Hi Lukahr and others.... On the point of addition rate of epoxy. Using the spreadsheet you can see that a flat addition rate of 10% by weight can be way too dry depending on the density of the sand you use. The density of sand can range from 2600 thru to 3800kg/m3. The addition rate is actually a volume calculation not a weight calculation. So either do the dry stack and water test to determine your required epoxy ratio, or if you know the density of the sand then you can estimate it with the spreadsheet. Looking at this sand blasting media spec you can see the sand density is 3940kg/m3 yet the bulk density is 1970kg/m3 so it comes in the bag at a volume fraction of 1970/3940= 50%. So by tamping this will get better say 60% then you can use the spreadsheet to figure out the epoxy addition if you know the epoxy density. Then you can verify that with the water addition test.... cheers Peter

using rule of mixtures the al2O3 has a e=200GPa plus so 200*.5*.5= 50GPa this is far above any published stiffness for EG that I can find. The best is in the high 30GPa's. So I think the AL2O3 is a great way to go. If you get to 0.6 packing then its 60Gpa which is close to aluminium at 69GPa very good

200GPa modulus of sand
0.5 = sand volume fraction
0.5 = efficiency of round particles in a matrix to transfer strain within the matrix.

normal silica sand is only 69GPa stiffness so the Al2O3 is well ahead of it in this department. In fact it is the same stiffness of steel.