Table 5.1 illustrated the physical properties of media beds prepared by mixing laterite soil (LS as fine aggregate) and CSF or AC (as coarse aggregate) with cement (C). The mixing ratio between cement, fine aggregate and coarse aggregate was 1:1:4 (w/w). Our results found that addition of AC into media bed could improve the amount of water sorption and reduce the unit weight of media bed. Water sorption of media bed prepared by LS : CSF had water sorption about 15.7% lower than media bed prepared by LS : AC. Media bed prepared by LS : 50%CSF + 50%AC shown the improvement of water sorption than media bed prepared by LS : CSF. Replacement of coarse LS aggregate (LScoarse) into CSF for media bed prepared by 50%LScoarse + 50%AC shown the improvement of water sorption than media bed prepared by LS : 50%CSF + 50%AC.
Consider the unit weight of media bed, the most lightest was found in media bed prepared by LSfine : AC (0.6 g/cm3) and the most heaviest was media bed prepared by LSfine : 50%LScoarse + 50%AC. Consider the resistance to compressive strength of media bed, negative effect was found in media bed added AC. The compressive strength was reduced with an increase of AC proportion in media bed. Media bed prepared by LSfine : AC had the lowest compressive strength of 8 N/m2. Media beds prepared by 50%CSF + 50%AC and 50%LScoarse + 50%AC had compressive strength in the range between 42 – 66 N/m2. Fig. 52 illustrated the surface geometry of media beds prepared from LS mixed with CSF and AC.