Ceramics, Glass, Masonry and Cementitious Materials

Introduction and context

Construction materials based on minerals and inorganic binders form the durable skeleton and enclosure of most buildings. Bricks, blocks, tiles, stone, glass, mortar, concrete and cementitious composites differ in composition and manufacture, but their performance is governed by related principles: particle packing, porosity, interfacial bonding, moisture movement, thermal response and chemical stability.

For construction technologists, material selection is not simply a matter of strength. A material must be appropriate for its exposure, geometry, construction method, maintenance regime, fire requirements, appearance, cost and environmental objectives. A strong concrete may still fail through inadequate curing; a durable brick may be unsuitable if its absorption is incompatible with the mortar; and a glass façade may satisfy daylight requirements while creating excessive solar heat gain.

Learning objectives

By the end of this chapter, the reader should be able to:

• describe the composition and manufacture of cement, concrete, mortar, bricks, blocks, tiles, stone and glass;
• explain cement hydration and the development of cement paste microstructure;
• distinguish strength, stiffness, permeability, durability and workability;
• select suitable masonry and cementitious materials for common applications;
• explain the functions of admixtures and supplementary cementitious materials (SCMs);
• identify common deterioration mechanisms and construction-control measures; and
• evaluate materials using technical, environmental and professional criteria.

1. Structure–processing–property relationships

A useful materials-science model is:

composition → processing → microstructure → properties → performance

Composition identifies the chemical and mineral constituents. Processing includes crushing, mixing, forming, firing, grinding, casting, curing and finishing. These processes create a microstructure containing solid phases, pores, cracks and interfaces. The microstructure determines measurable properties such as density, absorption, strength and thermal conductivity. Performance is the behaviour of the material in its actual service environment.

Most building ceramics and cementitious materials are heterogeneous. Their properties therefore depend on defects and interfaces as well as on the ideal chemical composition. In general, increasing connected porosity reduces strength and increases permeability, while refining pore size can improve strength and frost resistance if moisture transport is controlled. However, very low porosity is not always desirable: some masonry units require controlled absorption to develop a bond with mortar.

2. Cement and cementitious binders

2.1 Portland cement composition

Portland cement is a finely ground hydraulic binder. “Hydraulic” means that it reacts with water and can harden under water. Its principal clinker minerals are conventionally written as:

• tricalcium silicate, C₃S, approximately 3CaO·SiO₂;
• dicalcium silicate, C₂S, approximately 2CaO·SiO₂;
• tricalcium aluminate, C₃A, approximately 3CaO·Al₂O₃; and
• tetracalcium aluminoferrite, C₄AF, approximately 4CaO·Al₂O₃·Fe₂O₃.

The notation C, S, A and F represents CaO, SiO₂, Al₂O₃ and Fe₂O₃. Cement also contains gypsum or another sulfate source to regulate setting. Minor constituents include alkalis, magnesia and unreacted phases. Actual composition varies with raw materials and manufacturing requirements.

C₃S hydrates relatively rapidly and contributes strongly to early strength. C₂S reacts more slowly and contributes to later strength. C₃A is highly reactive with water; sulfate control is therefore essential. C₄AF contributes less to strength but affects colour and reaction behaviour.

2.2 Manufacture

Manufacture generally follows these stages:

1. limestone and clay or other corrective materials are quarried and proportioned;
2. raw materials are crushed and ground to a fine, chemically uniform raw meal;
3. the meal is heated in a preheater and rotary kiln;
4. calcination decomposes limestone: CaCO₃ → CaO + CO₂;
5. sintering produces clinker nodules at approximately 1,450 °C;
6. clinker is rapidly cooled; and
7. clinker is ground with gypsum and, where permitted, other constituents.

Rapid cooling helps preserve desirable clinker phases. Grinding fineness influences reaction rate: finer cement generally hydrates faster but requires more energy and may increase water demand or shrinkage.

