Page 230 - Materials Chemistry, Second Edition

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75 Recycling of Municipal Solid Waste Rejects 209
Sieve 1, T 185 C Sieve 2, T 185 C
Sieve 1, T 240 C Sieve 2, T 240 C
Durometer hardness no., shore D 65
70

60

55

50
20 40 60
Sand content, %
FIGURE 6.8 Variation of shore D hardness no. with sand content, sieve size and
mixing temperature (Abou Khatwa et al., 2005)

and mix 6 (60% sand, sieve 2, and temperature 185°C). The average increase in
hardness values associated with increasing the sand particle size for mixes pre-
pared at 185°C and 240°C were 2.25% and 2.02%, respectively. On the other
hand, increasing the mixing temperature showed a more significant effect in
increasing the hardness values. The average increase for mixes prepared with
sieve 1 was 4.82%, while mixes prepared with sieve 2 revealed an average
increase of 4.6%. The increase in hardness values associated with the increase
in mixing temperature can be related to a better adhesion between the poly-
meric matrix and the sand particles.
Based on the above evaluated mechanical properties, mix 12 prepared at
60% sand content using sieve 2 at a mixing temperature of 240°C was selected
as the optimum mix design regarding the proposed paving and tiling applica-
tions. This mix revealed the highest compressive strength and hardness val-
ues, together with a moderate flexural strength that remains higher than the
requirements for clay and industrial floor bricks. Therefore, this mix will be
the main focus for the further service properties evaluation.

Service properties
Abrasion resistance
The abrasion resistance of the bricks to Egyptian Standard for Cement Tiles,
was determined in accordance with the Egyptian standard test method ES 269-
1974 (1974). The testing apparatus consisted of a rotating disk, a specimen-
mounting plate holder, a hopper, and distributor for feeding fresh abrasive. The
loose abrasive utilized was quartz sand graded to pass a 0.9 mm (No. 25) sieve
and retained on a 0.6 mm (No. 28) sieve.