Recycled Thermoset Plastics 185
very close to the results of 28 days. When silica fume was added in the latter mix num-
bers 4 and 5, the test results were presented for 28 days. This is because the presence of
silica fume increases the duration for completion of the chemical reaction. The testing
procedures of dry density, water absorption, and voids were performed according to
[21] and compressive strength was performed according to [21].
TABLE 4 Mix proportions of melamine lightweight composites (by weight).
Mix no. Cement Aluminum
powder
Sand Water Silica
fume
Melamine Superplasticizer
1. Determination of
melamine content
(1st trial mix design)
1.0 0.004 1.0 0.35 1.0
1.5
2.0
2.5
3.0
2. Determination of
sand content
1.0 0.004 1.0 0.35 1.0
1.2
1.4
1.6
1.8
3. Determination
of water content or
water–cement ratio
(w/c)
1.0 0.004 1.4 0.30 1.0
0.35
0.40
0.45
0.50
0.55
4. Determination of
silica fume content
1.0 0.004 1.4 0.35 0.10 1.0 0.005
0.15 0.007
0.20 0.009
0.25 0.012

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