Building Materials: Properties & Characteristics

What are Building Construction Materials?

• Construction materials encompass natural or manufactured substances suited for buildings or their elements.
• Each material possesses unique properties tailored for specific roles, such as concrete for foundations because of stiffness and strength.
• Glass is used for its translucency and thickness.

The Characteristics of Materials

• Building materials are defined by strength, stiffness, elasticity, density, hardness, wear resistance (physical or chemical), fire resistance, thermal conductivity, and appearance.
• Material characteristics are broken into chemical, physical, mechanical, and dimensional categories.

Chemical Characteristics

• Chemical characteristics are molecular related, determining a material's resistance to chemicals like bases, solvents, salts, alkalis, and acids.
• Chemical composition is one such characteristic.
• Acidity or alkalinity is also one such characteristic.
• Weathering is measured against corrosion and impacts building materials' appearance and lifespan.
• Durability, a key chemical trait, allows materials to resist physical abrasion, weather elements (sun, rain, wind), and chemical corrosion.

Physical Characteristics

• Physical characteristics connect to how materials interact with different forms of energy.
• Density is the mass per unit volume of a material, showing its compactness, vital for construction needing material sinking abilities.
• Conductivity includes thermal conductivity, measured in Watts per meter Kelvin (W/m x K).
• Electrical conductivity is measured in Siemens per meter (S/m).
• Acoustic refers to the sound transmission or absorption of material.
• Sound Reduction Index is measured in decibels (db).
• Optical characteristics are classified by their interaction with visible light.
• Combustibility is the ability to ignite or resist ignition.
• Weight refers to the material volume by material density, which is seen as a critical parameter for structural design.

Mechanical Characteristics

• Mechanical characteristics relate to how a material behaves under applied forces, with elasticity and stiffness being most effective for structural needs.
• Strength includes compressive, tensile, and shear strengths, indicating the maximum stress a material can endure without breaking under forces.
• Toughness enables a material to absorb energy and deform significantly without rupturing when impacted or vibrated by stress, also known as impact toughness.
• Stiffness, is measured as k in newtons per meter, it gauges a material's resistance to deformation and the force needed to reach its elastic limit.
• Elasticity is the ability of a material to deform under stress (bend, stretch, compress) and return to its original shape, measured by Young's Modulus.
• There is a certain limit that a material can endure before permanent deformation or breakage occurs.
• Plasticity is when a material undergoes nonreversible shape changes under external forces.
• Ductility is the capacity of a material for large plastic deformations.
• Brittleness describes a material that fractures upon stress with little deformation.
• Hardness measures a material's resistance to being pressed into or scratched by a sharp object.

Dimensional Characteristics

• Dimensional characteristics are determined by size, shape, and finish, and are generally manufactured to standard sizes.
• Color palette considerations for building color must account for context, exterior and interior light, and whether colors render differently under cool or hot light, thus influencing light absorption, reflection, and warmth.
• Material patterns should consider the scale of individual elements, such as bricks or glass, compositions, and inherent patterning like wood grain or stone marbling.
• Texture can be modified during production or on-site finishing to provide a range of surface finishes, from smooth to rough, and matte to polished.

Application of Materials & Components in Construction

• The correct construction material is important when used in specific building components
• Concrete is known for being the most used construction material

Reinforced Concrete

• Reinforced concrete has a wide use for the constuction industry
• Known to encase and bond with steel
• Used for foundations, walls, beams and columns

Concrete

• Made by mixing cement, water and aggregates in suitable proportions.
• It can be formed into any shape with a variety of surface finishes and textures.
• Concrete structures are fire-resistant.
• Concrete consists of the following
  • Cement – made by burning clay and limestone in a rotary kiln.
  • Water – Must be free of clay, salts, and any other organic matter.
  • Aggregates – a combination of sand and gravel
  • Additives and admixtures - an additional composition for the mixture.
  • Water-cement ratio – Ratio of mixing water to cement in a unit volume of concrete mix.

