One m3 = TON * 2.4
It depends of course a bit on the size of the wheelbarrow and on how high you want to pile up the sand. But a typical wheelbarrow might hold about 85 liters of sand. 1 cubic meter equals 1,000 liters. So you would need about 12 wheelbarrow loads to get 1 cubic meter.
3
With dry sand. 1.602 tonnes
The density of sand can vary, but a common value is around 1,600 kg/m^3. Assuming this density, 1 cubic meter of sand would weigh 1,600 kg. If a bag of sand typically weighs around 20 kg, you would need 80 bags of sand to fill 1 cubic meter.
About One
it is 100 bags of sand/ballast
Sand is not a living thing and does not have cubs!
It will depend on (a) the bulk density of the dry sand and (b) the moisture content of the wet sand.
3 cubic meter
The weight of sand varies depending on its density, but on average, one cubic meter of sand weighs about 1.6 to 1.8 tons. Therefore, 100 cubic meters of sand would weigh approximately 160 to 180 tons.
The answer will depend on how big (or small) the bags of sand are!
It isn't clear what "units" you are talking about.