Name: how cement curing changes porosity
Uploaded: 2024-11-07T14:48:30.000Z
Duration: 1 min 18 s
Channel: JoVE

As fresh cement paste sets, it transitions from a fluid state to a solid mass, entrapping water in various forms, such as gel water, capillary water, and combined water.
Gel water, which is trapped within the pores of the cement gel, typically constitutes approximately 28% of the total volume of the cement gel.
Around 23% of the mass of dry cement consists of the combined water that is associated with the various products resulting from the hydration process.
When the cement paste has more water than is needed for hydration, the excess water forms capillary pores, which constitute about 18.5% of the original cement volume and are often water-filled.
The ratio of the combined volume of gel and capillary pores to the overall volume of the cement paste determines the total porosity of the cement paste.
The water-to-cement ratio is a crucial factor, as excess water creates more capillary pores, leading to higher porosity and potentially weaker hardened cement paste.
Proper curing can reduce porosity by allowing continued hydration, which fills capillary pores with hydration products.

porosity in cement paste

Porosity in Cement Paste

The porosity of concrete is a measure of the void spaces within its structure. These spaces impact its strength and durability significantly. When water and cement interact, a chemical reaction called hydration creates a semi-solid paste. This paste includes combined water, making up approximately 23% of the cement&#39;s dry mass, and gel water, which fills minuscule voids known as gel pores, accounting for about 28% of the cement gel volume.
The balance of water to cement in the mix is critical&#8212;it influences the extent of hydration and, thereby, the porosity and strength of the cured concrete. In an ideal hydration process, extra space not occupied by solid hydration products forms capillary pores, representing around 18.5% of the original cement volume. As the concrete cures, continuous hydration can fill the capillary pores with hydration products, increasing the density of the material.
For complete hydration and optimal strength, the curing process must be managed carefully. It allows for additional hydration, reducing porosity by filling the capillary spaces with more stable hydration products and, as a result, densifying the paste. This meticulous process is crucial for achieving durable, high-quality concrete that is less susceptible to environmental and mechanical degradation.

As fresh cement paste sets, it transitions from a fluid state to a solid mass, entrapping water in various forms, such as gel water, capillary water, and ...

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Civil Engineering

Unit 1

Strength of Concrete

KEY TERMS AND CONCEPTS

how cement curing changes porosity

Cement curing changes porosity in the hardened paste. Porosity means the void spaces inside concrete. These spaces affect both strength and durability. When water and cement react, hydration forms a semi-solid paste that traps water in different ways.

Some of that water becomes combined water. It makes up about 23% of the cement's dry mass. Other water stays as gel water, which fills very small voids called gel pores. Gel pores account for about 28% of the cement gel volume.

The water-to-cement ratio is important in the mix. It controls how much hydration can happen. That, in turn, affects the porosity and strength of the cured concrete. In an ideal hydration process, the space not filled by solid hydration products becomes capillary pores, which are about 18.5% of the original cement volume.

As concrete cures, hydration can continue. More hydration products can fill the capillary pores and make the material denser. Careful curing helps complete this process and reduces porosity. The result is durable, high-quality concrete that is less likely to break down under environmental and mechanical stress.

How Cement Curing Changes Porosity

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Cement curing changes porosity in the hardened paste. Porosity means the void spaces inside concrete. These spaces affect both strength and durability. When water and cement react, hydration forms a semi-solid paste that traps water in different ways. Some of that water becomes combined water. It makes up about 23% of the cement's dry mass. Other water stays as gel water, which fills very small voids called gel pores. Gel pores account for about 28% of the cement gel volume. The...

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key terms and concepts

Learn how hydration, gel water, and capillary pores affect cement paste porosity, strength, and durability as concrete cures.

How Cement Curing Changes Porosity | JoVE K12

JoVE Core Civil Engineering offers a foundational exploration of essential construction materials such as bricks, stones, steel, wood, and concrete, along with fluid mechanics topics like flow over immersed bodies, open channel flow, and dimensional modeling. It also covers key surveying concepts, including leveling, traverse adjustments, curve design, topographic mapping, and geospatial technologies (GPS & GIS). Science-in-action videos showcase laboratory research on materials, fluids, and surveying practices in real-world engineering systems.

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How Cement Curing Changes Porosity

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