2.3 Hydration and setting

When cement contacts water, dissolution, ion transport and precipitation occur simultaneously. The principal products are calcium–silicate–hydrate (C–S–H), calcium hydroxide (portlandite), calcium aluminate hydrates and sulfate-containing phases such as ettringite. C–S–H is not a single compound with a fixed composition; it is a poorly crystalline, nanoscale binding phase responsible for much of the strength of hardened cement paste.

A simplified representation is:

Here H represents water and CH represents calcium hydroxide. The equation is schematic rather than a balanced chemical equation because C–S–H has variable composition.

Hydration commonly progresses through an initial reaction period, a dormant period, acceleration, deceleration and a long-term diffusion-controlled period. The dormant period permits placing and finishing. Setting is the transition from a fluid or plastic state to a rigid state; hardening is the subsequent development of strength.

The water–cement ratio is:

where m_w is the mass of mixing water and m_c is the mass of cement; both must use the same units. The ratio applies to cement, not necessarily to all cementitious materials. Lower w/c generally produces lower capillary porosity and higher potential strength, provided the mixture can be placed and cured properly. It does not guarantee performance if compaction is poor or curing is inadequate.

Not all mixing water is chemically consumed. Some is physically held in gel pores, while excess water eventually leaves capillary pores. Evaporation from a poorly cured surface can produce plastic or drying shrinkage and cracking.

2.4 Cement paste microstructure

Hardened paste contains C–S–H gel, calcium hydroxide crystals, unhydrated cement, capillary pores and gel pores. The interfacial transition zone (ITZ) between paste and aggregate is often more porous and heterogeneous than the bulk paste. The ITZ is therefore important in concrete cracking, permeability and strength.

Strength is influenced by w/c ratio, degree of hydration, curing temperature, cement fineness, air content, aggregate quality and loading age. Permeability is especially important because water and dissolved salts transport many agents responsible for deterioration.

3. Concrete

Concrete is a composite of cementitious paste, fine aggregate, coarse aggregate, water and, frequently, chemical or mineral admixtures. Aggregate commonly occupies about 60–75% of concrete volume. It reduces cost, controls shrinkage and provides dimensional stability, but aggregate must be clean, strong, properly graded and compatible with the binder.

3.1 Fresh concrete

Important fresh properties include workability, cohesion, bleeding, segregation, setting time and air content. Slump is a field indicator of consistency, not a direct measure of strength. Adding water at site may increase slump but usually increases w/c ratio and can reduce durability. A water-reducing admixture is normally a better method of improving workability while preserving binder proportions.

Concrete must be transported, placed, compacted and finished before significant setting. Vibration removes entrapped air; excessive vibration can cause segregation. Curing maintains moisture and suitable temperature so hydration can continue.

3.2 Hardened concrete

Compressive strength is commonly measured using standard cylinders or cubes. A simplified empirical relationship often used for normal concrete is the water–cement-strength relationship:

where f_c is compressive strength, A and B are empirical constants, and w/c is the water–cement ratio. This is not a universal design equation; constants must be calibrated for the materials, age, curing and test method. Modern mixture design should rely on standards, trial batches and performance data.

Concrete also exhibits tensile weakness, shrinkage, creep and thermal movement. Reinforcement carries tensile stress, but it does not eliminate cracking. Crack control requires appropriate reinforcement, jointing, curing, detailing and restraint management.

Durability mechanisms include carbonation, chloride-induced corrosion, sulfate attack, alkali–silica reaction, freeze–thaw damage, abrasion and fire exposure. Carbonation lowers pore-solution alkalinity and can depassivate steel reinforcement. Chloride ingress can initiate corrosion even when concrete appears sound. Sulfate attack depends on sulfate concentration, binder chemistry, moisture and transport conditions. Alkali–silica reaction requires reactive silica, sufficient alkalis and moisture.

4. Mortar and masonry

Mortar bonds masonry units, seals joints, accommodates dimensional variation and transfers compressive and shear stresses. It generally contains cement or blended cement, fine aggregate, water and sometimes lime or admixtures. Mortar must be compatible with the units and substrate. Excessively strong or stiff mortar can concentrate stresses and damage weaker historic masonry.

