieve, turn the machine body over to make it upright, and install the vibration table, test mold and blanking drain
(Fig. ), can vibrate to form wet-sieved mortar specimens.
． Special pressure steamer
Use a pressure steamer equipped with a pressure gauge, as shown in the figure. shown. The dial size of the pressure gauge is, and the measuring range is ~.
Equipped with pressure steamer. Electric stove heating. When placing the mold of the specimen into an autoclave filled with boiling water for pressure steaming and curing,
Under normal circumstances, after about 10 seconds of sealing with the safety valve, the steam pressure in the pot reaches and stabilizes at a temperature of about ℃.
． The special test mold for wet screening mortar includes a removable triple steel mold and a steel cover plate. After the steel mold is assembled, the inner walls are perpendicular to each other, and the effective size is. ． . The trial mold structure is as shown in the figure. As shown, the dimensional accuracy requirements
are as shown in the table. .
． Platform scale: weighing, sensing
． Balance: weighing, measuring. .
． Mortar mixing pot, mixing spatula, knife, square enamel plate (or iron plate, about the size), stopwatch, etc.
． Special coagulant
or special coagulant, the dosage for each test shall be analytically pure or chemical
Test procedures
. Test preparation
() Wipe the test mold clean, apply butter on the contact surface between the surrounding template and the base, and assemble it tightly to prevent slurry leakage. Brush a thin layer of engine oil evenly on the inner wall of the test mold.
() Add water to the pressure steamer to about the height of the steamer tray, boil the water and check whether the pressure steamer is leaking steam. If steam leaks, corresponding improvement measures must be taken (replace sealing rings, etc.).
． Screen the wet-sieved mortar samples of fresh concrete
() While forming standard curing age concrete (compressive and flexural strength) specimens on site or in the laboratory, take representative fresh concrete specimens. Sample ~ spread evenly in the sieve of the dual-purpose machine. The surfaces of the screen and other equipment should be wiped with a damp cloth in advance.
() Start the dual-purpose machine, hold a small shovel and gently stir the concrete mixture in the sieve until there is no mortar on the surface of the coarse aggregate and almost no mortar falling into the receiving tray. In order to prevent the loss of moisture in the sample, the screening work should be done quickly.
() After the concrete is screened, immediately mix the wet-sieved mortar sample in the receiving pan and weigh the mortar sample with a mixing pot wiped with a damp cloth.
． Add coagulant to the mortar sample, flatten the mortar sample, evenly sprinkle the specified amount of coagulant, press the stopwatch to start timing, and immediately stir the mortar quickly with a mixing shovel wiped with a wet cloth
, push. When stirring, rotate the pot in the counterclockwise direction, and stir and press with the shovel in the clockwise direction. Each time you stir, stir and press ~ times, and repeat it about a total of times.
． Molding test piece
() Add the wet-sieved mortar sample with coagulant added into the test mold at one time through the feeding funnel of the dual-purpose machine.
() Start the dual-purpose machine and vibrate the specimen. The vibration molding time is selected according to the concrete slump reference table.
() Remove the test mold from the dual-purpose machine, use a knife to gently scrape off the mortar that is higher than the test mold, smooth it and cover it with a steel cover that has been brushed with engine oil in advance. ． Pressure steaming and curing of specimens
() From the time when the coagulant is added, the specimens with molds are put into the autoclave with boiling water for steaming and curing. The pressure steaming time starts from the time after the lid is added and the valve is pressed, usually . When using fast-hardening cement, it can be shortened to ~ When using retarding admixtures or fly ash mixed materials, it can be extended to. . The appropriate pressure steaming time should be determined through experiments.
() Record the pressure rise time during the pressure steaming process (from when the lid is placed on the pot to when the steam pressure reaches and steam begins to be released). Each test should be basically the same, about 1 to 2 seconds. If an abnormality is found, the cause should be found and dealt with promptly. The test will be invalid.
() When the pressure steaming curing reaches the specified time (the allowable error is), cut off the power, remove the pressure steamer from the electric furnace, remove the valve to release the steam, and after confirming that there is no steam pressure in the pot, open the lid and take it out for testing. The mold should be removed immediately to conduct the compressive strength test of the specimen.
． Determine the compressive strength of fast-hardening mortar
() Check and align the ball seat of the press. The ball seat should rotate flexibly to prevent local or eccentric pressure on the specimen.
() Remove sand or debris from the end face of the specimen and the pressure plate of the press. Place the specimen upright in the center of the pressure plate and apply load evenly until the specimen is destroyed.
Calculation of test results
． Calculate the compressive strength of fast hardening wet screening mortar according to the following formula
In the formula, the compressive strength of accelerated coagulation and pressure steaming fast hardening wet screening mortar ()
Failure load ()
Note: Pressure steaming curing time for. or. When , the intensity is correspondingly recorded as R. or R. .
The pressure area of the specimen ().
The calculation of the strength value of fast hardening mortar is accurate to. .
The arithmetic mean of the measured values of the three specimens is used as the test result. If the difference between any measured value and the median value exceeds
% of the median value, the median value will be taken as the test result. If the difference between any two measured values and the median value exceeds the above regulations, then the test result of the set will be invalid.
． Estimated concrete strength
() Use the empirical formula for estimating the compressive and flexural strength of concrete that has been established in advance and the estimation accuracy meets the usage requirements
(see formula. to formula.), according to the compressive strength of the fast hardening wet screen mortar Strength test result R, presumption standard
Concrete compressive strength R and flexural strength during the curing period.
The compressive strength of the concrete specimen in the formula during the standard curing age ()
R b The flexural strength of the concrete specimen during the standard curing age ()
The speed of accelerated condensation and pressure steaming Compressive strength of hard wet-sieved mortar specimen ()
, b, , b or , B, , B to be determined coefficient (related to the properties of the raw materials and determined through testing).
Note: The method of conducting preliminary tests to establish the empirical formula for estimating concrete strength shall comply with the provisions of the appendix of this regulation.
() When standardizing the compressive and flexural strength of curing, the measured value of the strength of the fast hardening wet screening mortar should be within the regression line range of the strength empirical formula obtained from the preliminary test and shall not be extrapolated.