HND Civil Engineering

Construction Materials & Testing (DW5C34)

To be used with the following handout:

"Manufacture & Properties of Materials"

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Timber & Brick Presentation

What you will hopefully learn from this PowerPoint…

Basics of Raw Materials (Timber & Brick),

Manufacturing Processes and issues,

Testing procedures.

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Physical & Mechanical Properties

Physical Properties

Describes the materials’ natural state

Solid, liquid or gas.

Shape, angle, area.

Texture.

Colour.

Odour.

Melting/boiling point.

Absorption.

Density.

Conductance.

Just so you know…

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Physical & Mechanical Properties

Mechanical Properties

Describes the materials’ properties and strength.

Tensile

Strength

Compressive

Strength

Flexural

Strength

Torsional

Strength

Shear

Strength

Just so you know…

Timber

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Handout Pages 45-53

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Timber Origins

Have a brief read in your own time

Manufacture & Properties of Materials

Handout- Page 47

Mahogany Oak Ash

Type 1) Hardwoods

Type 2) Softwoods

Fir Cedar Pine

Most commonly used

Most commonly used

Hardwood Hardwoods come from deciduous trees. i.e. trees that are broad-leaved and that shed in the autumn months. Softwood Softwoods come from coniferous trees. i.e. evergreen, needle-leaved, cone-bearing trees.

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Timber Origins

Types of Wood

Definition

Timber Origins

Rays

Earlywood

Latewood

Softwood Cellular Structure

Softwood Tree Cross-Section

Earlywood

Latewood Rays

Growth Ring

Pith

Heartwood

Vascular

Cambium

Outer

Bark

Inner

Bark

Secondary Phloem

Cork Cambium

Sapwood

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Timber Origins

Key points

Earlywood

Latewood Rays

Heartwood

Sapwood

Vascular

Cambium

Outer

Bark

Inner

Bark

Secondary Phloem

Cork Cambium

Heartwood essentially supports the weight of the tree. It is composed of dead cells and is

usually older, darker, drier and harder that the living Sapwood.

Sapwood is inferior in terms of durability due to its moisture content and presence of starch

which attracts insects and provides food for fungi. Sapwood is very porous which allows the

tree to naturally transport sap internally.

The cellular structure of the Earlywood and Latewood illustrates why timber is a popular

choice within construction, due to the cementing “key” that the structure creates when

combined with glue and adhesive.

Earlywood

Latewood

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Timber Manufacture

Timber Conversion

Through by Through

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Timber Conversion The alternative

Timber Manufacture

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Seasoning

Timber Treatment

Seasoning- is the process of reducing the moisture content (MC) of timber to ensure it

is fit for the intended purpose

Why do we season timber…

Seasoned timber is stronger.

Seasoned timber is easier to work with.

Every time the MC reduces, timber can shrink.

Reduces the tendencies to warp, split or shake.

Seasoned timber lighter will be stronger and more reliable.

Timber must be below 20% MC to reduce the chances of Dry Rot.

Removal of sap makes it less likely to attract fungi and wood parasites.

Lower the MC, the easier to provide finish i.e. paint, varnish, etc.

*After seasoning both Heartwood & Sapwood have very little difference between them in terms of density and strength.

Preservative

Wood preservation- pressure or thermal impregnation of chemicals into wood to provide

effective long-term resistance to attack by fungi, bacteria, insects, and marine borers. There

are two forms of preservative, oil based or water based.

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Seasoning

There are two methods of seasoning; Air (Natural) and Kiln (Artificial).

Air Seasoning Kiln Seasoning

Timber Treatment

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Timber Testing

Compression Test

Bend Test

Compressive

Strength

Flexural

Strength

Video

Video

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Timber Testing

Screw Pull Out test

Tensile

Strength

Tensile Test

Brick & Blockwork

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Handout Pages 37-44

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Brick & Blockword Origins

Clay bricks are constructed from a mixture of silica (SiO2), alumina (Al2O3), limestone/chalk

(CaCO3), iron oxide (Fe2O3), and magnesia (MgO).

Bricks date back several thousands of years, first established in hot climates- where the

above mixture was moulded and dried in the sun.

Later on during Roman times, it was established that if this clay mixture was heated to a

high temperature, then the bricks could be produced much stronger.

This basic principle as not fundamentally changed over the years. However, obviously more

autonomous methods of manufacturing are utilised.

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Clay Bricks

Sand Lime Bricks Concrete Blocks

Clay Bricks can be divided into 4 categories:

Common brick,

Facing brick,

Load Bearing and,

Engineering.

Both Sand Lime and Concrete are

classified according to their strength.

Brick & Blockword Origins

Types of Bricks

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Brick & Blockword Manufacture

Brick Manufacturing

Manufacture & Properties of Materials Handout- Page 39-40

illustrates this process in a written formal.

Video

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Brick & Blockword Manufacture

Lime and sand are mixed together with a very small amount of water, this is then placed into

a mould and subjected to large amounts of pressure to form the bricks.

These bricks are then transported to large pressure cookers (autoclaves), and cooked using

steam for a period of seven to eight hours. This process causes the sand and lime to

combine chemically, and once cooled down they are ready for use.

Sand Lime Manufacture

Concrete Blockwork Manufacture

Appropriate mixes of concrete with various aggregates and additives are mixed thoroughly,

and then placed into the required mould and allowed to set.

These moulds are then transported to large pressure cookers (autoclaves), and cooked

using steam for a period of five to ten hours- before being allowed to cool down.

More Info

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Brick & Blockword Issues

Simply put, a Sulphate attack is when

horizontal cracking of the mortar joint appears

and as it progresses it causes expansion and

destruction of the mortar, leading ultimately to

structural failure.

Sulphate Attack

Efflorescence

Efflorescence is when the the face of the

brickwork is subjected to salt deposits, caused

by natural impurities within the brick. Due to its

effect on the brick work finish, it should be

avoided at all costs. However, it will remove

itself naturally over time- it is also worth

mentioning that this does not damage the

brick work nor lead to remedial works.

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Brick & Blockword Tests

Compression testing of bricks is commonly used as it involved testing the bricks in the

manner in which they will be used within the structure.

Due to the likely differences in moisture content with each brick, each of the testing bricks

will be saturated with water for 24 hours prior to testing. (10 bricks should be tested)

To remove any possible effects due to brick imperfections, 3mm plywood sheets are placed

above and below the brick during the testing phase.

Strength Test

Water Absorption

Various methods of testing, however the testing mainly consists of boiling or subjecting oven

dried bricks for a period of time to assess how much water the brick will absorb. Bricks will

be weighed before and after the test to calculate the absorption.

Soluble Salts

A test sample (usually 10 or so bricks) are removed from each batch. These bricks are then

crushed into a powder and assessed for chemical analysis to establish how much solvable

salt content is present.

Video

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Materials and Testing

Any Questions…