How do you calculate how much sand and gravel an cement you need to concreat an area 1800 x 1800 x100 deep?

To calculate the amount of sand, gravel, and cement needed for a concrete area measuring 1800 mm x 1800 mm x 100 mm, first convert the dimensions to meters: 1.8 m x 1.8 m x 0.1 m. The volume of concrete required is 1.8 m x 1.8 m x 0.1 m = 0.324 cubic meters. A common concrete mix ratio is 1:2:3 (cement:sand:gravel), which means for every 1 part cement, you'll need 2 parts sand and 3 parts gravel. Based on this mix, you would need approximately 54 kg of cement, 108 kg of sand, and 162 kg of gravel for the given volume.