Specific heat is a term that indicates the amount of heat needed to raise the temperature of a substance by one degree Celsius. It is a thermodynamic property of the substance. In SI specifications, we recognize specific heat through symbol 'c' and the unit is Joule per Kelvin.
Specific Heat of Soil
There are two things are vital, when you will go for measuring the specific heat of soil mass.
- Injecting amount of heat to a known mass of soils and
- Measuring the change in temperature in the process
Soil is a poor heat conductor, so it is not an easy experiment to perform.
Specific heat of dry soil is 0.2 Cal/g and water’s specific heat is 5 times higher than that, 1 Cal/g. Moist soils are generally cooler because the heat energy gets spent in evaporation of soil moisture.
If Cs is the specific heat of the soil, we can calculate this from the following equation.
Cs= C1M1+C2M2+C3M3……+ CnMn [cal/g (Â°C)]
Here, M is denoting mass weight in grams.
Standards Calculating Specific Heat of Soil
1 kilogram (kg) of soil mass should increase the temperature by 1o. Surrounding temperature and atmospheric pressure during the experiment are significant. The room temperature should be 25o C and pressure should be sea level pressure which is 760 mm in Mercury.
Factors Determining Specific Heat
- Temperature and Pressure
Specific heat is a thermodynamic property that fluctuates due to the temperature and pressure deflections. Inappropriate temperature fails to receive the heat and the uneven pressure makes the process faulty.
- Energetic Degrees of freedom
Larger degrees of freedom create a larger amount of specific heat and vice versa.
Importance of Specific Heat of Soil in Civil Engineering
The Earth which takes all the loads coming from the various forms of superstructures is made of soil. Along with the other properties of soil, the thermal property also contains with equal importance.
Specific Heat is the amount of heat that simply indicates the required heat to change the temperature by unity. This change affects different phenomena including the water content, bulk density of the soil. If the soil is a fine-grained soil, the Atterberg Limits (plastic limit, liquid limit, shrinkage limit, etc) are widely influenced.
All these things change pivotal properties like permeability, compressibility, shear strength, bearing strength, particle sizes and consistency of soil mass.