1st drying phase: heat from sundays is transferred from the environment to evaporate the moisture on surface.
2nd drying phase: the internal moisture is transferred to the surface and is evaporated.
– External factors affecting brick drying
1. Atmospheric temperature: Increased temperature gives higher energy input during the day time in summer. But, sometimes too high temperature causes shrinkage cracks within a few minutes.
2. Relative humidity: Lower relative humidity means lower vapor pressure in the air -> increasing the drying rates. (humidity is an important factor in the initial drying phase, but it is not heavily dependent on the humidity in the atmosphere in the final drying phase.)
3. Air flow rate: increasing in the air velocity -> enhancing the drying rates.
– Internal factors affecting brick drying
1. Moisture content within the brick : minimum moisture content ranges between 25-35%.
2. Soil characteristics: soil plasticity and the grain size are important characteristics affecting brick drying.
3. Brick moulding type: brick moulding patterns have a role to play in determining the drying rate. The more compact the brick -> the lesser pores and the water content -> dry faster.