Construction Materials and Equipment Ch-1 part 2&3 PDF

ODA BULTUM UNIVERSITY Institute of Technology Department of civil Engineering CONSTRUCTION MATERIALS AND EQUIPMENT (CENG-2081 ) By: Neway Y.(MSc.) October,2024  CHAPTER 1 STONE-BRICKS-CONCRETE BLOCKS 2. Bricks ...

ODA BULTUM UNIVERSITY Institute of Technology Department of civil Engineering CONSTRUCTION MATERIALS AND EQUIPMENT (CENG-2081 ) By: Neway Y.(MSc.) October,2024  CHAPTER 1 STONE-BRICKS-CONCRETE BLOCKS 2. Bricks  Introduction  One of the oldest building material brick continues to be a most popular and leading construction material because of being cheap, durable and easy to handle and work with.  Clay bricks are used for building-up exterior and interior walls, partitions, piers, footings and other load bearing structures.  Introduction  A brick is rectangular in shape and of size that can be conveniently handled with one hand.  Brick may be made of burnt clay or mixture of sand and lime or of Portland cement concrete.  Clay bricks are commonly used since these are economical and easily available.  Introduction Size of brick 1. Standard size 2. Nominal size or Size of brick along with mortar  Introduction  The length, width and height of a brick are interrelated as below:  Length of brick = 2 x width of brick + thickness of mortar  Height of brick = width of brick  Introduction  Size of a standard brick (also known as modular brick) should be 19 x 9 x 9 cm and 19 x 9 x4 cm.  When placed in masonry the 19 x 9 x 9 cm brick with mortar becomes 20 x 10 x 10 cm. as field bricks.  Weight of such a brick is 3.0 kg. An indent called frog, 1-2 cm deep.  Composition of Brick  The following are the constituents of good brick earth: Silica (SiO2)- 50-60% Alumina (Al2O3)- 20-30% Lime (CaO)- 4-5% Iron oxide (Fe2O3)- 5-6% Magnesia (MgO)-1%  Manufacturing of bricks 1.Preparation of 2. Moulding 3. Drying 4.Burning Brick Earth  Manufacturing of bricks 1. Preparation of Brick Earth  It consists of the following operations. A. Unsoiling: top 200mm of soil is thrown and is not as it consists of majority of impurities in it  Manufacturing of bricks 1. Preparation of Brick Earth B. Digging:  The clay is then dug out from the ground.  It is spread on the levelled ground.  The height of heaps of clay is about 60cm to 120 cm  Manufacturing of bricks 1. Preparation of Brick Earth C.Cleaning  The clay which is used for preparing bricks should be cleaned of stones, pebbles and vegetable matter, etc.  If the impurities are present in excess the clay is subjected to washing and screening.  Manufacturing of bricks 1. Preparation of Brick Earth D.Weathering:  The clay is exposed to weather from few weeks to full season.  Subjecting the soil to exposed condition of weather such as rain, heat by sun, snow, wind, etc. is known as weathering.  Alternate wetting, cooling, heating and drying.  Manufacturing of bricks 1. Preparation of Brick Earth E. Blending:  The clay is made loose and any ingredient to be added to it, is spread out at its top.  It is carried out by taking small portion of clay every time and by turning it up and down in vertical direction.  For large quantity of soil machines may be adopted.  Manufacturing of bricks 1. Preparation of Brick Earth F. Tempering  In the process of tempering the clay is brought to a proper degree of hardness and it is made fit for the next operation of moulding.  The water in required quantity is added to Clay and just under the feet of men or cattle.  The tempering makes the clay into a homogeneous mass.  Manufacturing of bricks 2. Moulding  It is a process of giving a required shape to the brick from the prepared brick earth.  During moulding a mark of depth 10-20 mm is placed over the surface of the brick that is termed as frog mark, which serves following two purpose: i) Trade name of the manufacturer. ii) It acts a key for mortar when the layer of bricks is placed over it.  Manufacturing of bricks 2. Moulding  The molding can done in two ways  Hand moulding  Machine moulding  Manufacturing of bricks 2. Moulding  Hand moulding  The bricks are moulded by using manpower.  It is adopted where the main power is cheaper.  It is suitable for small scale production.  Manufacturing of bricks 2. Moulding Types of mould  Based on the material in which the mould is made it is classified as:  Wooden mould  Steel mould  Manufacturing of bricks 2. Moulding Wooden mould  It should be prepared from well- seasoned wood.  The longer sides are kept slightly projecting to serve as handles.  The wood should have smooth faces.  Manufacturing of bricks 2. Moulding Steel mould  Steel mould are made by the Steel plates or channels.  The thickness of Steel mould is generally 6mm.  The Steel moulds are more durable than wooden moulds.  It can produce the bricks of uniform sizes when compared to wooden moulds.  