What is aggregate moisture content?
What is aggregate moisture content?
The total moisture content of an aggregate sample is the sum of the absorbed moisture and the free surface moisture. The moisture content of the aggregate is defined at four states. When the aggregate has no moisture on the surface or the interior pores then the aggregate is in a dry (sometimes called oven-dry) state.
Why is moisture content important in aggregates?
Moisture Content This gives aggregate the ability to absorb water. This will effectively reduce the amount of water available for hydration; or conversely, if the aggregate is very wet, add excess water to a cement mix.
How do you measure moisture content of coarse aggregate?
Do not use the combined weight of the sample container plus the aggregate sample. Then divide the weight of the moisture held by the aggregate by the weight of the sufficiently dried sample. Then multiply this value by 100. The resulting value is the aggregate moisture content as a percent.
What is the purpose of adjusting aggregate content of concrete mix with the moisture content of the it?
By using the moisture content and absorption of the aggregates, you can adjust the batch weights to account for the actual moisture condition. If the moisture content is higher than the aggregate’s absorption value, the aggregates will contribute free water to the mix.
What is the ideal aggregate moisture state?
The SSD state is the best choice as a reference state for the following reasons: It represents the “equilibrium moisture” state of the aggregate in concrete; that is, the aggregate will neither absorb water nor give up water to the paste.
What are the types of moisture?
Generally, an aggregate has four different moisture conditions. They are Oven-dry (OD), Air-dry (AD), Saturated surface dry (SSD) and damp (or wet).
What are the properties of coarse aggregate?
Properties of Coarse Aggregates
- Composition.
- Size and Shape.
- Surface Texture.
- Specific Gravity.
- Bulk Density.
- Voids.
- Porosity and Absorption.
- Bulking of Sand.
How do you calculate moisture state of aggregate?
- Moisture States:
- AC = (WSSD – WOD) / (WOD) x 100%
- Effective Absorption:
- EA = (WSSD – WAD) / WSSD x 100%
- Wabs = (EA) Wagg
- Surface Moisture:
- SM = (Wwet – WSSD) / WSSD x 100%
- Wadd = (SM) Wagg
What is aggregate absorption?
Aggregate absorption is the increase in mass due to water in the pores of the material. Aggregate absorption is a useful quality because: High values can indicate non-durable aggregate. Absorption can indicate the amount of asphalt binder the aggregate will absorb.
What is difference between humidity and moisture?
Moisture represents the presence of a liquid containing trace amounts of water. Humidity, on the other hand, is the concentration of water vapor in a gaseous state, present in the air.
What are the methods of moisture content?
The primary methods used are loss on drying and Karl Fischer titration. There are many methods for determination of moisture content. The primary methods used are loss on drying and Karl Fischer titration. There are many methods for determination of moisture content.
How does water absorption differ between fine and coarse aggregates?
The water absorption of the fine aggregate and the water absorption of the coarse aggregates may differ significantly, particularly when they are not coming from the same source or have not been stored in the same conditions.
Why does an aggregate take water from the mix?
Conversely if the aggregates contain a lower moisture content than the water absorption, then the fine and coarse aggregates will take water from the mix in line with their absorption value.
How is the moisture content of an aggregate calculated?
The moisture content can be calculated directly from measurements of (BSG) using the displacement method. Absorption Capacity: Absorption capacity (AC or absorption) represents the maximum amount of water the aggregate can absorb.
What does the absorption value of an aggregate mean?
The water absorption value for aggregates describes the percentage increase in weight between the dry aggregate and the saturated aggregate. Therefore the absorption value is the amount of water which the aggregates are able to hold.