Key mortar properties include workability, water retention, bond strength, compressive strength, permeability, shrinkage and durability. A mortar that retains water allows cement hydration and reduces rapid suction into highly absorptive units. Joint tooling and curing influence resistance to water penetration.

Masonry may be load-bearing, non-load-bearing, reinforced or unreinforced. Its behaviour is anisotropic because bed joints and vertical joints interrupt the material. Design must consider unit strength, mortar strength, prism strength, slenderness, eccentricity, lateral loads, moisture and workmanship.

4.1 Bricks and clay products

Bricks are commonly made from clay or shale containing silica, alumina, fluxes and small quantities of organic matter. Manufacturing involves winning and weathering, crushing, mixing, extrusion or moulding, drying and firing. During firing, water is removed, organic matter burns, minerals transform and fluxes promote partial vitrification. The resulting ceramic contains crystalline phases, glassy phases and pores.

Firing temperature and duration affect colour, strength, absorption and dimensional stability. Underfired bricks may be weak and highly absorptive; overfired bricks may be dense, distorted or difficult to bond. Efflorescence results when soluble salts are transported to the surface and crystallize after water evaporates. It is usually an appearance problem, but persistent moisture movement should be investigated.

4.2 Concrete masonry blocks

Concrete blocks use cementitious paste and graded aggregates, often with hollow cores. They are produced by proportioning, mixing, moulding under vibration and pressure, demoulding and curing. Lightweight blocks may use expanded clay, pumice, foamed materials or other low-density aggregates.

Hollow units reduce mass and can accommodate reinforcement, grout and services. Their performance depends on shell and web geometry, density, moisture condition and manufacturing precision. Blocks require protection from excessive early drying and appropriate joint tooling.

4.3 Tiles

Ceramic tiles are formed by pressing or extrusion, dried, and fired once or more. Glazes are glassy coatings fused to the body. Tiles are selected according to water absorption, wear, slip resistance, chemical resistance, thermal shock and dimensional accuracy. Wall tiles may be inappropriate for heavy floor traffic. Tile installation also depends on substrate flatness, adhesive compatibility, joint design and movement accommodation.

5. Natural stone

Natural stone is quarried rock used as masonry, cladding, paving, aggregate or architectural finish. Igneous stones crystallize from molten material; sedimentary stones form from deposited particles or chemical precipitation; metamorphic stones result from heat and pressure.

Important properties include mineral composition, grain size, bedding or foliation, density, absorption, porosity, compressive strength, flexural strength, abrasion resistance, thermal expansion and resistance to weathering. Stone is anisotropic when it contains bedding, foliation or aligned cracks. Samples must therefore be tested in relevant orientations.

Common deterioration includes freeze–thaw damage, salt crystallization, acid dissolution of carbonate stone, staining, biological growth and thermal shock. Stone cladding requires careful anchorage and provision for movement; relying only on adhesive or friction can create serious safety risks. Cleaning methods should be tested because abrasive blasting and strong acids may permanently damage the surface.

6. Glass

Most architectural glass is a silicate glass based primarily on silica, with sodium compounds as fluxes and calcium compounds for chemical stability. Soda–lime–silica glass is the dominant general-purpose type. Borosilicate glass has improved thermal and chemical resistance, while specialized glasses may contain different network modifiers or reinforcing treatments.

Glass manufacture includes batching, melting, refining, forming, annealing and finishing. Float glass is formed as a continuous ribbon on molten tin, producing flat, smooth surfaces. Annealing relieves internal thermal stresses. Tempered glass is heated and rapidly cooled to create surface compression; it has increased bending and impact resistance and breaks into relatively small fragments. Laminated glass consists of glass sheets bonded by a polymer interlayer, retaining fragments after breakage and improving safety and acoustic performance.

Glass properties include transparency, reflectance, solar transmittance, thermal conductivity, thermal expansion, strength and fracture behaviour. Glass is strong in compression but vulnerable to surface flaws and tensile stress. Insulating glass units use sealed cavities, often filled with inert gas, to reduce heat transfer. Low-emissivity coatings reduce radiative heat exchange.

