10
SLUMP & CUBE TEST Introduction The slump test is perhaps the most widely used because of the simplicity of the apparatus required and the test procedure. The slump test indicates the behavior of a compacted concrete cone under the action of gravitational forces. The slump test is a practical means of measuring the workability. Changes in the value of slump obtained during a job may indicate changes in materials, in the water content or in the proportions of the mix, so it is useful in controlling the quality of the concrete produced. The test carried out with a mould called the slump cone. The slump cone is placed on a horizontal and non-absorbent surface and filled in three equal layers of fresh concrete, each layer being tamped 25 times with a standard tamping rod. The top layer is struck off level and the mould is lifted vertically without disturbing the concrete cone. The subsidence of concrete in millimeters is termed the slump. After the test, slumps evenly all around is called true slump. In the case of very lean concrete, one half of the cone may slide down the other which called a shear slump or it may collapse in case of very wet concretes. The slump test is essentially a measure of consistency or the wetness of the mix.

Slump Test Report PMM

Embed Size (px)

DESCRIPTION

LOLOW

Citation preview

Page 1: Slump Test Report PMM

SLUMP & CUBE TEST

Introduction

The slump test is perhaps the most widely used because of the simplicity of

the apparatus required and the test procedure. The slump test indicates the behavior

of a compacted concrete cone under the action of gravitational forces. The slump

test is a practical means of measuring the workability. Changes in the value of slump

obtained during a job may indicate changes in materials, in the water content or in

the proportions of the mix, so it is useful in controlling the quality of the concrete

produced.

The test carried out with a mould called the slump cone. The slump cone is

placed on a horizontal and non-absorbent surface and filled in three equal layers of

fresh concrete, each layer being tamped 25 times with a standard tamping rod. The

top layer is struck off level and the mould is lifted vertically without disturbing the

concrete cone. The subsidence of concrete in millimeters is termed the slump. After

the test, slumps evenly all around is called true slump.

In the case of very lean concrete, one half of the cone may slide down the other

which called a shear slump or it may collapse in case of very wet concretes. The

slump test is essentially a measure of consistency or the wetness of the mix.

Objective

To find a workability of the specimen.

To find a consistence of the specimen.

Page 2: Slump Test Report PMM

THEORY: To determine the concrete fulfils the required specification, 2 types of concrete testing to be conducted are slump test and cube test (compression test).

Slump testThis is a site test to determine the workability of the ready mixed concrete just before its placing to final position inside the formwork, and is always conducted by the supervisor on site. However in mid of concreting process , should the site supervisor visually finds that the green concrete becomes dry or the placement of concrete has been interrupted , a re-test on the remaining concrete should be conducted in particular of the pour for congested reinforcement area

Apparatus

1. Tamping rod - straight bar of circular cross section, 16 mm diameter, 600mm

long with both end hemispherical.

2. Inspection Scale - Machine steel, 0-10 cm slump measurement, 1 cm

increment.

3. Base Plate - Steel sheet, carrying handle, 600 x 600 x 5 mm

4. Sampling tray - 1.2 x 1.2 x 50mm deep made from minimum 1.6mm thick non-

corrodible metal.

5. Scoop - Cast alumunium approximately 100mm wide.

6. Trowel - Pointed type

7. Brush - Steel wire

8. Specimen

9. Cone - Made of metal not readily attacked by

cement paste with the following internal

dimensions:

diameter of base 200 ± 2mm

diameter of top: 100 ± 2mm

height 300 ± 2mm

Page 3: Slump Test Report PMM

Cone Tamping rod

Page 4: Slump Test Report PMM

Procedure

1. Filled mold in three equal layers.

2. Each layer is rodded 25 times to settle the concrete, before the next layer is

added.

3. Full mold is ready to be pulled off to measure slump.

4. Remove the cone from the concrete by raising it vertically, slowly and

carefully, in 5 to 10 seconds.

5. Partial mix being revealed by removal of mold.

6. Immediately after the cone is removed, measure the slump to the nearest

5mm by using the rule to determine the height of the cone and of the highest

point of the specimen being tested

SLUMP TEST REPORT Relevant Standards: BS 1881: Part 125: 1983. Testing concrete- Methods for mixing and sampling fresh concrete in the laboratory.

Result

Quantities Cement (kg) Water(kg or litres)

Fine aggregate

(kg)

Coarse aggregate

(kg) – 20 mm size

Per trial mix of 0.0135 m³

2 2.8 4 8

The result of slump test by using the above amount of cement, water, fine aggregate

and coarse aggregate was 10.5 cm collapse slump.

Page 5: Slump Test Report PMM

Cube Test1. 150 mm standard cube mold is to be used for concrete mix and 100 mm standard cube mold

is to be used for grout mix.2. Make sure the apparatus and associated equipment are clean before test and free from

hardened concrete and superfluous water .3. Assemble the cube mold correctly and ensure all nuts are tightened.

4. Apply a light coat of proprietary mold oil on the internal faces of the mold.

5. Place the mold on level firm ground and fill with sampled concrete to a layer of about 50 mm thick.

6. Compact the layer of concrete thoroughly by tamping the whole surface area with the Standard Tamping Bar. (Note that no less than 35 tamps / layer for 150 mm mold and no less than 25 tamps / layer for 100 mm mold).

7. Repeat Steps 5 & 6 until the mold is all filled. (Note that 3 layers to be proceeded for 150 mm mold and 2 layers for 100 mm mold).

8. Remove the surplus concrete after the mold is fully filled and trowel the top surface flush with the mold.

Page 6: Slump Test Report PMM

9. Mark the cube surface with an identification number (say simply 1, 2, 3, etc) with a nail or match stick and record these numbers in respect with the concrete truck and location of pour where the sampled concrete is obtained.

10. Cover the cube surface with a piece of damp cloth or polythene sheeting and keep the cube in a place free from vibration for about 24 hours to allow initial set .

11. Strip off the mold pieces in about 24 hours after the respective pour is cast. Press the concrete surface with the thumb to see any denting to ensure the concrete is sufficiently hardened, or otherwise de-molding has to be delayed for one more day.

Page 7: Slump Test Report PMM

Discussion

We must reduce water content in the concrete for avoid shear failure.

However, the slump test has been found to be useful in ensuring the uniformity

among different batches of supposedly similar concrete under field conditions.

If the slump is not within the desired range, or the mixture is obviously either

too fluid or too stiff, the proportions of the mixture must be change. To make more

fluid and increase the slump, increase the proportion of water and cement without

changing the water/cement ratio. To make the mixture stiffer and decrease the

slump, increase the proportion of aggregates without changing the fine/course

aggregate ratio. Do not just add water to make the mix more fluid; this will weaken

the concrete.

Conclusion

Slump result was 105mm but shear failure which mean collapse. Hence the

concrete is non-acceptable. This happened because there a lot of water content in

the concrete and look wetly during the test. It seems that it is because of one of our

member mistake, which put the water, more than 2.8 liters.

Water content in the concrete, mean higher the workability but lower the

strength. If the cement content higher, the workability also become higher. The good

mix particles, particle shape and size are cubical or rounded, the workability also

become high. We concluded that our specimen is a high workability but shear failure

which mean lateral collapse.