DEVELOPING ECONOMICAL ROLLER COMPACTED CONCRETE MIX FOR PAVEMENTS: 3. EXPERIMENTAL WORK & DESIGN(part 2)

Table 7.

S.No. Characteristic Value
1 Specific gravity 2.63
2 Moisture Content 0.1 %
3 Water Absorption 0.5 %
4 Bulk Density :
a. Loose 1549.6 Kg/m3
b. Compacted 1679.4 Kg/m3

Table 8. Sieve Analysis of Sand

Sieve Size 4.75 mm 2.36 mm 1.18 mm 600 ц 300 ц 150 ц 75 ц
% Passing 99.6 98.9 75.3 48.7 10.2 0.8 0.05

Sand conformed to grading zone II as per IS: 383-1970.

3.2.4 Fine Aggregate – Stone Dust:

Locally available stone dust was used in this study. Physical properties of Stone dust used in the experimental work and tabulated as given below.

Table 9. Fineness Modulus / Grading of Fine Aggregate (Stone Dust)

S.No. SieveSize MassRetained in gm Cummulative Mass Retained in gm Cumulative Percentage Retained (%) PercentagePassing(%)
1 4.75 mm 2 2 0.2 99.8
2 2.36 mm 5 7 0.7 99.3
3 1.18 mm 307 314 31.4 68.6
4 600 mic 310 624 62.4 37.6
5 300 mic 210 834 83.4 16.6
6 150 mic 68 902 90.2 9.8
7 Pan 98 1000
Total XC 268.3

Fineness Modulus of Fine Aggregate (Stone dust) = XC/100 = 268.3/100=2.68

Table 10.

S.No. Characteristic Value
1 Specific gravity 2.60
2 Moisture Content 0.1 %
3 Water Absorption 1.2 %
4 Bulk Density:(a)    Loose(b)    Compacted 1374.8 Kg/m3 1715.5 Kg/m3

Table 11. Sieve Analysis of Stone Dust

Sieve Size 4.75 mm 2.36 mm 1.18 mm 600 ц 300 150 ц 75 ц
% Passing 99.8 99.3 68.6 37.6 16.6 9.8 4.8

Fig1Developing Economical Roller_decrypted

Figure 1. Grading Curves of Sand & Stone Dust “GRADING CURVE OF FINE AGGREGATE ”

Test results shows that sand and Stone dust both are as per IS:383, falls in grading zone II and as shown in fig. 4.1, grading curves are more or less same, similarly Results of Specific gravity test of both materials shows nearly equal, hence the think replacement of sand by stone dust is possible.

3.3 Concrete Mix Design, Grade M-20

For experimental work, M-20 grade concrete has been designed using properties of sand, cement and coarse aggregate by IS Code method as given below:

1. Design Stipulation
(a) Characteristic Compressive Strength : 20 N/mm2
(b) Maximum Size of Aggregate : 20 mm
(c) Degree of Workability (Slump) : 0 mm
(d) Degree of Quality Control : Good
(e) Type of Exposure : Moderate
2. Target Mean Strength of Concrete as per IS: 10262

Target mean strength = fck + t x s

= 20 + 1.65 x 4 = 26.6 N/mm2

Hence, the quantities of materials required to be used per cubic meter of concrete has been tabulated as per the mix design:-

Table 12. Actual Quantities Required for Mix

Material Water in kg Cementin kg Fine AggregateIn kg Coarse Aggregatein kg
Per Cu m 186 465 535.808 1142.6038
Ratio 0.40 1 1.1523 2.45
Per Bag of Cement 20 50 57.6135 122.5

Materials Required (For Six Cubes Preparation):- Cement : 10.60 Kg

Sand    : 12.214 Kg

Coarse aggregate: 25.37 Kg

Water    : 4.24 Kg

Six cubes have been casted and 3 cubes each has been tested after 7 days and 28 days of curing. Replacement proportions of coarse aggregate 20 mm with 12 mm metal and sand with quarry dust were varied between 0 to 50% with the following cases:
1.    Constant W/C ratio 0.40
2. Compressive strength for various cubes as per fig. 4.1 and 4.2.

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