aci test 1

1 . What must occur before a sample o f concrete can be taken from a revolving
drum mixer?

• All water and admixtures must be added to the mixer

When sampling from a stationary or revolving drum mixer, what is collected
and when is it taken during discharge?

In two or more portions of concrete
At regularly spaced intervals
From the middle of the batch

How are the sample portions obtained from the discharge stream of a stationary or revolving drum mixer?

Repeatedly pass a receptacle through the entire discharge stream
Completely divert the discharge stream into a sample container

Describe the procedure for collecting a sample from a paving mixer.

Discharge the contents o f the paving mixer
Obtain samples from at least five different portions of the pile

What is the minimum size for a sample when strength test specimens are to be molded?

1 f

What i s the maximum allowable time between obtaining the first and final portions of the composite sample?

15 min

What action i s required after the individual concrete samples have been transported to the place where tests are to be performed?

Combine and remix the samples with a shovel

What should be done if the concrete contains aggregate larger than is
appropriate for the size of the molds or equipment being used?

Wet sieving (screening)

Start the tests for slump, temperature, and air content within how many minutes after obtaining the final portion of the composite sample?

5 min

Start molding specimens for strength tests within how many minutes after fabricating the composite sample?

15 min

From what must the concrete sample b e protected?

Sun, wind, and rapid evaporation Contamination