Sampling Plastic Concrete

Question 1

This standard practice specifies the _______, _________, and ___________ required to obtain a representative sample of fresh concrete and to assess its traceability to the structure it represents

Answer 1

Procedures, Location, and sample size

Question 2

The procedures used in sampling include every precaution that will assist in obtaining samples that are truly representative of the _________ and ________ of the concrete.

Answer 2

Nature / conditions

Question 3

Intermittent scooping of the sample in shovelfuls or bucketfuls into a wheelbarrow or tray as the concrete continues to flow down the delivery chute is an acceptable technique? T/F

Answer 3

False

Question 4

The concrete sample must be protected at all times from _______, _______, and _______, and from _______

Answer 4

Sun / wind / other sources of rapid evaporation / contamination

Question 5

The minimum size sample for making three 100 mm x 200 mm cylinders is _______,

Answer 5

20 litres

Question 6

When sampling from a truck agitator or truck mixer, the sample shall be taken between the _______, and _______, points of the discharge

Answer 6

10% / 90%

Question 7

When the concrete contains aggregate larger than that appropriate for the size of the moulds or equipment to be used, the sample shall be _______, prior to testing.

Answer 7

Wet Sieved (Except for Density Tests)

Question 8

When sampling for uniformity of mixed concrete, _______, grab samples shall be obtained from _______, portions of the batch

Answer 8

Three / widely separated

Question 9

The temperature of the concrete must be determined within _______, minutes immediately after obtaining the sample

Answer 9

5 minutes

Question 10

Air content, bracket pressure method and bracket measurement, and the test for slump shall both be completed within _______, minutes after sampling, including transportation and remixing.

Answer 10

10 minutes

Question 11

Moulding of compression or flexural strength specimens shall be completed within _______, minutes after sampling, including transport and mixing

Answer 11

20 minutes

Question 12

Air content bracket biometric method bracket shall _______, within _______, minutes after sampling, including transport and remixing

Answer 12

Start / 5

Question 13

What document produced by the concrete supplier contains information relating to identification of the concrete sample?

Answer 13

The delivery ticket

Question 14

Describe the operation of obtaining sample for evaluation of concrete quality.

Answer 14

Contain a single grab sample at one point of the discharge in as short time as possible

Question 15

Between what two points of the mixer discharge must the concrete be sampled?

Answer 15

The 10% and 90% points

Question 16

How is the sample obtained from discharge stream of a mixer truck?

Answer 16

• pass receptacle completely through discharge stream
• or completely divert discharge stream into sample container

Question 17

What is the minimum size of sample to be obtained when strength specimens are to be molded?

Answer 17

20 L on 100 x 200 cylinders
30 L 150 x 300 mm cylinders
55 L when three flexural beams are made

Question 18

From what conditions must the concrete sample be protected?

Answer 18

Sun
wind
rapid evaporation
contamination

Question 19

What must be done between taking the sample from the mixer and performing the test?

Answer 19

Transport the sample to the place where the test are to performed
Remix with the shovel
When multiple containers are used to obtain a grab sample, the sample shall be remixed into a single composite grab sample

Question 20

What is the time limit for completion of sampling?

Answer 20

10 minutes

Question 21

The test for temperature must be completed and how many minutes after obtaining the sample

Answer 21

Five minutes

Question 22

The test for temperature and air content must be completed with how many minutes after the sample has been transported and remix

Answer 22

10 minutes

Question 23

Morning of strength test specimens must be completed within how many minutes after sample has been transported and remixed

Answer 23

20 minutes