Page 240 - Materials Chemistry, Second Edition

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Recycling of Municipal Solid Waste Rejects
• Specific gravity/density of the mixes is less than that of concrete by
25% (compared to the 50% sand mix, the highest density).
• The absorption is less than concrete by more than 95% (compared to
the 50% sand mix, the highest density).
• The 40% sand mix is higher than the lower limit required for strength
of concrete by 17%; the 50% sand mix is lower than the lower limit
by 2.2%; however, temperature increase would only lead to further
deterioration of the property as the 40% sand mix decreased by 18%
at an increase in temperature of 20°C.

While the 50% sand mix is superior in terms of specific gravity and stiffness
modulus, the compressive strength is more important. So the 40% sand mix
is suitable, while increasing the temperature to increase specific gravity. To
overcome the weight issue, usage of perforated armor units should be fur-
ther investigated. It should be noted that the specific gravity of irregular
shapes is 5% less than compacted MSW reject paste.

Beach/canal revetment
Revetment tiles are used to stabilize beaches and river/canal banks. The revet-
ments are sometimes made of rock, concrete bricks, or molded bricks, so con-
clusions on usage were based on comparison of the MSW rejects to the concrete
properties. The strength of the 50% sand mix is compared to data for loading
perpendicular to the plane, and the result is higher than the required strength
of pavement tiles by a minimum of 30%. In addition to the superior perform-
ance a wet/dry test revealed a very slight weight gain of 0.001% overcoming
the specified loss of 0.5%. Thus, the 50% sand mix is suitable for such usage
(Ibrahim, 2006).

6.7 Other Products

Table toppings
After improvements were made to interlocks, manholes, and breakwaters the
idea of table topping emerged. A mold was manufactured with the required
dimensions to produce the topping of the table as shown in Figure 6.11. Poly-
urethane coating is an ideal coating to use to improve the appearance and pro-
tect the environment from any emissions as shown in Figure 6.12.
A grani* top layer, a mixture of rocks and granite granules from indus-
trial wastes of rocks and marble industry, can be used to improve the quality
and appearance of the top layer as shown in Figures 6.12 and 6.13. Rocks are

*Grani is a mixture of granite powder and an organic binder