ACI Certification: Performance Checklist
All water and admixtures must be added to the mixer. - ANS-What must occur before a sample
of concrete can be taken from a revolving drum mixer?
In two or more portions of concrete, at regularly spaced intervals, and from the middle of the
batch. - ANS-When sampling from a stationary or revolving drum mixer, what is collected and
when is it taken during discharge?
Repeatedly pass a receptacle through the entire discharge stream. Completely divert the
discharge stream into a sample container. - ANS-How are the sample portions obtained from
the discharge stream of a stationary or revolving drum mixer?
Discharge the contents of the paving mixer. Obtain samples from at least five different portions
of the pile. - ANS-Describe the procedure for collecting a sample from a paving mixer.
28 L (1 cubic foot) - ANS-What is the minimum size for a sample when strength test specimens
are to be molded?
15 minutes - ANS-What is the maximum allowable time between obtaining the first and final
portions of the composite sample?
Combine and remix the samples with a shovel. - ANS-What action is required after the individual
concrete samples have been transported to the place where tests are to be performed?
Wet sieving - ANS-What should be done if the concrete contains aggregate larger than is
appropriate for the size of the molds or the equipment being used?
5 minutes - ANS-Start the tests for slump, temperature, and air content within how many
minutes after obtaining the final portion of the composite sample?
15 minutes - ANS-Start molding specimens for strength tests within how many minutes after
fabricating the final portion of the composite sample?
Sun, wind, and rapid evaporation. Contamination. - ANS-From what must the concrete sample
be protected?
All water and admixtures must be added to the mixer. - ANS-What must occur before a sample
of concrete can be taken from a revolving drum mixer?
In two or more portions of concrete, at regularly spaced intervals, and from the middle of the
batch. - ANS-When sampling from a stationary or revolving drum mixer, what is collected and
when is it taken during discharge?
Repeatedly pass a receptacle through the entire discharge stream. Completely divert the
discharge stream into a sample container. - ANS-How are the sample portions obtained from
the discharge stream of a stationary or revolving drum mixer?
Discharge the contents of the paving mixer. Obtain samples from at least five different portions
of the pile. - ANS-Describe the procedure for collecting a sample from a paving mixer.
28 L (1 cubic foot) - ANS-What is the minimum size for a sample when strength test specimens
are to be molded?
15 minutes - ANS-What is the maximum allowable time between obtaining the first and final
portions of the composite sample?
Combine and remix the samples with a shovel. - ANS-What action is required after the individual
concrete samples have been transported to the place where tests are to be performed?
Wet sieving - ANS-What should be done if the concrete contains aggregate larger than is
appropriate for the size of the molds or the equipment being used?
5 minutes - ANS-Start the tests for slump, temperature, and air content within how many
minutes after obtaining the final portion of the composite sample?
15 minutes - ANS-Start molding specimens for strength tests within how many minutes after
fabricating the final portion of the composite sample?
Sun, wind, and rapid evaporation. Contamination. - ANS-From what must the concrete sample
be protected?
