SLUMP TEST ASTM C143

STANDARD TEST METHOD FOR SLUMP OF HYDRAULIC-CEMENT CONCRETE

ASTM C143/C143M-20


I. SIGNIFICANCE AND USE

This test method is intended to provide the user with a procedure to determine slump of plastic-hydraulic cement concretes.

This test method was originally developed to monitor the consistency of unhardened concrete.

II. APPARATUS

A. Mold 

        

B. Tamping Rod

 

C. Measuring Device

 








        

D. Scoop



III. SAMPLE

The sample of concrete from which test specimens are made shall be representative of the entire batch.

(It shall be obtained in accordance with Practice C172/C172M).

IV. PROCEDURE

1. Dampen the mold and place it on a rigid, flat, level, moist, non-absorbent surface, free of vibration, and large enough to contain all the slumped concrete. Fill the mold in three layers, each approximately one third volume of the mold.

NOTE: One third of the volume of the slump mold fills to a depth of 2 5/8 in. [70 mm]: Two thirds of a volume fills it to a depth of 6 1/8 in. [160 mm].

 

2. Rod each layer 25 times uniformly over the cross section with the rounded end of the rod. For the bottom layer, this will necessitate inclining the rod slightly and making approximately half of the strokes near the perimeter, and then progressing with vertical strokes spirally toward the center. Rod the bottom layer throughout its depth. For each upper layer, allow the rod to penetrate through the layer being rodded and into the layer below approximately 25mm.

3. In filling and rodding the top, heap the concrete above the mold before rodding is started. If the rodding operation results in subsidence of the concrete below the top edge of the mold, add additional concrete to keep an excess of concrete above the top of the mold at all times. After the top layer has been rodded, strike off the surface of concrete by means of screeding and rolling motion of the tamping rod. Continue to hold the mold down firmly and remove concrete from the area surrounding the base of the mold. Raise the mold in 5 ± 2 seconds by a steady lift with no lateral or torsional motion. Complete the entire test from the start of filing through removal of the mold within an elapsed time of 2 ½ minutes.

4. Measure the slump by determining the vertical difference between the top of the mold and the displaced original center of the top surface of the specimen. If a decided falling away or shearing off of concrete from one side or portion of the mass occurs, disregard the test and make a new test on another portion of the sample.

 





V. REPORT

Report the slump in terms of inches [millimeters] to the nearest ¼ in. [5 mm].



 

 

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