Monday, April 17, 2017

Types of Lime Used in Construction

Types of Lime Used in Construction


It is an important binding material used in building construction. Lime has been used as the material of construction from ancient time. When it is mixed with sand it provides lime mortar and when mixed with sand and coarse aggregate, it forms lime concrete.
Types of Lime Used in Construction

Types of Limes and their Properties

The limes are classified as fat lime, hydraulic lime and poor lime:

Fat lime:

It is composed of 95 percentage of calcium oxide. When water is added, it slakes
vigorously and its volume increases to 2 to 2 ¹/₂ times. It is white in colour. Its properties are:

 hardens slowly
 has high degree of plasticity
 sets slowly in the presence of air
 white in colour
 slakes vigorously

Hydraulic lime:

It contains clay and ferrous oxide. Depending upon the percentage of clay present, the hydraulic lime is divided into the following three types:

Feebly hydraulic lime (5 to 10% clay content)
Moderately hydraulic lime (11 to 20% clay content)
Eminently hydraulic lime (21 to 30% clay content)

The properties of hydraulic limes are:

Sets under water 
Colour is not perfectly white
Forms a thin paste with water and do not dissolve in water.
Its binding property improves if its fine powder is mixed with sand and kept in the form of heap for a week, before using.

Poor lime:

It contains more than 30% clay. Its colour is muddy. It has poor binding property. The mortar made with such lime is used for inferior works.

IS 712-1973 classifies lime as class A, B, C, D and E.

 Class A Lime: It is predominently hydraulic lime. It is normally supplied as hydrated lime and is commonly used for structural works.

 Class B Lime: It contains both hydraulic lime and fat lime. It is supplied as hydrated lime or as quick lime. It is used for making mortar for masonry works.

 Class C Lime: It is predominently fat lime, supplied both as quick lime and fat lime. It is used for finishing coat in plastering and for white washing.

 Class D Lime: This lime contains large quantity of magnesium oxide and is similar to fat lime. This is also commonly used for white washing and for finishing coat in plastering.

✖ Class E Lime: It is an impure lime stone, known as kankar. It is available in modular and block form. It is supplied as hydrated lime. It is commonly used for masonry mortar.

Tests on Limestones

The following practical tests are made on limestones to determine their suitability:

 Physical tests
 Heat test
✒ Chemical test
✒ Ball test

 Physical tests ; Pure limestone is white in colour. Hydraulic limestones are bluish grey, brown or are having dark colours. The hydraulic lime gives out earthy smell. They are having clayey taste. The presence of lumps give indication of quick lime and unburnt lime stones.

 Heat test ; A piece of dry stone weighing W1 is heated in an open fire for few hours. If weight of sample after cooling is W2, the loss of weight is W2 – W1. The loss of weight indicates the amount of carbon dioxide. From this the amount of calcium carbonate in limestone can be worked out.

 Chemical test ; A teaspoon full of lime is placed in a test tube and dilute hydrochloric acid is poured in it. The content is stirred and the test tube is kept in the stand for 24 hours. Vigourous effervescence and less residue indicates pure limestone. If effervescence is less and residue is more it indicates impure limestone.

If thick gel is formed and after test tube is held upside down it is possible to identify class of lime as indicated below:

Class A lime, if gel do not flow.
Class B lime, if gel tends to flow down.
Class C lime, if there is no gel formation.

 Ball test ; This test is conducted to identify whether the lime belongs to class C or to class B. By adding sufficient water about 40 mm size lime balls are made and they are left undisturbed for six hours. Then the balls are placed in a basin of water. If within minutes slow expansion and slow disintegration starts it indicates class C lime. If there is little or no expansion, but only cracks appear it belongs to class B lime.

Uses of Lime

The following are the uses of lime in civil works:


 For white washing.
 For making mortar for masonry works and plastering.
 To produce lime sand bricks.
 For soil stabilization.
 As a refractory material for lining open hearth furnaces.
 For making cement. 
Types of Lime Used in Construction

Waiting For Next Lesson, Next Lesson about CEMENT...

Saturday, April 15, 2017

Bricks and Types of Bricks

 Bricks and Types of Bricks

Brick is obtained by moulding good clay into a block, which is dried and then burnt. This is the oldest building block to replace stone. Manufacture of brick started with hand moulding, sun drying and burning in clamps. A considerable amount of technological development has taken place with better knowledge about to properties of raw materials, better machinaries and improved techniques of moulding drying and burning.

