Name: concrete damage from low ph water
Uploaded: 2024-11-07T14:48:46.000Z
Duration: 1 min 21 s
Channel: JoVE

K12 Standards

Alabama Course of Study Science

9-12

Earth and Space Science

Earth's Systems

9-12.ESS.2.4.b

Acid Attack on Concrete

Os ácidos que interagem com o concreto dissolvem a pasta de cimento hidratada, levando a um material amolecido e estruturalmente enfraquecido.
A acidez decompõe o concreto quando o pH da água cai abaixo de 6,5 e a deterioração acelera se o nível de pH cair abaixo de 4,5.
Água com 15 a 60 partes por milhão de dióxido de carbono, como água gelada derretida, pode degradar o concreto. A água turfosa com mais de 60 partes por milhão de dióxido de carbono é altamente corrosiva.
O esgoto doméstico, embora alcalino, corrói os esgotos, principalmente no calor, quando bactérias anaeróbicas transformam compostos de enxofre em sulfeto de hidrogênio, que é oxidado por bactérias anaeróbicas em ácido sulfúrico.
A taxa de difusão de íons de hidrogênio através do gel de cimento também influencia a taxa de ataque, especialmente após o hidróxido de cálcio ter sido dissolvido e lavado.
Os ataques de hidróxido de cálcio podem ser evitados estabilizando-o com silicato de sódio diluído, que forma silicatos de cálcio nos poros do concreto.
A aplicação de tratamentos de superfície como piche de alcatrão de carvão, borracha ou tintas betuminosas e resinas epóxi provou ser eficaz para ataques ácidos gerais.

ataque ácido no concreto

Quando os ácidos entram em contato com o concreto, eles iniciam uma reação química que dissolve a pasta de cimento hidratada. Esse processo leva ao amolecimento e enfraquecimento estrutural do concreto. Esse problema é comumente observado em ambientes como chaminés, esgotos e ambientes industriais. A gravidade do dano aumenta à medida que o pH da água que interage com o concreto cai abaixo de 6,5. Em particular, um pH abaixo de 4,5 pode causar danos significativos ao concreto.

A taxa na qual os íons de hidrogênio se difundem através do gel de cimento também afeta a taxa de ataque ácido, especialmente notável após o hidróxido de cálcio no concreto ter sido dissolvido e lavado. Além disso, a água com níveis de dióxido de carbono entre 15 a 60 partes por milhão, como água gelada derretida, pode degradar o concreto, enquanto a água turfosa com mais de 60 partes por milhão de dióxido de carbono pode ser altamente corrosiva, reduzindo possivelmente o pH para cerca de 4,4.

Até mesmo o esgoto doméstico pode corroer o concreto em esgotos, particularmente sob condições quentes quando bactérias anaeróbicas convertem compostos de enxofre em sulfeto de hidrogênio. Para evitar esses tipos de ataques ácidos, é benéfico estabilizar o hidróxido de cálcio com silicato de sódio diluído, que forma silicatos de cálcio protetores nos poros do concreto. Além disso, tratamentos de superfície como piche de alcatrão de hulha, tintas de borracha ou betuminosas e resinas epóxi têm se mostrado eficazes no combate a ataques ácidos gerais.

Ataque ácido no concreto

Os ácidos que interagem com o concreto dissolvem a pasta de cimento hidratada, levando a um material amolecido e estruturalmente enfraquecido.
A acidez quebra o ...

Education

JoVE Core

Civil Engineering

Engenharia Civil

Unit 1

Unidade 1

Permeability of Concrete

Permeabilidade do Concreto

KEY TERMS AND CONCEPTS

TERMOS E CONCEITOS-CHAVE

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 effect is especially important after calcium hydroxide has dissolved and been washed away.

Carbon dioxide in water can also harm concrete. Water with 15 to 60 parts per million of carbon dioxide, such as melted ice water, can degrade concrete. Peaty water with more than 60 parts per million can be highly corrosive. It may lower the pH to about 4.4.

Sewage can also corrode concrete in sewers. Warm conditions make this worse. In that setting, anaerobic bacteria convert sulfur compounds into hydrogen sulfide. To limit acid attack, calcium hydroxide can be stabilized with diluted sodium silicate, which forms protective calcium silicates in the concrete pores. Surface coatings such as coal-tar pitch, rubber or bituminous paints, and epoxy resins can also help protect concrete.