Manufacturing of bricks 2. Moulding The bricks prepared by hand moulding are of two types;  Ground moulded bricks  Table moulded bricks  Manufacturing of bricks 2. Moulding Ground moulded bricks  This type of bricks is hand moulded and placed on ground itself  Usually the ground moulded bricks are rough at the bottom surface. Hence it is placed on sprinkling sand it is also called as sand moulded bricks  A brick moulder can mould about 750 bricks per day  Manufacturing of bricks 2. Moulding Table moulded bricks  This type of bricks are hand molded and it is placed on table.  The process of moulding this breaks is just similar to ground moulded bricks  Generally the table moulded bricks are having smooth surface at bottom.  Manufacturing of bricks 2. Moulding Machine Molding  Machine moulded bricks are usually wire cut and pressed bricks.  It having smooth surfaces, regular shape, Sharp edges and corners.  They are heavier and stronger than ordinary hand moulded bricks  The Machines moulded bricks are also of two types:  Plastic clay machines  Dry clay machines  Manufacturing of bricks 2. Moulding Plastic clay machines  Water is added to make the clay in plastic state.  This machine consist of rectangular opening of size equal to width of the bricks  The pug clay is placed in the machine and it comes out through the opening, it is cut into to strips bye wires fixed in frames.  Arrangement is made in such a way that, the wire cutting is equal to the length of bricks.  Manufacturing of bricks 2. Moulding Dry clay machines  In this machines the strong clay is first converted into powdered form.  A small quantity of water is then added to get a plastic paste.  Paste is placed in mould and pressed by the machine to form hard and well-shaped bricks.  Manufacturing of bricks 3. Drying  Drying is usually done by placing the bricks in sheds with open sides so as to ensure free circulation of air and protection from bad weather and rains.  The bricks are allowed to dry till they are left with 5 to 7 % moisture content.  The drying period usually varies from 7 to 14 days.  During drying, bricks are always placed along their edge and never placed along there face, in order to speed up the process of drying.  Manufacturing of bricks 3. Drying  The moulded bricks are dried because of the following reasons.  If damp bricks or green bricks are directly taken to burning then, they are likely to be cracked and distorted.  To remove maximum moisture from the brick.  To save time and fuel during burning.  To increase the strength of raw bricks so that they can be handled and stacked in greater heights.  Manufacturing of bricks 4. Burning  Burning impacts strength and hardness to the bricks, it makes them dense and durable.  Burning should be done properly  Over burnt- Brittle/easily broken  Under burnt- Soft/unable to carry designed load  Burning of the bricks is carried out at 1100°C at which silica and lime fuse with each other thereby imparting strength to the bricks.  Manufacturing of bricks 4. Burning Burning occurs in 3 stages: a) Dehydration/Water smoking stage (400 – 650°C)  Water from pores is driven off  Some of carbonaceous matter is burnt b) Oxidation Period(650-900°C)  Remaining carbon is burnt  Ferrous Iron is converted into Ferric Iron  Sand is added to allow escaping of gases c) Vitrification(900 - 1100°C)  To convert the mass into glass like substance  Manufacturing of bricks 4. Burning Bricks may be burnt by two distinct methods given below.  Clamp burning  Kiln burning  Manufacturing of bricks 4. Burning a) Burning of Bricks in Clamps  Trapezoidal shape  End raised at 15° c from ground level  A brick wall in mud is at the shorter end.  Alternate layers of raw bricks and fuels.  Fuel---grass, rice husk ash, wood, cow dung, coal dust etc  Air circulation spaces provided  Total height of clamp =3-4m  Manufacturing of bricks 4. Burning a) Burning of Bricks in Clamps  Burning period = 1-2 months  Cooling period = 1-2 months  Burnt bricks are taken out from the clamp  Manufacturing of bricks 4. Burning b) Burning of Bricks in Kilns  Kilns are large sized oven to burn bricks.  Fire period = 48 to 60 hours  Cool period = 12 days  Supply of the bricks from these kilns are classified as-  Intermittent Kilns.  Continuous Kilns.  Manufacturing of bricks 4. Burning Intermittent Kilns.  They are also the periodic kind of kilns, because in such kilns only one process can take place at one time. Continuous Kilns  These kilns are called continuous because all the processes of loading, unloading, cooling, Heating, preheating take place simultaneously.  Classification of bricks Bricks can broadly be divided into two categories. I. Unburnt or sundried bricks II. Burnt bricks I. Unburnt or sundried bricks  Sun dried bricks  used only in the constructions of temporary and cheap structures.  Should not be used at places exposed to heavy rains.  Classification of bricks II. Burnt bricks  Used in construction works  They are classified into the following four categories. 