You can't-lb per cubic foot is a measurement of pressure, tonnes is measure of weight. You could convert Ib per cubic foot to tonnes per cubic foot or more usually, gram per cubic centimetre but not lb per cubic foot to tonnes
80 lbs per cubic foot
Typical window glass weighs 156 pounds per cubic foot. For comparison, a cubic foot of aluminum weighs about 168 pounds, and a cubic foot of oak is around 50 pounds.
The weight of concrete totally depends on the weight of the rock aggregate that is in it. In my area, the rock is hard basalt, which is a little heavier than some other rock. The weight per cubic foot is around 156 pounds.
Granite is figured at 168 pounds per cubic foot. If you know the thickness, you can determine the weight per square foot.
About 100 pounds per cubic foot
The average weight of slate is approximately 175 pounds per cubic foot. However, this can vary depending on the specific type and density of the slate.
Granite is figured at 168 pounds per cubic foot. If you know the thickness, you can determine the weight per square foot.
1 cubic yard = 27 cubic feet so 100.00 per cubic yard equates to 100/27 = 3.7 per cubic foot. 3.00 per 5 cubic ft equates to 0.6 per cubic foot - which is definitely less than 3.7 per cubic ft.
Specific weight is the weight of the material per unit volume. Water has the specific weight of 62.43 pounds per cubic foot or 9.807 Newtons per cubic meter.
64 lbs
The weight varies depending on the size of the crushed concrete. Large pieces typically have a calculated weight range of 120 to 130 lbs per cubic foot (i.e. rip rap, rubble) while smaller pieces have a calculated weight range of 135 to 145 lbs per cubic foot (i.e roadbase, soil stabilizer). The reason for the difference is that a cubic foot of large aggregate is not as dense and small aggregate because large aggregate does not compact as tightly as the small rock, creating voids between the aggregate.