T0532-2020Test method for slump expansion and expansion time of cement concrete mixtures

1Purpose, scope of application, and reference standards

This method specifies the test method for slump expansion and expansion time of cement concrete mixtures.

This method is applicable to aggregates with a maximum particle size not exceeding315mmThe slump shall not be less thanl60mDetermination of slump expansion and expansion time of cement concrete.

Reference standards:

Concrete slump testerJGT248

Mixing and on-site sampling methods for cement concrete mixtures(T0521)

2Instruments and materials

21Collapse tube:Should comply with the current 'Concrete Slump Tester'JGT248The regulations.

22Slump floor:The side length should not be less than1000mA square flat plate with a maximum deflection not exceeding3mmThe steel plate,And the center position and diameter of the slump cone should be marked on the surface of the flat plate200mmThe300mmThe500mm600mm,700mmThe800mmand900mmConcentric circles,Its shape is shown in the figureT0532-1shown

imageT0532-1Schematic diagram of slump bottom plate(unit of measurement:mm)

2.3pestle:diameter16mmlong contract600mm,Steel round rod with hemispherical ends

24stopwatch:The division value is0.1s

25steel ruler:The maximum range is not less than1000mm,The division value is not greater than1mm

6other:Cloth, shovel, spatula, etc.

3Experimental steps

31Wet the bottom plate and slump pad with a sponge or towel,There should be no visible water on the inner wall and bottom plate of the slump:The base plate is placed on a solid horizontal surface,Place the falling cylinder at the center of the bottom plate,Lower edge and200mmThe scale circles overlap,The slump cone remains fixed in position during loading.

32The concrete mixture should be evenly loaded into the slump cone in three layers,Each layer of concrete mixture is loaded,Apply a tamping rod to evenly insert and compact in a spiral shape from the edge to the center25time,After compaction, the height of each layer of concrete mixture sample is about the height of the cylinder13;When inserting and pounding the bottom layer,The pounding rod should penetrate the entire depth,When inserting and pounding the second and top layers,The tamping rod should be inserted through the surface of this layer to the next layer after the top layer is tamped,Remove the loading funnel,Excess concrete mixture should be scraped off,And smooth it along the mouth of the cylinder.

3.3The self compacting concrete mixture should be filled in one go without layering until it is full,And no vibration or compaction is applied throughout the entire loading process,At the same time, excess concrete mixture should be scraped off,And smooth it along the mouth of the cylinder.

34Remove excess concrete around the chassis collapse cylinder,Immediately lift the slump cone upwards at a constant speed along the vertical direction300mmLeft and right heights,It is advisable to control the time when mentioning it37s,Wait for the concrete to stop flowing or extend for a duration of50stime,

A steel ruler should be used to measure the maximum diameter of the unfolded circle of the mixture and the diameter perpendicular to the maximum diameter,The entire process from loading to lifting off the slump cone should be carried out continuously,and40sCompleted internally

35The expansion degree of concrete should be the average of the two diameters perpendicular to each other after the slump expansion of the concrete mixture is terminated,When the difference between two diameter values is greater than50mmtime,Need to remeasure,Accurate measurement tolmm,Result rounding up to5mma

3.6Determine the degree of expansion500mmthe time,namelyTs,The timing should start when the self collapsing cylinder is lifted away from the bottom plate,Using a stopwatch to measure time,Accurate to0.ls

3.7The expansion test should be conducted continuously from the beginning of loading to the measurement of the expansion value of the concrete,And should be in4mmCompleted internally,When coarse aggregate is found to have slurry precipitation in the central pile or at the edges,Explanation should be recorded

4Test Report

The test report should include the following contents

(1)Name and execution standards of the required testing items

(2)Types, specifications, and origins of raw materials, as well as concrete mix proportions

(3)Test date and time

(4)Name, model and number of the instrument and equipment

(5)Environmental temperature and humidity

(6)Record the slump expansion of concrete

(8)Other content to be explained

provisions explanation

This method refers to the "Standard for Testing the Performance of Concrete Mixtures"(GBT50080-2016)And the "Technical Specification for Application of Self compacting Concrete Columns"(JGr2832012)preparation,Filling ability and flowability of cement concrete composites using sub evaluation