Alpha breathing

EVOCATION

Ceramic tiles• ceramic tile is tile made of clay

Characteristics of Ceramic tiles• Water absorption• Durability• Not affected by oxygen• Abrasion resistance• Impact resistance• Breaking strength• Chemical resistance - resistant to almost all acids,

alkalies,

Uses of Ceramic tiles

• used almost everywhere- on walls, floors, ceilings, fireplaces, in murals, and as an exterior cladding on buildings.

Timbers• Wood suitable for building or engineering

purposes

• Applied to trees measuring not less than 0.6m in girth.

Characteristics of Soft timber

• Light in weight• Light in colour• It is resinous• It has straight fibres• It has distinct annual rings• Comparatively weak• It can be split easily

Characteristics of hard timber

Heavy in weightDark in colourNon-resinousClose grainedDoes not show clear annual ringStrongDurable Eg. Sal Teak Etc.,

Uses of timber• Used for doors & windows, roofing materials, etc.,• For formwork of cement concrete, scaffolding, etc.,• For making railway coach wagons.• For making furniture, agricultural, musical

instruments and sports goods.• For making railway sleepers, packing cases, etc.,• Used for temporary bridges & boat construction.

Formwork

scaffolding

railway coachwagons, packing case

Cement

• mixture of burned (at high temp.) calcareous & argillaceous material.

• Calcined product is called clinker• Clinker + gypsum- pulverised to fine powder – cement.

Properties of cement1. It should be uniform in colour2. Feel uniform, cool when touched and should sink in water3. Free from lumps4. Cement mortar should have a compressive strength of 11.5 N/mm2 &5. Tensile strength of 2N/mm2 at the age of 3 days.6. At the age of 7 days compressive strength should be 17.5 N/mm2 & tensile

strength not should be <2.5 N/mm2

7. % of alumina and iron oxide should not be less than 0.668. When ignited should not loose 4% of its weight.9. Sulphur content should not be > 1.5%10.Weight of magnesia should not exceed 5%11.Specific surface should not be less than 2250 mm2/mg12. Initial setting time should be < 30 minutes and not > 45 minutes & final

setting time shall be around 10 Hours13.Expansion should not be > 10 mm

Uses of cement• Cement mortar used for masonry work, plastering,

pointing & joints of pipes, etc.,

• Binding material in concrete

• Construction of bridges, culverts, dams, tunnels, etc., needs cement.

• Manufacture of precast piles, pipes, garden sheets, etc.,

• Underwater construction – quick setting cement.

• Floor finishing – White & coloured cements

• Repair works of cracks – Expansive cements

quick setting cement

Types of cement• Quick setting cement• Low heat cement• High alumina cement• Expanding cement• Rapid hardening cement• Acid resistant cement• Sulphate resisting cement• White cement• Coloured cement• Portland puzzolana cement

Aggregates• Occupy 70-75% of the total volume of

concrete

• Inert material

Aggregates

• Coarse aggregate • e.g. Gravel – >

4.75mm

• Fine aggregate • e.g. sand – Between

4.75 & 0.075mm

• Silt – varies from 0.02mm – 0.075mm

• Clay – <0.02mm

Characteristics of aggregates• cheap fillers

• hard material

• provide for volume stability

• reduce volume changes

• provide abrasion resistance

Uses of aggregates

• Aggregates are used in construction to provide drainage, fill voids, protect pipes, and to provide hard surfaces.

• They are also used in water filtration and sewage treatment processes.

• In concrete it provides a rigid skeletal structure and to reduce the space occupied by the cement paste.

• Railway ballast generally consists of a tough igneous rock, such as granite, with large (40-50 mm size) angular pieces that lock together. Because of the way igneous rock is formed it is highly resistant to pressure and does not break easily.

Concrete

• Mixture of (cement + sand + crushed rock + water)

• Types: – Light weight

– High density

– Polymer

Characteristics of concrete• It has high compressive strength.• Free from corrosion• Hardens with age• Steel reinforcement is placed to take up

tensile stress (RCC)• Shrinkage occurs when it hardens• It is porous due to the presence of voids• Has hard surface to resist abrasion.

Uses of concrete

• Used for construction of RCC flat-roof slabs, bridges, dams, chimneys etc.,

• Coloured concrete – Ornamental finishes in buildings, park lanes, separating lines of road surfaces, etc.,

• Light weight concrete – multi-storeyed constructions• No-fines concrete – cast-in-situ external load bearing walls of

single & multi-storey houses, retaining walls, etc.,• Sleepers in railways• Prestressed concrete in bridges.• Nuclear reactors – High shielding capacity for radioactivity.

PUZZELS• Which letter is midway between the letter two letters

below the letter immediately to the left of the letter G, and the letter three letters above the letter immediately to the right of the letter V?

• Ans: L

• What number should replace the question mark?

• Ans: 8. Sol.Each number in the segment at the bottom is the sum of the four numbers in the sections either side. Thus 8 + 3 + 4 + 3 = 18

• Mind map

Assessment

• The initial setting time of cement should not be less than _____ minutes.

(a)10 (b) 20 (c) 30 (d) 40

• The expansion of cement should not be greater than ____ when soundness test is conducted  

(a) 4 mm (b) 6 mm (c) 8 mm (d) 10 mm

• Cement mortar at the age of three days should have a compressive

strength of  

(a) 11.5 N/mm2 (b) 12.5 N/mm2 (c) 13.5 N/mm2 (d) 15 N/mm2