Types of Concrete

• Normal-weight concrete weighs between 2243-2563 kg/m3, depending on the mix design and aggregate used.
• A unit weight of 2400 kg/m3 is typically assumed for design.
• Normal concrete's 28-day compressive strength ranges from 2000 to 4000 psi (13,790–27,580 kPa).
• Structural lightweight concrete uses lightweight aggregates like expanded shale, clay, slate, and slag.
• It has a unit weight less than 1922 kg/m3.
• It has a 28-day compressive strength greater than 2500 lb/sq in. (17,237 kPa).
• Lightweight insulating concrete is used for thermal insulation with aggregates like perlite and vermiculite.
• It weighs from 240–1442 kg/m3 with a 28-day compressive strength from 100 to 1000 lb/sq in. (690–6895 kPa).
• Mass concrete is used in structures like dams where its weight provides strength.
• Very little steel is added for support
• No-slump concrete has a slump of 2.5 cm or less
• Heavyweight concrete is made with heavy aggregates like barite, magnetite, and steel punching, for nuclear radiation shielding.
• Unit weights usually range from 2884-6408 kg/m3.
• Refractory concrete is suitable for high-temperature applications such as boilers and furnaces.
• Precast concrete is cast into the desired shape before placement in a structure.
• Architectural concrete is exposed for view, using special shapes, designs, or finishes for the desired architectural look.

Cement

• Cement is used as the binding material in construction
• A finely ground powder that when mixed with water is set to hard mass

Classification of Cement

• Hydraulic Cement can set and harden underwater
• Non-hydraulic cement cannot set and harden underwater because it requires air to harden

Types of Cement

• Different types of cement are used in construction based on specific requirements
• Strength, setting time, durability, and resistance to environmental conditions
  • Pozzolan cement is a blended hydraulic cement that possesses no cementitious value; with moisture, it reacts chemically with calcium hydroxide at an ordinary temperature.
  • Slag cements are hydraulic cements of granulated blast-furnace slag and lime.
  • Natural cement is limestone calcined under the melting point and ground to powder.
  • Portland cements are clinker pulverized until there are hydraulic calcium silicates
  • Portland Blast-Furnace Slag Cement is an intimate blend of Portland Cement and fine slag.
  • Alumina cement has calcium aluminates.
    • Early high strength, excellent refractoriness, and good resistance against chemical attacks are outstanding properties.
  • Expansive cement contains a constituent for expansion during hydration, setting or hardening, and develops into satisfactory strength.

Types of Portland Cement

• Type I: Normal is a general-purpose cement suitable for all normal applications.
• Type II: Moderate provides better resistance to alkali attack and produces less heat than Type I, suitable where groundwater contains a moderate level of sulfate.
• Type III: High Early Strength provides 190% of Type I strength after 1 day of curing.
• It produces about 150% of the heat of hydration of normal cement during the first 7 days for early removal of forms and in cold-weather concreting.
• Cement Type IV: Low Heat heat produces only 40–60% of the heat produced by Type I cement during the first 7 days with 55% strength by day 7
• Type V: Sulfate Resisting provides maximum resistance to alkali attack; 7-day strength is only 75% of normal cement.
  • It should be placed when concrete will be against soil or water that contains a high sulfate concentration

Properties of Portland Cement

• Fineness
• Soundness
• Time of Setting
• Compressive Strength
• Heat of Hydration
• Loss of Ignition
• Specific Gravity

Aggregates

• Aggregates are comprised of sand and gravel, crushed stone, slag, or other mineral-based material that combines a binding medium to create materials.
• Examples include Portland cement concrete, macadam, mastic, mortar, plaster, or alone as in railroad ballast or filter beds

Classification of Aggregates

• Natural aggregates are sourced via natural deposits with no changes.
  • Sizing, grading, or washing may occur.
• Manufactured aggregates are of mineral origin, resulting from an industrial process.
  • Thermal or other modification happens.
• Fine aggregates pass a 3/8 in (9.5mm) sieve, pass a No. 4 (4.75mm) sieve, and are retained on the No. 200 (75µm) sieve.
• Coarse aggregates are refined on No. 4 (4.57mm) sieve.
• Aggregate is viewed as base-course material when added to structural bituminous concrete slabs.
  • Portland cement concrete and frost preventitive

Water

• Water gives moisture required for cement hydration
• Water ensures water affects the plasticity from the concrete
  • Hydration - a chemical reaction
  • Heat of Hydration - heat produced from water
• Water used for clean mixing will not contain injurious matter
• Potable water is acceptable for mixing

Additives & Admixtures for concrete

• Chemical substances used to improve concretes physical and chemical properties.
• Additive, is to improve properties
• Admixture is the additive when used on conrete

