Civil Engineering Reference
In-Depth Information
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7.1.2
Mixing Concrete for Small Jobs
The mix design process applies to large jobs. For small jobs, for which a
large design effort is not economical (e.g., jobs requiring less than one cubic
meter of concrete), Tables 7.11 and 7.12 can be used as a guide. The values
in these tables may need to be adjusted to obtain a workable mix, using the
T ABLE 7.11
Relative Components of Concrete for Small Jobs, by Weight*
Air-Entrained Concrete
Non-Air-Entrained Concrete
Maximum
Size of
Coarse
Aggregate
Wet Fine Wet Coarse
Wet Fine Wet Coarse
mm (in.)
Cement Aggregate Aggregate** Water Cement Aggregate Aggregate** Water
9.5 (3/8)
0.210
0.384
0.333
0.073
0.200
0.407
0.317
0.076
1
2
1
2
12.5
0.195
0.333
0.399
0.073
0.185
0.363
0.377
0.075
3
4
1
2
19
0.176
0.296
0.458
0.070
0.170
0.320
0.442
0.068
25 (1)
0.169
0.275
0.493
0.063
0.161
0.302
0.470
0.067
1
1
1
2
37.5
2
0.159
0.262
0.517
0.062
0.153
0.287
0.500
0.060
*Portland Cement Association, 2002.
**If crushed stone is used, decrease coarse aggregate by 50 kg and increase fine aggregate by 50 kg for
each cubic meter of concrete (or decrease coarse aggregate by 3 lb and increase fine aggregate
by 3 lb for each cubic foot of concrete).
T ABLE 7.12
Relative Components of Concrete for Small Jobs, by Volume*
Air-Entrained Concrete
Non-Air-Entrained Concrete
Maximum
Size of
Coarse
Aggregate
Wet Fine Wet Coarse
Wet Fine Wet Coarse
mm (in.)
Cement Aggregate Aggregate
Water Cement Aggregate
Aggregate
Water
9.5 (3/8)
0.190
0.429
0.286
0.095
0.182
0.455
0.272
0.091
1
2
12.5
1
2
0.174
0.391
0.348
0.087
0.167
0.417
0.333
0.083
3
4
19
1
2
0.160
0.360
0.400
0.080
0.153
0.385
0.385
0.077
25 (1)
0.154
0.346
0.423
0.077
0.148
0.370
0.408
0.074
1
1
37.5
1
2
2
0.148
0.333
0.445
0.074
0.143
0.357
0.429
0.071
*Portland Cement Association, 2002.
The combined volume is approximately 2/3 of the sum of the original bulk volumes.
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