1. First class bricks 2. Second class bricks 3. Third class bricks 4. Fourth class bricks  Classification of bricks A. First Class Bricks  Are table moulded and of standard shape.  The surface and edges are sharp, square, smooth and straight.  Good bricks and used for permanent works.  Classification of bricks B. Second Class Bricks  These bricks are ground molded and burnt in kilns.  The edges may not be sharp and uniform.  Commonly used for the construction of walls which are going to be plastered.  Classification of bricks C. Third Class Bricks  These bricks are ground moulded and burnt in clamps.  Used for unimportant and temporary structures and at places where rainfall is not heavy.  Classification of bricks D. Fourth Class Bricks  Over burnt bricks with irregular shape and dark color.  Used as aggregates for concrete in foundations, floors and roads.  Qualities of Good Brick I. Free from cracks and have sharp edges II. Uniform shape and should be of standard size. III.Should give clear ringing sound when struck each other. IV.Compact and free from voids. V. Bricks should not absorb water when soaked for 24 hours  1st class ---- max = 20% by weight  2nd class----max = 22% by weight VI.No impression when it is scratched with finger nail. VII.Low thermal conductivity and they should be sound proof  Qualities of Good Brick VIII.When dropped from 1m height-----should not break IX.When soaked in water for 24hours, should not show deposits of white salts when allowed to dry in shade. X. Crushing strength > 55kg/cm2  Test on Bricks  To know the quality of bricks the following tests can be performed. In these tests some are performed in laboratory and the rest are on field.  Compressive strength test  Water absorption test  Efflorescence test and  Hardness Test  Soundness Test  Structure Test  Test on Bricks 1. Compressive strength test  This test determines the compressive strength (also called crushing strength) of a brick.  Generally, 5 brick specimens are taken to the laboratory for testing.  Each brick is tested one by one.  A brick specimen is placed in a crushing machine.  Pressure is applied gradually until the brick breaks.  The maximum pressure at which the brick breaks is recorded as its crushing strength.  After testing all five specimens, the average result is calculated to determine the brick's compressive/crushing strength.  Test on Bricks 1. Compressive strength test  Test on Bricks 2. Water absorption test  First, weigh the bricks when they are dry (W1).  Immerse the bricks in fresh water for 24 hours.  After 24 hours, take the bricks out of the water and wipe them with a cloth to remove excess water and Weigh the bricks again while they are wet (W2).  Calculate the percentage of water absorption using the formula: 𝑾𝒂𝒕𝒆𝒓 𝑨𝒃𝒔𝒐𝒓𝒑𝒕𝒊𝒐𝒏(%) = (𝑾𝟐 − 𝑾𝟏)/𝑾𝟏 ∗ 100  The less water a brick absorbs, the better its quality.  A good quality brick should not absorb more than 20% of its dry weight in water.  Test on Bricks 2. Water absorption test  Test on Bricks 3. Efflorescence test  The presence of alkalies in bricks is harmful as they absorb moisture and form a grey or white layer on the brick surface.  This test is conducted to detect the presence of alkalies in bricks.  Test on Bricks 3. Efflorescence test Test procedure  Immerse a brick in fresh water for 24 hours.  After immersion, take the brick out and allow it to dry in the shade.  If no whitish layer appears on the surface, the brick is free from alkalies.  If a whitish layer covers about 10% of the surface, the alkalies are present, but within acceptable limits.  If the whitish layer covers about 50% of the surface, the presence of alkalies is moderate.  If the whitish layer covers more than 50% of the surface, the brick is severely affected by alkalies.  Test on Bricks 4. Hardness test  In this test a scratch is made on brick surface with a hard thing.  If that doesn’t left any impression on brick then that is good quality brick. 5. Soundness test  In this test two bricks are held by both hands and struck with one another  If the bricks give clear metallic ringing sound and don’t break then those are good quality bricks.  Test on Bricks 6. Structure Test  In this test a brick is broken or a broken brick is collected and closely observed. If there are any flows, cracks or holes present on that broken face then that isn’t good quality brick 3. Concrete blocks  Definition & Use  Concrete is a composite material obtained artificially by hardening of the mixture of cement, aggregate and water.  Block: are a masonry unit made from a different material mixture and have a definite shape.  Concrete blocks are produced by concrete block making machines.  Definition & Use  Concrete block construction is gaining importance in developing countries, even in low-cost housing, and has become a valid alternative to fired clay bricks and other common construction materials. Uses  Concrete blocks are used as a masonry unit in wall construction and currently it is also used for slabs (ribbed slab).  