Table of Contents
- 1 How is plasticity of clay measured?
- 2 How much does clay expand when wet?
- 3 How do you quantify plasticity?
- 4 How plasticity is introduced in clay?
- 5 How can you tell if clay is expansive?
- 6 What is dispersive clay?
- 7 Does clay absorb water in a cylinder?
- 8 Does clay change volume when filled with water?
How is plasticity of clay measured?
As with other types of materials, a compression test can be used to evaluate the plasticity of clays. Baran et al. formulated their workability concept for clays using compression tests in cylindrical samples, allowing to determine the optimum amount of moisture for each clay studied.
How much does clay expand when wet?
They absorb water and expand (swell), as much as ten percent or more when wet, and crack (shrink) when dry. In addition, the water content in expansive clay soils can freeze, compounding the swelling problem with frost heave issues.
What happens when clay is compressed?
Clays are compressible. If a moist mass of clay is subjected to compression, moisture and air may be expelled, resulting in volume reduction which is not immediately recovered when the load is removed.
Does clay expand?
As they get wet, the clay minerals absorb water molecules and expand; conversely, as they dry they shrink, leaving large voids in the soil. Soils with smectite clay minerals, such as montmorillonite, exhibit the most profound swelling properties.
How do you quantify plasticity?
Measuring of plasticity is based on the principle of impact deformation using a sample with a defined diameter and height deformed by a free falling plate with a given mass. It is defined as the ratio between the water responsible of tile contraction and the total water; Bigot curves show this information.
How plasticity is introduced in clay?
The plasticity of clays is related to the morphology of the plate-like clay mineral particles that slide over the others when water is added, which acts as a lubricant. As the water content of clay is increased, plasticity increases up to a maximum, depending on the nature of the clay.
Does clay expand when frozen?
Due to the open pore structure of fired clay moisture can be trapped in the form of rain, snow and humidity by capillary action. When the pot freezes this moisture then expands into ice crystals causing the pot to crack or chip.
What is shrinkage in clay?
Shrinkage in the drying process occurs due to the loss of water layers. The finer the particle size of the clay, the more water layers; hence the more shrinkage. Clay shrinkage can impact glaze fit and poor glaze fit can cause crazing or glaze shivering problems and reduced strength of your fired wares.
How can you tell if clay is expansive?
So you’ll want just the opposite – massive, deep cracks in the dry soil. They will tend to be very plastic, high water holding capacity, and relatively low density (due to water content). There is general trend that fine grained expansive soils tend to be high plasticity clays.
What is dispersive clay?
Dispersive clay soils can be a problem for many practices or structures. In appearance, they are like normal clays that are stable and somewhat resistant to erosion, but in reality they can be highly erosive and subject to severe damage or failure. This accounts for these soils’ cohesive, nonerosive behavior.
How do you identify organic materials in clay?
Any material floating on top of the water or particulate matter that settled on top of the clay is organic material Mark a line on the side of the jar with a marker or a piece of tape where you see a separation between the three layers. Measure the distance between the lines you marked with a tape measure and write these numbers down.
How do you calculate the volume of clay in a cylinder?
If, with 100 cc of water, the cylinder was full, than that will be the requisite volume of clay required, provided that you have drained out the water while placing the moulded clay inside the cylinder. If the volume of cylinder > 100 cc, as the diagram suggests, than volume of clay required = volume of cylinder, i.e., > 100 cc as well.
Does clay absorb water in a cylinder?
Now as for the volume required,you have to ensure that volume of clay = volume of space inside cylinder. Yes, it does. Clay absorbs water, so if you’re planning to make the clay fit the cylinder containing water, you have to make it a bit more voluminous than it was originally (where the volume of the clay is same as inside volume of cylinder).
Does clay change volume when filled with water?
Yes, it does. Clay absorbs water, so if you’re planning to make the clay fit the cylinder containing water, you have to make it a bit more voluminous than it was originally (where the volume of the clay is same as inside volume of cylinder). The reason why clay changes volume is due to difference in trapping of air within it.