Design must address human impact, thermal stress, wind pressure, edge damage, seal durability, condensation, fire performance and the consequences of breakage. Glazing systems should comply with applicable building and safety regulations rather than relying solely on nominal glass thickness.

7. Admixtures and supplementary cementitious materials

Chemical admixtures are added in small quantities to modify fresh or hardened concrete. Common types include:

SCMs partially replace Portland cement and react physically or chemically. Fly ash, ground granulated blast-furnace slag, silica fume, calcined clay and natural pozzolans are important examples. A pozzolan reacts with calcium hydroxide in the presence of water to form additional binding phases. SCMs can reduce heat of hydration, refine pores, improve later-age strength and reduce embodied carbon, but some mixtures develop strength more slowly and require careful curing.

The binder-to-water ratio should be considered as a water-to-cementitious-material ratio when SCMs are included:

where m_b is the total mass of cement plus SCMs defined as binder for the particular specification. This ratio alone does not predict performance; SCM reactivity, curing, temperature and replacement level are also significant.

8. Selection, testing and quality control

Material selection should begin with exposure and function. A coastal reinforced-concrete element requires resistance to chloride ingress; a cold-region paving unit requires freeze–thaw resistance; a façade stone requires tested anchors and water-management detailing; and a glazed building requires solar-control analysis.

Typical tests include cement fineness and setting time; aggregate grading and absorption; concrete slump, air content and compressive strength; masonry unit absorption and compressive strength; tile water absorption and abrasion; stone absorption and flexural strength; and glass optical, thermal and safety performance. Test results are meaningful only when sampling, conditioning, specimen preparation and laboratory procedures follow recognized standards.

Quality control should include approved sources, batch records, calibration, storage protection, mix verification, curing records, inspection of reinforcement and joints, and nonconformance procedures. Sustainability assessment should consider extraction, transport, manufacturing energy, service life, repairability and end-of-life recovery. Cement reduction is beneficial only when durability and service life are maintained.

9. Illustrative case: selecting a coastal concrete and masonry system

Background

A six-storey apartment building is proposed 300 m from a marine shoreline. The structure includes reinforced-concrete slabs, exposed columns and clay-brick infill.

Problem

The initial specification uses a high-strength concrete with a high cement content and a fluid mixture achieved by adding water on site. Brick units are highly absorptive, and the proposed mortar is substantially stronger than the brick. The risks are chloride-induced corrosion, shrinkage cracking, poor brick–mortar compatibility and premature façade staining.

Analysis

The exposure requires low permeability, adequate cover, reliable curing and crack control. High cement content alone does not ensure durability. Site-added water increases w/b ratio and capillary porosity. Highly absorptive bricks can withdraw water from mortar, reducing hydration at the interface. A very strong mortar may not accommodate movement and may cause cracking through the brick.

Approach and solution

The project team should:

1. specify a performance-based concrete with a controlled w/b ratio and suitable SCM such as slag or fly ash, subject to local standards and verified trial batches;
2. use a compatible water-reducing admixture rather than uncontrolled site water;
3. provide adequate cover, crack-control reinforcement, joints and a documented curing procedure;
4. test chloride resistance or an appropriate permeability-related performance indicator;
5. select brick and mortar combinations based on absorption, strength, movement and bond tests;
6. precondition units as required by the masonry specification and protect fresh masonry from rapid drying and rain; and
7. provide a drained, ventilated cavity and properly detailed flashings and weeps.

Outcome

The revised system reduces transport of chlorides, limits cracking, improves masonry compatibility and manages rainwater. Its success depends on inspection and workmanship as much as on laboratory mixture design.

Learning points

Durability is a system property. Cement chemistry, concrete proportioning, curing, reinforcement detailing, masonry compatibility and façade drainage must be considered together. A material with excellent laboratory strength can perform poorly when construction controls are neglected.

