Civil Engineering - Soil Mechanics and Foundation Engineering - Discussion

Presence of organic matter in the soil.

Not pressure of organic matter.

Porosity has nothing to do with the passage of water through the soil much, it is the measure of pores present. In other words, it is the measure of how much water can the soil mass retain. As clay particles are the smallest so their intermolecular voids sum up to me much greater than that of sand. So, the pores present in clay mass is highest so is its water retaining capacity and so is its porosity.

Clay have more surface area than sand, thats why clay have more porosity than sand. As a thin water film is just on particles of clay and have less voids, permeability of clay is less than sand.

Can anyone explain option C?

We know that clay is less permeable then sand. And permeability is directly proportional to porosity then how clay is more porose then sand.

1. The main advantage is that it can withstand high temperatures so that it can be used in refractories, foundries and other workshops where high temperatures are involved.

2. The initial setting time is 3 hours than compared to that of PPC cement. And the final setting time of cement is 5 hours.

3. High Alumina Cement evolves great heat when setting so that these cements can be used in colder temperatures.

4. It is highly resistants to even concentrated acids and thereby it is widely used in chemical industries.

5. It sets fast and it attains a strength of 40 N/mm2 in just one day and 50 N/mm2 in three days.

Porosity and permeability are directly proportional and its fact that porocity of clay is more then that of sand but in case of clay, particle are electrically charged and due to charged partical waters are hold by clay.

Yes, porosity (No of the pore) is more in clay but it's not continuous.

I think porosity is the number of pores. Not the holding capacity.

@Chintu is right. Porosity is water holding capacity. So clay is more porous than sand.