ACI Verbal Exam

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

• 15 min

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

• 28 L [ 1 cf ]

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

• 5min

What action is 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

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

• 15 min

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

• Discharge the contents of the paving mixer • Obtain samples from at least five different portions of the file

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

From what must the concrete sample be protected?

• Sun, wind, and rapid evaporation • Contamination

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

• Wet seiving

What must occur befor a sample of concrete can be taken from a revolving drum mixer?

•All water and admixtures must be added to the mixer.

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