Name: concrete durability and water penetration
Uploaded: 2024-11-07T14:48:45.000Z
Duration: 1 min 25 s
Channel: JoVE

투과성은 액체나 가스가 콘크리트를 얼마나 쉽게 통과할 수 있는지를 나타냅니다. 이 특성은 액체를 유지하고 화학적 분해에 저항하는 구조의 불투수성을 보장하는 것과 관련이 있습니다.
콘크리트 투과성은 콘크리트 샘플의 상단을 제외한 모든 면이 밀봉되는 기본 실험실 테스트로 평가됩니다. 그런 다음 가압 된 물을 상단 표면에 적용합니다.
약 10일이 소요될 수 있는 안정 상태에 도달하면 특정 기간 동안 설정된 두께의 콘크리트를 통해 침투한 물의 양이 기록됩니다.
표준 정상 중량 골재로 구성된 콘크리트의 경우 투과성은 시멘트 페이스트의 다공성에 의해 결정됩니다.
수화 시멘트 페이스트의 투과성은 겔 내의 작은 기공 크기에 의해 결정될 뿐만 아니라 더 큰 모세관 기공의 존재에 의해 영향을 받습니다.
수화가 진행됨에 따라 시멘트 페이스트의 투과성이 감소하는데, 이는 원래 물로 채워졌던 공간 중 일부가 폐쇄되기 때문입니다.
일반적으로 0.6 미만의 낮은 물 대 시멘트 비율에서는 모세혈관이 분절되거나 파손되어 유체 흐름을 방해하기 때문에 투과성이 감소합니다.

콘크리트의 투과성

Permeability of Concrete

콘크리트의 맥락에서 투과성은 액체나 기체가 재료를 얼마나 쉽게 통과할 수 있는지를 나타냅니다. 이러한 품질은 콘크리트 구조물의 수밀성과 내구성 및 화학적 공격에 대한 저항성을 평가하는 데 중요합니다. 콘크리트 투과성은 비교 실험실 테스트를 통해 결정할 수 있습니다. 이러한 테스트로는 일반적으로 콘크리트 시편을 측면에서 밀봉하고, 압력을 가하여 상단 표면에 수압을 가하고, 안정 상태에 도달할 때까지 종종 약 10일 동안 통과하는 물의 양을 측정하는 것이 포함됩니다.


 콘크리트의 투과성은 물-시멘트 비율과 수화도에 영향을 받을 뿐만 아니라 시멘트 페이스트의 다공성에도 영향을 받는데, 다공성은 기공 크기 분포에 따라 달라집니다. 모세관 다공성은 분할된 모세관이 상호 연결된 모세관에 비해 투과성을 낮추기 때문에 중요한 역할을 합니다. 시멘트 페이스트가 계속 수화됨에 따라 처음에 물이 차지했던 공극이 닫히면서 투과성이 감소합니다. 내구성 있는 콘크리트의 경우 물-시멘트 비율을 낮추는 것이 유리하며, 이는 더 빠르게 투과성을 낮추는 데 도움이 됩니다.


 콘크리트 배합은 밀도가 높아야 하며 투과성을 낮추기 위해 등급이 잘 매겨진 골재를 사용해야 합니다. 또한, 경화 방법 및 골재 크기와 같은 요인은 투과성에 영향을 미칠 수 있으며, 안개 경화와 같은 특정 경화 조건을 적용하여 원하는 낮은 투과성에 도달하지 않는 한 증기 경화 콘크리트가 일반적으로 습식 경화 콘크리트보다 투과성이 높습니다.

투과성은 액체나 가스가 콘크리트를 얼마나 쉽게 통과할 수 있는지를 나타냅니다. 이 특성은 불침투성을 보장하는 것과 관련이 있습니다.

Education

교육

JoVE Core

Civil Engineering

토목공학

Unit 1

제1단원

콘크리트의 투수성

KEY TERMS AND CONCEPTS

주요 용어 및 개념

concrete durability and water penetration

Concrete durability depends partly on how easily water and gases can move through it. This property, called permeability, is important for judging water-tightness and resistance to chemical attack in concrete structures.

