Civil Engineering Reference
In-Depth Information
Bulk oven-dry specific
Moisture
Fineness
7.8. Design the concrete mix according to the following conditions.
Design Environment
Pavement slab, Bozeman, Montana (cold climate)
Required design
Slab
Statistical data indicate a standard deviation of compressive
strength of 250 psi is expected (more than 30 samples).
Only air entrainer is allowed.
Available Materials
Air entrainer: Manufacture specification is 0.15 fl oz/1% air/100
lb cement.
Coarse aggregate: 2 in. maximum size, crushed gravel (angular)
Bulk oven-dry specific
Oven-dry rodded
Moisture
Fine aggregate: Natural sand
Bulk oven-dry specific
Moisture
Fineness
7.9 The design of a concrete mix requires of gravel in dry
condition, of sand in dry condition, and of
free water. The gravel available at the job site has a moisture content
of 0.8% and absorption of 1.5%, and the available sand has a mois-
ture content of 1.1% and absorption of 1.3%. What are the masses
of gravel, sand, and water per cubic meter that should be used at the
job site?
7.10 Design a non-air-entrained concrete mix for a small job with a maxi-
mum gravel size of 25 mm (1 in.). Show the results as follows:
a. masses of components to produce 2000 kg (4400 lb) of concrete.
b. volumes of components to produce of concrete.
7.11 Design a non-air-entrained concrete mix for a small job with a maxi-
mum gravel size of Show the results as follows:
a. weights of components to produce 5000 lb of concrete.
b. volumes of components to produce of concrete.
7.12 Why is it necessary to measure the air content of concrete at the job
site rather than at the batch plant? Name one of the methods used to
measure the air content of concrete.
7.13 What do we mean by curing concrete? What would happen if con-
crete is not cured?
7.14 Discuss five different methods of concrete curing.
7.15 Discuss the change in volume of concrete at early ages.
gravity
=
2.659,
Absorption
=
0.5%
content
=
2%
modulus
=
2.47
strength
=
3000 psi
thickness
=
12 in.
gravity
=
2.573,
Absorption
=
0.1%
density
=
120 pcf
content
=
1%
gravity
=
2.54,
Absorption
=
0.2%
content
=
3.67%
modulus
=
2.68
1173 kg/m
3
582 kg/m
3
157 kg/m
3
1 m
3
36 ft
3
1
2
3
4
in.
1 yd
3
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