Concrete Damage from Low pH Water

permeability of concrete

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...

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 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 acids, carbon dioxide, and sewage can weaken concrete, and how sodium silicate and protective coatings help reduce acid attack.

Concrete Damage from Low pH Water | JoVE K12

JoVE Core Civil Engineering provides a foundational exploration of essential construction materials in civil engineering, focusing on bricks, stones, steel, wood, and concrete through easy-to-understand animated videos. This collection covers the properties, manufacturing processes, and practical applications of these materials. Additionally, the accompanied science-in-action videos demonstrate the research experiments performed in laboratories.

civil engineering

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Physical Properties Of Minerals I: Crystals and Cleavage

Source: Laboratory of Alan Lester - University of Colorado Boulder
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Physical Properties Of Minerals II: Polymineralic Analysis

Source: Laboratory of Alan Lester - University of Colorado Boulder
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Types of Building Stone

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4. Obtain, evaluate, and communicate information about the geologic conditions and processes that form different Earth materials.

9-12.ESS.2.4

Igneous Intrusive Rock

Source: Laboratory of Alan Lester - University of Colorado Boulder
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Igneous Volcanic Rock

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Quarrying involves the meticulous extraction of stone from a quarry by either using controlled explosions or precision cutting techniques to remove the ...

a. Plan and carry out investigations to explore the processes that form plutonic (intrusive) and volcanic (extrusive) igneous rocks of differing compositions and textures. Example: Conduct a crystallization experiment to determine how speed of cooling affects crystal size.

9-12.ESS.2.4.a

Acids interacting with concrete dissolve the hydrated cement paste, leading to a softened and structurally weakened material.
Acidity breaks down the ...

Abrasion Resistance of Concrete

Concrete abrasion can occur from vehicular wear on surfaces or abrasive solids in water, which erodes canal linings.
The shot-blast test evaluates ...

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Turbidity and Total Solids in Surface Water

Source: Laboratories of Margaret Workman and Kimberly Frye - Depaul University
Turbidity and total solids are related measurements addressing clarity of ...

b. Analyze and interpret data to explain the effects of mechanical and chemical weathering and erosion on Earth's materials by wind, water, ice, and gravity.

Making a Geologic Cross Section

Source: Laboratory of Alan Lester - University of Colorado Boulder
Geologic maps were first made and utilized in Europe, in the mid-to-late 18th century. ...

c. Construct an explanation using evidence from experiments, models, or data of the processes that create and transform igneous, sedimentary, and metamorphic rocks.

9-12.ESS.2.4.c

Pore Size Distribution

Capillary pores are considerably larger than gel pores, and various pore sizes exist within the hardened cement paste.
In conditions of partial hydration, ...

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Determination of Moisture Content in Soil

Source: Laboratories of Dr. Ian Pepper and Dr. Charles Gerba - The University of Arizona
Demonstrating Author: Bradley Schmitz
Soils normally contain a ...

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Non-destructive Tests for Concrete Strength

Non-destructive tests, such as the rebound hammer test and penetration resistance test, can be used to determine the strength of concrete in an existing ...

d. Plan and conduct an investigation on water's effect on surface and subsurface processes. Examples: Use particles of varying sizes to determine how the speed of water impacts particle distribution. Use the porosity and permeability of particles of various sizes to determine how the size and sorting of particles affects water movement.

9-12.ESS.2.4.d

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Using GIS to Investigate Urban Forestry

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e. Obtain and communicate information about significant geologic characteristics in Alabama and the southeastern United States. Examples: types of rocks, caves, sinkholes, minerals, energy resources

9-12.ESS.2.4.e

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5. Obtain, evaluate, and communicate information about major events in Earth's history.

9-12.ESS.2.5

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Isotopes

Elements have a set number of protons that determines their atomic number (Z). For example, all atoms with eight protons are oxygen; however, the number ...

a. Analyze and interpret data to sequence events in Earth's history, including relative and absolute dating techniques, principles of superposition and crosscutting relationships, igneous intrusions, radiometric dating, and the fossil record.