The size of the bricks are of 90 mm x 90 mm x 90 mm and 190 mm x 90 mm x 40 mm. With mortar joints, the size of these bricks are taken as 200 mm x 100 mm x 100 mm and 200 mm x 100 mm x 50 mm. However the old  size of 8 ³/₄" × 4 ¹/₂" × 2 ⁵/₈"  giving a masonary Size of 9" x 4 ¹/₂ 9" x 4 ¹/₂" x 3" is still Commonly used in india. 

 Types of Bricks

Bricks may be broadly classified as:

1. Fire bricks
2. Paving bricks
3. Building bricks
4. Special bricks

1. Fire bricks ; These bricks are specially made to withstand furnace temperature. Silica bricks belong to this category

2. Paving bricks ; These are vitrified bricks and are used as pavers.

3. Building bricks ; These bricks are used for the construction of walls.

4. Special bricks ; These bricks are different from the commonly used building bricks with respect to their shape and the purpose for which they are made. Some of such bricks are listed below:

⒜ Specially shaped bricks
⒝ Facing bricks
⒞ Perforated building bricks
⒟ Burnt clay hollow bricks
⒠ Sewer bricks
⒡ Acid resistant bricks

⒜ Specially shaped bricks ; Bricks of special shapes are manufactured to meet the requirements of different situations. Some of them are shown in Below image.

 Facing bricks ; These bricks are used in the outer face of masonry. Once these bricks are provided, plastering is not required. The standard size of these bricks are 190 × 90 × 90 mm or 190 × 90 × 40 mm.

⒞ Perforated building bricks ; These bricks are manufactured with area of perforation of 30 to 45 per cent. The area of each perforation should not exceed 500 mm². The perforation should be uniformly distributed over the surface. They are manufactured in the size 190 × 190 × 90 mm and 290 × 90 × 90 mm.

⒟ Burnt clay hollow bricks ; Below image shows a burnt clay hollow brick. They are light in weight. They are used for the construction of partition walls. They provide good thermal Insulation to buildings. They are manufactured in the sizes 190 × 190 × 90 mm, 290 × 90 × 90 mm and 290 × 140 × 90 mm. The thickness of any shell should not be less than 11 mm and that of any web not less than 8 mm.

⒠ Sewer bricks ; These bricks are used for the construction of sewage lines. They are manufactured from surface clay, fire clay shale or with the combination of these. They are manufactured in the sizes 190 × 90 × 90 mm and 190 × 90 × 40 mm. The average strength of these bricks should be a minimum of 17.5 N/mm² . The water absorption should not be more than 10 per cent.

⒡ Acid resistant bricks ; These bricks are used for floorings likely to be subjected to acid attacks, lining of chambers in chemical plants, lining of sewers carrying industrial wastes etc. These bricks are made of clay or shale of suitable composition with low lime and iron content, flint or sand and vitrified at high temperature in a ceramic kiln.

 Properties of Bricks

The following are the required properties of good bricks:

Color ; Color should be uniform and bright.

Shape ; Bricks should have plane faces. They should have sharp and true right angled corners.

Size ; Bricks should be of standard sizes as prescribed by codes.

Texure ; They should possess fine, dense and uniform texture. They should not possess fissures, cavities, loose grit and unburnt lime.

Soundness ; When struck with hammer or with another brick, it should produce metallic sound.

Hardness ; Finger scratching should not produce any impression on the brick.

Strength ; Crushing strength of brick should not be less than 3.5 N/mm². A field test for strength is that when dropped from a height of 0.9 m to 1.0 mm on a hard ground, the brick should not break into pieces.

Water Absorption ; After immercing the brick in water for 24 hours, water absorption should not be more than 20 per cent by weight. For class-I works this limit is 15 per cent.

Efflorescence ; Bricks should not show white patches when soaked in water for 24 hours and then allowed to dry in shade. White patches are due to the presence of sulphate of calcium, magnesium and potassium. They keep the masonry permanently in damp and wet conditions.

Thermal Conductivity ; Bricks should have low thermal conductivity, so that buildings built with them are cool in summer and warm in winter.

Sound Insulation ; Heavier bricks are poor insulators of sound while light weight and hollow bricks provide good sound insulation.

Fire Resistance ; Fire resistance of bricks is usually good. In fact bricks are used to encase steel columns to protect them from fire.

 Tests on Bricks

The following laboratory tests may be conducted on the bricks to find their suitability:

Crushing strength
Shape and size

Crushing strength ; The brick specimen are immersed in water for 24 hours. The frog of the brick is filled flush with 1:3 cement mortar and the specimen is stored in damp jute bag for 24 hours and then immersed in clean water for 24 hours. The specimen is placed in compression testing machine with 6 mm plywood on top and bottom of it to get uniform load on the specimen. Then load is applied axially at a uniform rate of 14 N/mm². The crushing load is noted. Then the crushing strength is the ratio of crushing load to the area of brick loaded. Average of five specimen is taken as the crushing strength.

