In this post, you’re going to learn the procedure of the concrete slump test.
To measure the consistency of fresh concrete, we often perform this test on our construction projects.
You’ll learn easy steps to perform this test yourself.
And, in every step, I’ll give you all the technical details that you require in a particular step.
So let’s learn the…
Step-By-Step Procedure Of Concrete Slump Test
You can carry out the test by yourself.
But, it’ll be a lot easier and smoother if you have a helper to assist you.
Step 1: Place Slump Cone Properly
In this step, you’ll learn how to place the slump cone properly on the ground.
Before that, let’s learn about the slump cone.
It is a cylindrical cone.
The bottom diameter of it is 8 inches.
And, the top diameter is 4 inches.
And, It comes with a separate base plate.
As you are now familiar with the slump cone, let’s place the cone.
First, Clean The Mold.
Clean the whole mold -the inner surface and the outer surface.
On the inner surface, use oil. So that concrete doesn’t stick with the mold.
But, make sure no excess oil is on the surface.
Next, Place The Baseplate.
As its name says, a baseplate is a small plate on which the slump cone stands.
Place the base plate on even and firm ground. So that you can perform the test without shaking the slump mold.
Finally, place the slump cone on the baseplate.
Step 2: Collect Concrete Sample
In this step, you’ll collect freshly mixed concrete to perform the slump test.
Actually, the slump test is performed for determining the consistency of concrete where the nominal minimal size of the aggregate doesn’t exceed 38 mm.
So, make sure the aggregate you’re using doesn’t exceed this limit.
Collect enough fresh concrete. So that you don’t run short of concrete to fill the cone while performing the test.
After collecting concrete, begin the test within 5 minutes.
Step 3: Fill One-Third Of The Cone And Compact.
In this step, you’ll fill the one-third portion of the cone with the collected concrete sample.
And, compact them.
First, secure the cone to the baseplate using the cone tabs.
Or, you can use foot-holds to secure the cone.
No matter how you secure it, the cone must remain steady throughout the test.
Next, fill one-third portion of the cone with concrete.
You can use a scoop or a trowel for this.
In my opinion, the scoop is better to handle concrete.
Finally, compact the concrete.
For this, use a tamping rod.
A temping rod is a two feet long 16mm diameter smooth-surfaced steel bar with rounded tips.
Stroke 25 times evenly around the entire cross-section of the concrete with this rod.
Compacting Technique: Align the rod with the slope of the cone. And, stroke starting with the perimeter and continuing in a circular pattern working your way to the center.
Caution: While stroking, don’t hit the base plate with the tamping rod.
Step-4: Fill Two-Thirds Of The Cone And Compact
In this step, you just need to repeat step 3.
For that, fill the two-thirds portion of the cone with the sample concrete.
Pro Tip: While compacting, make sure the tamping rod penetrates the previous layer about one inch.
Step 5: Fill In The Last Third Of The Cone
This time, fill the cone to slightly overflowing.
And, compact the final layer with 25 strokes with the rod penetrating the second layer, but not through.
Pro Tip: While compacting, you’ll see that the concrete sinks below the lip of the mold. If that happens, stop stroking, refill with concrete, and then start stroking again where you left off in the 25 strokes count.
Step 6: Measure The Slump
This is the final step of the concrete slump test.
In this step, you’ll get the measurement of the concrete slump.
First, strike off the excess concrete from the top of the cone.
Use the tamping rod as a screed in a sawing or rolling motion.
Next, clean the extra concrete.
After striking off, you’ll see concrete around the cone.
Caution: Don’t disturb the cone during this cleaning process.
After that, unlock or step off the cone tabs. And, slowly lift the cone vertically.
This shouldn’t take more than 10 seconds.
Pro Tip: Don’t jerk or rotate the cone or lift up at an angle. Because It’ll give false slump reading.
Finally, take the slump measurement.
To do that, invert the cone and place it next to the sample concrete, but not touching it.
Now, place the tamping on the top of the cone.
And, measure the distance between the displaced center of the slummed concrete and the tamping rod.
And, this distance is the slump of the concrete.
It’s typically expressed in millimeters or inches.
Pro tip: If you are unsure of how to find the displaced center, place a coin onto the center of the concrete before lifting the slump cone.
I hope this guide helped you to learn the procedure of the concrete slump test.
Now I’d Like To Turn It Over To You:
Do you need a helper to perform this test?
Or, can you do it yourself?
Either way, let me know by leaving a comment below…