THE IMPORTANCE OF CHEMISTRY TO CIVIL ENGINEERING

Roads
Bridges
Buildings
Dams
Airports
Water supply systems

Civil engineering involves designing and constructing:

Chemistry

_________ is important because it helps engineers understand the materials used in construction.

• Select appropriate construction materials

• Understand how materials react with the environment

• Prevent material deterioration

• Improve durability

• Develop sustainable structures

Chemistry helps civil engineers

• Why concrete hardens

• Why steel rusts

• How water is purified

• Why materials fail under different environmental conditions

Chemistry helps explain:

Safe
Economical
Long-lasting

Understanding chemistry helps engineers design structures that are

Atoms
Molecules
Chemical compounds

Construction materials are made of

Chemical Composition

________ determines the physical and mechanical properties of materials.

Cement

Hydration reactions produce strength.

Concrete

Chemical reactions control setting and hardening.

Steel

Alloy composition determines strength and corrosion resistance

Asphalt

Chemical composition affects pavement durability

Glass

Chemical composition influences transparency and strength.

Polymers

Used as waterproofing materials, coatings, and pipes

Cement

is the primary binding material used in concrete

The major compounds present in Portland cement include:

calcium silicate hydrate (C-S-H) gel and calcium hydroxide

When Cement is mixed with water, these compounds undergo hydration reactions, producing ________________ and ____________

C-S-H gel

________ is responsible for most of the strength of hardened concrete.

• Water-cement ratio

• Curing conditions

• Temperature during mixing and curing

• Quality of aggregates

Concrete performance depends mainly on:

Cement
Water
Fine Aggregates (Sand)
Coarse Aggregates (Gravel or Crushed Stone)
Admixtures (Optional)

Components of Concrete

Cement

Serves as the binding material that holds the aggregates together through the hydration process.

Water

Initiates the hydration reaction and provides workability to the concrete mixture.

Fine Aggregates (Sand)

Fill the spaces between coarse aggregates, improve workability, and reduce voids in the concrete.

Coarse Aggregates (Gravel or Crushed Stone)

Provide strength, stability, and bulk to the concrete

Admixtures (Optional)

Modify specific properties of concrete, such as setting time, workability, strength, and durability.

Corrosion

the gradual deterioration of metals through chemical and electrochemical reactions with the environment.

hydrated iron(III) oxide

Rust forms when iron reacts with oxygen and moisture, producing ___________.

Water or moisture
Oxygen
An electrochemical process
Conditions that break down the protective passive layer

Corrosion generally requires:

Moisture

Promotes electrochemical reactions that cause rust formation

Oxygen

Reacts with iron in the presence of moisture to form rust

Chloride Ions

Break down the protective oxide layer on steel, accelerating corrosion, especially in marine environments

Acidic Environment

Increase the rate of metal dissolution and corrosion

Saltwater Exposure

Provides moisture and chloride ions that significantly accelerate corrosion.

Cracking of concrete

Spalling

Loss of steel cross-sectional area

Reduced bond between steel and concrete

Reduced structural capacity

Shortened service life

Effects of Corrosion

Protective Coatings

Galvanization Adequate Concrete Cover

Low-Permeability Concrete

Corrosion Inhibitors

Cathodic Protection

Prevention

Water Quality

_________ describes the physical and chemical characteristics of water and whether the water is appropriate for its intended use.

pH
Turbidity
Dissolved oxygen
Hardness
Chloride concentration
Heavy Metals

Water Quality

pH

is important because it can affect chemical reactions and other properties of water. It can also influence the effectiveness of certain treatment processes.

Turbidity

refers to the cloudiness or lack of clarity of water caused by suspended particles

Dissolved Oxygen

is the amount of oxygen present in water. DO is particularly important for aquatic ecosystems because aquatic organisms require oxygen.

Hardness

is associated primarily with dissolved minerals.

High hardness, low hardness

____________ can result in scale formation, while ________ can sometimes contribute to corrosion-related problems.

Chloride Concentration

can occur naturally in water but can also come from sources such as salts and human activities.

Heavy Metals

can be present in water due to natural sources or human activities. Because some metals can pose health and environmental concerns, water treatment and monitoring systems may need to detect and remove them when necessary.

Screening
Coagulation
Flocculation
Sedimentation
Filtration
Disinfection
Wastewater Treatment

Treatment Process of Water

Screening

• removes large debris such as sticks, leaves, plastics, and other solid materials from raw water

• It prevents damage to treatment equipment and improves treatment efficiency

Coagulation

• Chemicals are added and rapidly mixed to neutralize the charges of suspended particles, allowing the particles to clump together

• This facilitates the removal of fine suspended solids.

Flocculation

• Gentle mixing promotes the formation of larger particles called flocs

• The flocs can then be more easily settled or filtered

Sedimentation

• allows the heavier flocs and suspended solids to settle at the bottom of the treatment tank.

• It reduces the amount of suspended solids remaining in the water.

Filtration

• Water passes through materials such as sand, gravel, or activated carbon filters to remove remaining particles and impurities.

• produces clearer and cleaner water by removing fine solids and some microorganisms

Disinfection

• uses chlorine, ozone, or ultraviolet (UV) light to destroy harmful microorganisms.

• It helps ensure that water is safe for human consumption before distribution.

Wastewater Treatment

• removes physical, chemical, and biological pollutants from used water before it is discharged into rivers, lakes, or oceans

• Protects public health

• Preserves aquatic ecosystems

• Safeguards drinking water sources

• Reduces environmental pollution

GREEN CONSTRUCTION MATERIALS

Materials used in construction that are environmentally friendly and help conserve natural resources.

FLY ASH CONCRETE

Concrete that uses fly ash, a waste product from coal burning, as part of the mixture

GEOPOLYMER CONCRETE

Alternative concrete that can reduce the use of traditional cement.

RECYCLED AGGREGATES

Crushed concrete and other materials from old structures reused in new concrete.

LOW-CARBON CEMENT

Cement produced in a way that releases less carbon dioxide by reducing clinker content.

RECYCLED STEEL

Steel recovered from old products and reused to make new steel for construction.

RECYCLED ASPHALT PAVEMENT

Old asphalt from roads that is processed and reused in new pavemen

GREEN CHEMISTRY

The use of chemistry to create safer products and processes with less pollution and waste.

LOW-EMISSION CONCRETE

Concrete designed to produce fewer carbon emissions during production.

RECYCLED CONSTRUCTION MATERIALS

Materials from old or demolished structures that are processed and reused

ECO-FRIENDLY COATINGS

Protective coatings that contain fewer harmful chemicals and produce fewer pollutants.

SUSTAINABLE WATER TREATMENT

Methods of treating water that reduce pollution while using fewer chemicals, energy, and resources.

Structural Engineering

Concrete hydration, corrosion prevention, material durability

Geotechnical Engineering

Soil stabilization, soil chemistry, groundwater chemistry

Transportation Engineering

Asphalt chemistry, pavement materials, bitumen modification

Water Resources Engineering

Water treatment, wastewater treatment, water quality analysis

Environmental Engineering

Pollution control, waste management, remediation

Construction Engineering

Cement chemistry, admixtures, curing and quality control