Name: concrete water resistance and biological protection
Uploaded: 2024-11-07T14:48:38.000Z
Duration: 1 min 22 s
Channel: JoVE

Concrete takes in water due to the surface tension in the capillary pores of the cement paste, which draws in water through capillary action. Waterproofing admixtures are designed to block this absorption.
The effectiveness of waterproofing admixtures depends on the level of water pressure; it can be minimal, like rainfall, intermediate through capillary action, or substantial under hydrostatic pressure in water-holding structures.
Stearic acid and certain vegetable and animal fats are typical examples of such waterproofing admixtures mixed into the concrete and are different from water repellents.
Bacteria, fungi, or insects can harm concrete by causing steel corrosion and staining surfaces. The rough texture of concrete is suitable for bacteria to dwell and propagate, making surface cleaning inadequate.
This admixture might possess antibacterial, fungicidal, or insecticidal properties, like polyhalogenated phenols, dieldrin emulsions, and copper compounds.
The amount of antibacterial admixture added ranges between 0.1 and 10 percent of the cement&#39;s weight, but if the quantity is more than 3 percent, it can compromise the concrete&#39;s strength.

waterproofing and anti-bacterial admixtures in concrete

Waterproofing and Anti-Bacterial Admixtures in Concrete

Concrete&#39;s susceptibility to water absorption is due to the capillary action within the pores of its hydrated cement paste. This action draws water in, creating the need for waterproofing admixtures to prevent such penetration. The efficacy of these admixtures is contingent upon the water pressure, with variations arising from different conditions such as rain, capillary rise, or hydrostatic pressure in structures intended to hold water.
Waterproofing admixtures render concrete hydrophobic, repelling water and altering the interaction between the water and the capillary walls. Common substances used in these admixtures include stearic acid and certain fats derived from plants and animals.
A clear distinction is made between waterproofing admixtures, which integrate with the concrete mix, and water repellents, which are silicone resins applied to the surface. In addition, there are waterproofing membranes, which are bitumen coatings that form an elastic film on concrete.
The presence of bacteria, fungi, or insects can be detrimental to concrete, leading to steel corrosion and surface staining. Given the concrete&#39;s rough texture, traditional cleaning methods are ineffective, requiring an admixture within the concrete that is lethal to these organisms. These admixtures, such as polyhalogenated phenols, dieldrin emulsions, and copper compounds, can be antibacterial, fungicidal, or insecticidal and are mixed into the concrete to protect against biological threats.

Concrete takes in water due to the surface tension in the capillary pores of the cement paste, which draws in water through capillary action. ...

waterproofing-and-anti-bacterial-admixtures-in-concrete

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JoVE Core

Civil Engineering

Unit 1

Admixtures

KEY TERMS AND CONCEPTS

concrete water resistance and biological protection

Concrete can absorb water because of capillary action in the pores of its hydrated cement paste. That movement pulls water into the material. Waterproofing admixtures are added to reduce this penetration and help concrete resist water.

The effect of a waterproofing admixture depends on the water pressure acting on the concrete. Rain, capillary rise, and hydrostatic pressure in structures made to hold water can all affect performance. These admixtures make concrete hydrophobic, which means they repel water and change how water touches the capillary walls.

Common waterproofing ingredients include stearic acid and certain fats from plants and animals. Waterproofing admixtures are mixed into the concrete, while water repellents are silicone resins applied to the surface. Waterproofing membranes are different again. They are bitumen coatings that form an elastic film on concrete.

Concrete can also be damaged by bacteria, fungi, and insects. These organisms can lead to steel corrosion and surface staining. Because concrete has a rough texture, normal cleaning methods do not work well, so an admixture inside the concrete is needed to kill them. Examples include polyhalogenated phenols, dieldrin emulsions, and copper compounds, which may act as antibacterial, fungicidal, or insecticidal additives.

Concrete Water Resistance and Biological Protection

concrete-water-resistance-and-biological-protection

accelerators

Calcium Chloride in Concrete Mixes

Calcium chloride is a concrete admixture that speeds up hardening and helps concrete gain early strength faster. It does not always change the setting time itself, but it can reduce the time needed in practice. This makes it useful in cold weather and in rapid repair work where quick heat generation after mixing is helpful. A common amount is 1 to 2 percent of the cement mass. Its effect can be compared with raising the concrete temperature by 11 degrees Fahrenheit. To spread it evenly through...

retarders

Retarders in Concrete Pouring

Retarders are chemical admixtures used in concrete to slow the setting time. They are especially helpful when one pour must follow another after a delay. By keeping the concrete workable for longer, they can help prevent cold joints and support a more cohesive structure. Retarders can also improve the look of exposed aggregate finishes when they are used in the right amount. Their effect on setting time can be checked with a penetration test. Common retarding substances include sugar,...

plasticizers

Concrete Workability with Plasticizers

Concrete plasticizers are water-reducing chemical admixtures that improve workability and strength. They help concrete use less water while keeping the same flow, reduce cement content without losing workability, or make mixes easier to place in hard-to-reach areas. Plasticizers work by using surface-active agents. These agents create repulsive electrostatic forces between cement particles. The particles disperse more evenly, and the concrete needs about 5 to 15 percent less mixing water. <br...

superplasticizers

Superplasticizers for Stronger Concrete Mixes

Superplasticizers are concrete admixtures that make mixes flow better while using less water. They are strong water reducers, so concrete can be easier to place without losing strength. This makes them useful when concrete must reach tight spaces or heavily reinforced areas without mechanical vibration. These admixtures work through sulfonated melamine or naphthalene formaldehyde condensates. These chemicals give cement particles a negative charge. The particles repel each other and spread out...

additives and fillers in concrete

Concrete Fillers That Improve Performance

Concrete fillers and additives help change how cement paste performs. Pozzolans and blast-furnace slag act as additives or admixtures because they react with calcium hydroxide released during cement hydration. Fine fillers are close in fineness to Portland cement and can improve workability, density, and resistance to capillary bleeding or cracking. Some fillers are hydraulic, which means they can react with water, while others take part in harmless reactions inside the cement paste. A key...

Concrete can absorb water because of capillary action in the pores of its hydrated cement paste. That movement pulls water into the material. Waterproofing admixtures are added to reduce this penetration and help concrete resist water. The effect of a waterproofing admixture depends on the water pressure acting on the concrete. Rain, capillary rise, and hydrostatic pressure in structures made to hold water can all affect performance. These admixtures make concrete hydrophobic, which means they...

key terms and concepts

Learn how waterproofing admixtures help concrete resist water, and how antibacterial, fungicidal, and insecticidal additives protect it from biological damage.

Concrete Water Resistance and Biological Protection | 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.

Concrete Water Resistance and Biological Protection

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