Definition & Use Uses HCB wall Ribbed slab HCB  Classification of concrete block I. Solid blocks:- have no cavities, or have voids amounting to not more than 25 % of the gross cross-sectional area. II. Cellular blocks:- have one or more voids with one bed.  Classification of concrete block III. Hollow blocks:-  These are the most common types of concrete blocks.  Different types and sizes of hollow concrete blocks for wall construction can be produced.  The most common type of a HCB is the one with two openings.  The total void area can amount to 50% of the gross cross- sectional area. Types of Hollow Concrete Blocks  Stretcher block  Corner block  Pillar block  Jamb block  Partition block  Lintel block  Brick block  Bull nose block  Types of Hollow Concrete Blocks Concrete Stretcher block  Stretcher blocks are widely used concrete hollow blocks in construction.  They are laid with their length parallel to the face of the wall.  Types of Hollow Concrete Blocks Concrete Corner block  Corner blocks are used at the ends or corners of masonry.  The ends may be window or door openings etc.  They are arranged in a manner that their plane end visible to the outside and other end is locked with the stretcher block.  Types of Hollow Concrete Blocks Partition Concrete Block  Designed for non-load-bearing partition walls, which are interior walls that divide spaces within a building.  These blocks are thinner compared to standard blocks and have larger height than its width.  Used extensively in the construction of interior partition walls where load-bearing capacity is not required, offering a lightweight and easy-to-install option.  Advantage of concrete block  The use of hollow concrete blocks has several advantages:  If lightweight aggregate is used, can be very light.  They require far less mortar than solid blocks and construction of walls is easier and quicker.  The voids can be filled with steel bars and concrete, achieving high seismic resistance.  The air-space provides good thermal insulation.  The cavities can be used as ducts for electrical installation and plumbing. Materials For Concrete Blocks  Materials For Concrete Blocks Materials  Cement  Aggregate  Water Cement  OPC, Portland blast furnace slag, sulfate resisting.  It is used to react with the water forming a plastic mass when the concrete is fresh and a solid mass when the concrete is hard.  Materials For Concrete Blocks Aggregate  The maximum particle size of coarse aggregate is 13mm(10 mm ).  Rounded stones produce a concrete that flows more easily than angular particles but the latter give high strength.  Used to:  Provide an inert mineral base for the cement paste to bind together.  Reduce the volume changes resulting from the setting and hardening process and from moisture changes in the paste.  Materials For Concrete Blocks Water  Enables the chemical reactions which cause setting and hardening to proceed.  Lubricate the mixture of aggregates and cement.  Production Process  The process of manufacture of cement concrete blocks involving the following 4 stages.  Proportioning  Mixing  Compacting  Curing  Production Process 1. Proportioning  It is the determination of suitable amounts of raw material needed to produce concrete blocks of desired quality. 2. Mixing  The goal of mixing is to combine the raw materials into a homogeneous concrete mix that ensures uniformity in the final product.  Proper mixing is crucial for achieving the desired strength, workability, and durability of the concrete blocks.  Production Process 3. Compacting  Compacting involves consolidating the concrete mix into the molds to remove air bubbles and achieve the desired density and strength. Block making Machines ‘Egg-laying‘ machine Automatic stationary machines  Production Process 4. Curing  Curing is the process of maintaining moisture and temperature conditions to ensure the concrete reaches its desired strength and durability.  Proper curing is essential for at least 7 to 14 days Production Process Production Process  Tests on Concrete Masonry Block Units  Different tests are conducted on concrete masonry unit to satisfy the all requirements.  Concrete Blocks of same mix shall be taken and divide them as follows to conduct the following tests.  Dimension measurement  Compressive strength of block Dimension Measurement  All blocks should be measured to their length, width and height with steel scale.  Tests on Concrete Masonry Block Units Commonly used dimension of HCB are tabulated below  Tests on Concrete Masonry Block Units Compressive Strength  The compressive strength of a concrete masonry unit shall be taken as the maximum load in Newton’s divided by the gross cross section area of the unit in square millimeter. According to Ethiopian Standard, the minimum compressive strength of Hollow Concrete THANK YOU