9-12.ESS.2.5.a

Extinction

The History of Life on Earth
Fossils of organisms that were different from anything alive today had been documented as early as the 17th century, but it ...

b. Construct an explanation based on evidence of how catastrophic and long-term events have impacted life on Earth, including mass extinctions.

9-12.ESS.2.5.b

The Colonization of Land

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Carbon is the basis of all organic matter on Earth, and is recycled through the ecosystem in two primary processes: one in which carbon is exchanged among ...

What is Photosynthesis?

Photosynthesis is a multipart, biochemical process that occurs in plants as well as in some bacteria. It captures carbon dioxide and solar energy to ...

c. Construct explanations from evidence of how the flow of energy through Earth's systems has changed over time. Example: Earth's oxygen level was lowest during the Cryptozoic Eon (Precambrian) and highest in the Carboniferous.

9-12.ESS.2.5.c

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An Overview of bGDGT Biomarker Analysis for Paleoclimatology

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An Overview of Alkenone Biomarker Analysis for Paleothermometry

d. Obtain, evaluate, and communicate information about important tectonic and geologic events that have occurred in Alabama over geologic time. Examples: geologic ages and types of rocks, fluctuations in sea levels, temperature changes

9-12.ESS.2.5.d

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Determining Spatial Orientation of Rock Layers with the Brunton Compass

Source: Laboratory of Alan Lester - University of Colorado Boulder
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Properties of Transition Metals

Transition metals are defined as those elements that have partially filled d orbitals. As shown in Figure 1, the d-block elements in groups 3&#8211;12 are ...

6. Obtain, evaluate, and communicate information about the theory of plate tectonics.

9-12.ESS.2.6

a. Construct an evidence-based explanation of continental drift, basing conclusions on comparisons of coastlines, fossils, ages of rocks, climate, and magnetic patterns.

9-12.ESS.2.6.a

b. Construct an explanation, based on evidence, of tectonic plate movement, types of plate boundaries, and how boundary type relates to specific tectonic features, including mountain ranges, earthquakes, volcanism, volcanic islands, hotspots, mid-ocean ridges, and faults.

9-12.ESS.2.6.b

c. Develop and interpret a model of Earth's internal structure and composition, including inner core, outer core, asthenosphere, lithosphere, mantle, and crust.

9-12.ESS.2.6.c

d. Analyze data to interpret seismic activity and assess the risk of volcanic eruptions and earthquakes in Alabama and other areas in the United States.

9-12.ESS.2.6.d

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7. Obtain, evaluate, and communicate information about the role of energy transfer in wind, precipitation, cloud formation, and front formation.

9-12.ESS.2.7

a. Obtain and communicate information to explain how water cycles through the atmosphere, including condensation, evaporation, clouds, types of precipitation, relative humidity, and dew point.

9-12.ESS.2.7.a

Specific Heat

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Quantifying Heat

Thermal Energy&#160;

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b. Plan and carry out an investigation to determine the differential heating of land and water and explain how these differences create changes in local and global weather. Example: Heat water and soil under lamps for 10 minutes and allow water and soil to cool for 10 minutes, then apply the results to explain land and sea breezes.

9-12.ESS.2.7.b

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Definition and Measurement of Pressure: Atmospheric Pressure, Barometer, and Manometer

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c. Construct an explanation of how air masses, source regions, fronts, weather changes associated with frontal passage (including cold, warm, occluded, and stationary fronts), air pressure, air density, temperature, cloud types, and precipitation are related to each other.

9-12.ESS.2.7.c

Laminar Flow

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The ...

Bernoulli's Equation

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Pressure Gauges

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/files/media/science-education/science-education-thumbs/14712.jpg

d. Use data to construct an explanation of the role of pressure differences in the development of wind systems. Examples: Analyze high and low pressure centers to determine direction of air motion. Calculate pressure gradients to determine the direction of air motion.

9-12.ESS.2.7.d

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Using Topographic Maps to Generate Topographic Profiles

Source: Laboratory of Alan Lester - University of Colorado Boulder
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Variation of Atmospheric Pressure

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e. Analyze and interpret data to create a surface map, including high-pressure and low-pressure systems, isobars, wind barbs, cloud types, precipitation, and fronts.

Concrete Damage from Low pH Water

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