Permeability is measured with comparative lab tests. In a typical test, the sides of a concrete specimen are sealed, water pressure is applied to the top surface, and the amount of water that passes through is measured. The test is often run for about ten days until a steady state is reached.

Several features of the concrete mix affect permeability. The water/cement ratio and the degree of hydration both matter. The porosity of the cement paste also plays a major role. Pore size distribution is important, and capillary porosity can change how easily water moves through the material.

Interconnected capillaries allow more flow than segmented capillaries, which reduce permeability. As cement paste hydrates, its permeability drops because voids that once held water are gradually closed. For more durable concrete, a lower water/cement ratio helps the mix reach low permeability sooner. A dense mix with well-graded aggregate also helps reduce permeability. Curing and aggregate size matter too. Steam-cured concrete usually has higher permeability than moist-cured concrete, although fog curing can be used in some cases to reach low permeability levels.

Concrete Durability and Water Penetration

concrete-durability-and-water-penetration

permeability of concrete

Concrete durability depends partly on how easily water and gases can move through it. This property, called permeability, is important for judging water-tightness and resistance to chemical attack in concrete structures. Permeability is measured with comparative lab tests. In a typical test, the sides of a concrete specimen are sealed, water pressure is applied to the top surface, and the amount of water that passes through is measured. The test is often run for about ten days until a steady...

sulfate attack on concrete

Concrete Damage from Sulfate Exposure

Concrete damage from sulfate exposure starts with a whitish discoloration, often first seen at the edges and corners. As the attack continues, the concrete can crack and spall. This deterioration happens when sulfates react with hardened concrete and create new compounds that take up more space than the materials they replace. Sulfates may enter concrete from soil, groundwater, or industrial effluents. Inside the concrete, they can form calcium sulfate and calcium sulfoaluminate. The reaction...

effect of sea water on concrete

Seawater Damage and Concrete Durability

Seawater can damage concrete by changing its chemistry, increasing porosity, and lowering strength. In marine settings, concrete is exposed to dissolved salts and repeated wetting, so its durability depends on how much water can enter the material. One major form of damage is the breakdown of ettringite and gypsum, two concrete minerals that can dissolve in seawater. As these materials are lost, the concrete becomes more porous. Salt can also crystallize inside pores, especially above the...

acid attack on concrete

Concrete Damage from Low pH Water

Concrete damage from low pH water happens when acids react with the hydrated cement paste. This reaction dissolves the paste, so the concrete becomes softer and weaker. The problem is often seen in chimneys, sewers, and industrial settings. The amount of damage depends on how acidic the water is. When pH falls below 6.5, the attack becomes more severe. A pH below 4.5 can cause major concrete damage. The rate of damage also depends on how fast hydrogen ions move through the cement gel. This...

alkali aggregate reaction in concrete

How Moisture Cracks Alkali-Reactive Concrete

Alkali-aggregate reaction in concrete can weaken a structure when siliceous minerals in the aggregate react with alkaline hydroxides from cement. The reaction makes an alkali-silica gel, which pulls in water and swells. As the gel expands inside the rigid cement paste, it creates pressure that can crack and disrupt the concrete. The damage comes from both osmotic hydraulic pressure and the swelling of the solid reaction products. Particle size also matters. Fine siliceous particles can cause...

corrosion of reinforcement

Why Concrete Can Fail Around Rebar

Steel reinforcement in concrete can corrode when its protective environment changes. Fresh concrete is highly alkaline because of calcium hydroxide, with a pH of about 13. That high pH helps form a passive iron oxide layer on the steel surface, which slows corrosion. Over time, carbonation, chloride ingress, and cracking can weaken this protection. Concrete contains hydrated cement paste with salts, and it acts as an electrolyte. Different areas of the steel then behave as anodic and cathodic...

key terms and concepts

Learn how water moves through concrete, how permeability is tested in the lab, and why mix design and curing affect durability and water-tightness.

Concrete Durability and Water Penetration | 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.

civil engineering

Concrete Durability and Water Penetration

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