186 Advanced Process Control and Simulation for Chemical Engineers
Mix no. Cement Aluminum
powder
Sand Water Silica
fume
Melamine Superplasticizer
0.30 0.015
0.35 0.020
5. Determination of
melamine content
(final mix design)
1.0 0.004 1.4 0.35 0.25 1.0 0.012
1.2 0.011
1.4 0.010
1.6 0.009
1.8 0.008
2.0 0.007
2.2 0.006
13.5 DISCUSSION AND RESULTS
13.5.1 Mix Number 1 (Determination of Melamine Content for the First
Trial Mix Design)
Figure 3 present the variations in the compressive strength and dry density for 7 days
age of mortars as a function of the value of melamine substitutes used. It can ini-
tially be seen, to increased melamine, the compressive strength and dry density of
composites decreased. It was found that the highest compressive strength (3.23 MPa)
was obtained for the ratio of cement, aluminum powder, water, sand, and melamine
of 1.0:0.004:0.35:1.0:1.0. However, the compressive strength for this mix proportion
does not exactly satisfy the standard value. Table 5 shows that the specification of non-
load-bearing lightweight concrete according to [1] Type II.
The reduction in the compressive strength due to the addition of melamine aggre-
gates might be due to either a poor bond between the cement paste and the melamine
aggregates or to the low strength that is characteristic of plastic aggregates. Due to this
reason, the proportion of melamine plastic equal to 1.0 was selected for the next mix
design. After the rest of the composition was determined, the melamine plastic was
tested again to nd the suitable proportion.
TABLE 5 Specification of non-load-bearing lightweight concrete [1].
Type Compressive strength (MPa) Density (kg/m3)
Average of three unit Individual unit
II 4.1 3.5 < 1680
TABLE 4 (Continued)

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