Types of Additives & Admixtures for concrete

• Air-entraining agents enhance freeze-thaw durability by forming millions of non-coalescing air bubbles in the mix.
• Water-reducing agents increase workability without altering consistency.
  • Adding more water impacts strength and durability.
• Retarders slow concrete hardening, offsetting high temperatures and extending setting time, especially in hot zones.
• Accelerators reduce the initial setting time, speeding up hardening and increasing hydration, useful for cold conditions and repair works.
• Pozzolans materials such as fly ash or volcanic ash replace a portion of cement for many risks such as leaching or alkali aggregate reduction

Masonry

• Masonry refers to units formed and hardened into modular units used to make walls and building enclosures.
• Some characteristics are
  • Ability to resist decay, combustion and insects
  • Steel reinforcing increases the strength while decreasing the overall weight

Brick

• Brick is made from clay and can be fired in multiple climates
• Brick can come in different colors and the nominal dimension
• Some types are
  • Face brick
  • Firebrick
  • Glazed brick
  • Pavers

Stone

• Stone is one of the most oldest used building materials.
  • Used for ancient buildings and structures
• A combination of inorganic and mineral substance
• Used in construction can be
  • Igneous
    • Granite
    • Diorite
    • Basalt
    • known for durable, hardness, road construction and weathering
  • Sedimentary
    • Limestone
    • Shale
    • Sandstone
    • Flooring, Walls, Decorative
  • Metamorphic
    • Marble
    • Slate
    • Quartzite
    • Known for Hardness, dense, resistant to weathering.

Qualities to be checked on stone

• Strength
• Hardness
• Workability
• Appearance
• Durability
• Density

Concrete Masonry Units

• Used to build walls and sub surfaces for brick facings
• Comes in hollow or solid blocks and bricks
• Less expensive and stronger than brick
• Lighter in weight
• Types of units depending on the locality and manufacturer
  • Stretcher blocks
  • Bullnose blocks
  • Corner blocks
  • Corner return blocks
  • Double corner blocks
  • Pilaster blocks

Steel

• Commonly used in building products such as windows and doors
• Any of any iron-based alloys having a carbon content that is used for steel framing
• Elasticity
• Measure in terms of weight to volume is the strongest cost material

Nonferrous metals

• Contain no iron include cooper, aluminum, and lead are easily used in building construction
  • Aluminum
    • Used in forming hard and like alloys
    • Extruded and sheet forms for building
  • Copper
    • Alloys and in the production of cooper piping.
  • lead
    • Isolation, radiation shielding.

Wood

• Offers stablility, durability and Lightweight easy workability.
• Used for many construction purposes
  • Generally used for furniture and joinery
• Two types
  • Hardwood, Maple & Walnut are a tree the drops leaves used for surface paneling in the winter.
  • Softwoods cedar Includes evergreens and redwood

Lumber

• Classification is based off of what type for size for a certain grade.
  • Softwood timber for example is good for building purposes
    • Classified as Yard Lumber
      • Boards -Less than 2” thick x 2
        • Graded for appearance over strength
      • Dimension Lumber
        • 2 - 4"" thick, 2” or wider
        • Graded for strength
    • Timbers
      • at least 5” thick
    • Factor and Shop Lumber -Used to build doors and windows

Wood Panel Products as Materials used in Architecture

• Used for panels and plywoods -Plywood - -common durability made of 3 to 10 sheets or layers with moisture -Used for shuttering to furniture -Alternative is 90 degrees - Particleboard - Also known as chipboard and low density board – Wood chips with synthetic resin

Other Wood products

• Oriented strand board thin layers that are mixed with glue and are bonded together -Waferboard is wood that is random where directions panel strength is equal to one direction

Glass

• Used for thermal insulation
• chemically inert, transparent, hard, and brittle material is found in many forms
• Foamed or cellular glass is used as thermal insulation.

Plastics

• Chemically produced substance can be used to replicate wood that is resistant to corrosion and mold – Used for insulation and door frames and accessories - Thermoplastic are easy to reuse by reheat and can mold over. - Examples: plastic bags
• Thermoset Plastic
  • Are unable to be changed because they have been reused and can expose to outside heat or cold that is why it's also used in heating vents or electricity.