10. Challenges and contemporary developments

The major challenges are reducing greenhouse-gas emissions, maintaining reliable raw-material supply, managing variability in SCMs, recycling composite products and adapting designs to more severe climate exposure. Cement manufacture releases process and fuel-related carbon dioxide, especially during limestone calcination. Current approaches include clinker reduction, calcined clays, slag, natural pozzolans, improved kiln efficiency, alternative fuels, carbon capture and performance-based specifications.

Digital batching systems, sensors and maturity monitoring can improve consistency and identify curing problems. Machine learning may assist mixture optimization, but it cannot replace validated materials data, engineering judgment or regulatory compliance. Automated image analysis can support inspection of cracks and surface defects, although false positives and unseen internal damage remain limitations.

Professional practice must also address responsible sourcing, worker safety, truthful environmental claims, accessibility and public safety. Reuse or recycling claims should be supported by evidence, and substitutions must be reviewed for fire, structural, moisture and durability consequences.

Best-practice checklist

• Match material properties to exposure, function and expected service life.
• Control water content; do not use site-added water as an informal workability adjustment.
• Use trial batches when changing cement, SCM, aggregate or admixture sources.
• Compact and cure concrete and mortar adequately.
• Test masonry compatibility rather than selecting mortar by strength alone.
• Detail drainage, movement joints, flashing and reinforcement continuity.
• Protect glass edges and design for safe breakage and thermal stress.
• Record batch data, test results, curing conditions and nonconformances.
• Evaluate whole-life performance, not only initial purchase price.

Chapter Summary

Cement, concrete, mortar, ceramics, masonry, stone and glass are inorganic construction materials whose performance arises from composition, processing, microstructure and service environment. Portland cement clinker contains silicate, aluminate and ferrite phases that hydrate to form C–S–H and other products. Water–binder ratio, curing, porosity and the interfacial transition zone strongly influence concrete strength and durability.

Concrete is a composite whose aggregate, paste, reinforcement and joints must be designed as a system. Mortar must be compatible with masonry units in strength, absorption, movement and permeability. Bricks and tiles are fired ceramic products whose properties depend on forming and firing. Blocks are moulded cementitious units, while natural stone performance depends on geology, anisotropy and weathering. Glass is a brittle silicate material whose safety depends on surface condition, treatment, framing and breakage consequences.

Chemical admixtures modify workability, setting, air content and cohesion. SCMs can reduce clinker content, refine pore structure and improve durability, but require appropriate curing and verification. Sound professional practice combines materials science with testing, quality control, exposure assessment, safety regulation and whole-life environmental evaluation.

Key Terms

Cement: Hydraulic binder made by grinding clinker with sulfate and possible additional constituents.

Clinker: Kiln-produced nodules containing reactive cement minerals.

Hydration: Chemical reaction between cementitious materials and water.

C–S–H: Calcium–silicate–hydrate binding phase responsible for much cement-paste strength.

Water–cement ratio: Mass of water divided by mass of cement.

Water–binder ratio: Mass of water divided by the specified cementitious binder mass.

Capillary pore: Relatively large pore formed by water not retained in hydration products.

Interfacial transition zone: Region near the aggregate–paste interface in concrete.

Concrete: Composite of binder paste, aggregates, water and optional additions.

Mortar: Cementitious mixture used primarily to bond and joint masonry.

SCM: Supplementary cementitious material that replaces part of Portland cement.

Pozzolan: Siliceous or aluminous material that reacts with calcium hydroxide and water.

Brick: Fired ceramic masonry unit commonly made from clay or shale.

Concrete block: Factory-moulded cementitious masonry unit, often hollow.

Efflorescence: Surface crystallization of soluble salts transported by moisture.

Natural stone: Building material quarried from naturally occurring rock.

Glass: Non-crystalline silicate material formed by melting and controlled cooling.

Tempered glass: Heat-treated glass with surface compression and enhanced safety behaviour.

Durability: Ability to retain required performance under specified exposure conditions.

