There is one problem with the use of sand boxes.
Their perceived benefit is not the sand itself .but the voids between the sand.
In other words ..full sound transmission through the sand is hampered by the air between the individual sand pellets.
Now initially this may work to some extent .but sand has a propensity to compact due to gravity, heat, moisture, load and time and many of the voids become smaller and tighter and many disappear altogether thus obviating the initial benefits.
When sand becomes fully compacted its density approaches that of concrete. In fact before the discovery of cement ..compacted sand was used as a base for laying glass mosaics and with the discovery of volcanic ash and pumice by the Minoans, Greeks and then the Romans ..the addition of Pozzolanic lime to fill the voids in the sand mix together with water created the first mortar and then concrete.
Even today ..a compacted mix of 10:1 sand to cement (to fill the voids) can often be used to bed brick, concrete and stone paving.
As there is no really successful method for preventing the slow but inevitable compaction of the sand within a sand box .its efficacy will slowly deteriorate to become virtually zero.
Their perceived benefit is not the sand itself .but the voids between the sand.
In other words ..full sound transmission through the sand is hampered by the air between the individual sand pellets.
Now initially this may work to some extent .but sand has a propensity to compact due to gravity, heat, moisture, load and time and many of the voids become smaller and tighter and many disappear altogether thus obviating the initial benefits.
When sand becomes fully compacted its density approaches that of concrete. In fact before the discovery of cement ..compacted sand was used as a base for laying glass mosaics and with the discovery of volcanic ash and pumice by the Minoans, Greeks and then the Romans ..the addition of Pozzolanic lime to fill the voids in the sand mix together with water created the first mortar and then concrete.
Even today ..a compacted mix of 10:1 sand to cement (to fill the voids) can often be used to bed brick, concrete and stone paving.
As there is no really successful method for preventing the slow but inevitable compaction of the sand within a sand box .its efficacy will slowly deteriorate to become virtually zero.