Section 4 Flashcards
the length of the tamping rod used in this test method is
at least 4 inches taller than the height of the measure but no more than 24 inches
what is the required shape of the end of the tamping rod
rounded to a hemispherical tip
what is the required minimum frequency of the vibrator used in this test method
9000 vibrations per min
the outside diameter or side dimension of the vibrating element must be at least ____ but not greater than
.75 and 1.5 inches
what material is the measure made of
typical medal
what is the min thickness of the metal strike off plate
1/4 inch
what is the min thickness for glass or acrylic strike off plate?
1/2 inch
what is the specified weight of the mallet used on measures that are 1/2 cf or smaller
1.25 lbs plus or minus 1/2 lbs
what method of consolidation must be used when the slump is greater than 3 inches
rodding
what method of consolidation must be used when the slump is less that 1 inch
vibration
if rodding method is used for unit weight the measure must be filled in _____ layers
3
for a measure of 1/2 cf what is the required number of strokes of the tamping rod for consolidation of each layer ?
25
when rodding top and middle section how much should the rod penetrate into the level below?
1 inch
If vibration is the method of consolidation, the measure must be filled in _____ approximately equal layers
2
If, after consolidation of the final layer, the concrete level is 1/2 inch above the top of the measure what should be done?
remove enough concrete to ensure you have over filled the measure to approximately 1/8 inch above the top of the measure
after completing the strike off procedure what must be done before weighting the measure and sample?
clean off any excess concrete
calculate the density of the following concrete : volume = .504 cf , mass empty container = 19.6 lbs, mass of measure plus concrete= 92.1
143.8 lbs/cf
Yield calculation: the total mass of all materials batched was 27,300 lbs (12,383 kg). Using the density of the concrete as determined in question 17, calculate yield in cf, in cy, and in m^3
D=143.8
yield = 189.8 cf, 7.031 cy, density of this concrete is 2305 kg/m^3 so yield = 27,300/2305=5.37 m^3
relative yield calculation: the volume designed for the batch Yd was 7 cy. Knowing that the yield was A. 189 cf, 7 cy, and 5.4 m^3 determine the relative yield
1,1,1
Air content calculation - your air meter has been damaged in transit, to the job site. you do however know the theoretical density that was determined in the lab = 151.4 lbs/cf. Using the following density of 143.8 lbs/cf find the air content using density in lbs/cf
(151.4-143.8)/151.4=5%