Workability: Ease with which fresh material can be mixed, placed, compacted and finished.

Review Questions

Short Answer Questions

1. What are the principal clinker minerals in Portland cement?
2. Define hydration and identify the principal strength-giving product of cement hydration.
3. Why does uncontrolled addition of water generally reduce concrete durability?
4. State two important differences between tempered and laminated glass.
5. Why must mortar be compatible with the masonry units it joins?

Long Answer Questions

1. Explain Portland cement manufacture from raw-material preparation to final grinding.
2. Describe cement-paste microstructure and relate porosity to strength and permeability.
3. Compare the manufacture and performance factors of clay bricks and concrete blocks.
4. Discuss major causes of deterioration in reinforced concrete and methods of control.
5. Explain the role, benefits and limitations of chemical admixtures and SCMs.

Analytical / Application Questions

1. A contractor proposes increasing concrete slump by adding water at the placement point. Analyse the likely effects on w/c ratio, strength, permeability, shrinkage and an appropriate alternative.
2. Select a suitable material strategy for a stone-clad coastal building. Identify the relevant stone, concrete, anchor, drainage and inspection requirements.
3. A highly absorptive brick is specified with a very strong, impermeable mortar. Evaluate the likely interface and durability problems and propose a better selection and construction approach.

Multiple Choice Questions with Answers

Question 1

Which cement hydration product contributes most directly to the strength of hardened cement paste?

A. Calcium–silicate–hydrate

B. Gypsum crystals only

C. Unreacted limestone

D. Entrapped air

Correct Answer: A. Calcium–silicate–hydrate

Question 2

The water–cement ratio is calculated as:

A. Mass of cement divided by mass of water

B. Mass of water divided by mass of cement

C. Volume of aggregate divided by mass of cement

D. Mass of SCM divided by volume of concrete

Correct Answer: B. Mass of water divided by mass of cement

Question 3

What is the principal purpose of curing concrete?

A. To remove all chemically bound water

B. To maintain conditions for continued hydration

C. To increase aggregate size

D. To prevent all thermal movement

Correct Answer: B. To maintain conditions for continued hydration

Question 4

Which admixture creates stable microscopic air voids that can improve freeze–thaw resistance?

A. Retarder

B. Accelerator

C. Air-entraining agent

D. Viscosity reducer

Correct Answer: C. Air-entraining agent

Question 5

Which statement best describes a pozzolan?

A. A material that reacts with calcium hydroxide and water to form binding products

B. A coarse aggregate used only for drainage

C. A glass coating applied to tiles

D. A chemical used exclusively to delay setting

Correct Answer: A. A material that reacts with calcium hydroxide and water to form binding products

Question 6

Why is uncontrolled water addition at a concrete placement site generally undesirable?

A. It lowers the water–cement ratio and stops hydration

B. It increases the water–cement ratio and may increase porosity

C. It converts aggregate into cement

D. It guarantees higher durability

Correct Answer: B. It increases the water–cement ratio and may increase porosity

Question 7

Which glass treatment produces surface compressive stresses and relatively small fragments when broken?

A. Annealing only

B. Tempering

C. Laminating with stone

D. Acid washing

Correct Answer: B. Tempering

Question 8

Efflorescence on brickwork is primarily associated with:

A. Crystallization of soluble salts at the surface

B. Melting of the brick during service

C. Loss of all aggregate particles

D. Formation of reinforcement steel

Correct Answer: A. Crystallization of soluble salts at the surface

Question 9

Which factor is especially important when selecting natural stone for cladding?

A. Only its colour under showroom lighting

B. Anchorage, orientation, absorption and weathering behaviour

C. Its ability to hydrate like cement

D. Its water–cement ratio

Correct Answer: B. Anchorage, orientation, absorption and weathering behaviour

Question 10

The interfacial transition zone in concrete is the region:

A. Between the kiln and the raw-material crusher

B. Between aggregate and cement paste

C. Inside a glass interlayer only

D. Between two layers of roof insulation

Correct Answer: B. Between aggregate and cement paste