Absorption Test ; Brick specimen are weighed dry. Then they are immersed in water for a period of 24 hours. The specimen are taken out and wiped with cloth. The weight of each specimen in wet condition is determined. The difference in weight indicate the water absorbed. Then the percentage absorption is the ratio of water absorbed to dry weight multiplied by 100. The average of five specimen is taken. This value should not exceed 20 per cent.

Shape and size ; Bricks should be of standard size and edges should be truely rectangular with sharp edges. To check it, 20 bricks are selected at random and they are stacked along the length, along the width and then along the height. For the standard bricks of size 190 mm × 90 mm × 90 mm. IS code permits the following limits:

Lengthwise: 3680 to 3920 mm
Widthwise: 1740 to 1860 mm
Heightwise: 1740 to 1860 mm

The following field tests help in acertaining the good quality bricks:

uniformity in size
uniformity in colour
hardness test
sound test
strength test

uniformity in size ; A good brick should have rectangular plane surface and uniform in size. This check is made in the field by observation.

uniformity in colour ; A good brick will be having uniform colour throughout. This observation may be made before purchasing the brick.

structure ; A few bricks may be broken in the field and their cross-section observed. The section should be homogeneous, compact and free from defects such as holes and lumps.

hardness test ; For this a simple field test is scratch the brick with nail. If no impression is marked on the surface, the brick is sufficiently hard

sound test ; If two bricks are struck with each other they should produce clear ringing sound. The sound should not be dull.

Efflorescence ; The presence of alkalies in brick is not desirable because they form patches of gray powder by absorbing moisture. Hence to determine the presence of alkalies this test is performed as explained below:

Place the brick specimen in a glass dish containing water to a depth of 25 mm in a well ventilated room. After all the water is absorbed or evaporated again add water for a depth of 25 mm. After second evaporation observe the bricks for white/grey patches. The observation is reported as ‘nil’, ‘slight’, ‘moderate’, ‘heavy’ or serious to mean

Nil: No patches

Slight: 10% of area covered with deposits

Moderate: 10 to 50% area covered with deposit but unaccompanied by flaking of the surface.

Heavy: More than 50 per cent area covered with deposits but unaccompanied by flaking of the surface.

Serious: Heavy deposits of salt accompanied by flaking of the surface.

 Classification of Bricks Based on their Quality

The bricks used in construction are classified as:

⏎ First class bricks
 Second class bricks
 Third class bricks
 Fourth class bricks

First class bricks ; These bricks are of standard shape and size. They are burnt in kilns. They fulfill all desirable properties of bricks.

Second class bricks ; These bricks are ground moulded and burnt in kilns. The edges may not be sharp and uniform. The surface may be some what rough. Such bricks are commonly used for the construction of walls which are going to be plastered.

Third class bricks ; These bricks are ground moulded and burnt in clamps. Their edges are somewhat distorted. They produce dull sound when struck together. They are used for temporary and unimportant structures.

Fourth class bricks ; These are the over burnt bricks. They are dark in colour. The shape is irregular. They are used as aggregates for concrete in foundations, floors and roads.

 Uses of Bricks

 Bricks are used in the following civil works: 
 As building blocks.
 For lining of ovens, furnaces and chimneys.
 For protecting steel columns from fire.
 As aggregates in providing water proofing to R.C.C. roofs.
 For pavers for footpaths and cycle tracks.
 For lining sewer lines.

Bricks and Types of Bricks

Monday, April 3, 2017



Timber refers to wood used for construction works. In fact the word timber is derived from an old English word ‘Timbrian’ which means ‘to build’. A tree that yields good wood for construction is called 'Standing Timber'. After felling a tree, its branches are cut and its stem is roughly converted into pieces of suitable length, so that it can be transported to timber yard. This form of timber is known as rough timber. By sawing, rough timber is converted into various commercial sizes like planks, battens, posts, beams etc. Such form of timber is known as converted timber.

Timber was used as building material even by primitive man. Many ancient temples, palaces and bridges built with timber can be seen even today.

Classification of Timber

Various defects which are likely to occur in timber may be grouped into the following three:

1.) Due to natural forces.
2.) Due to defective seasoning and conversions.
3.) Due to attack by fungi and insects.

1.) Defects due to Natural Forces

The following defects are caused by natural forces:

✤ Knots
✤ Wind Cracks
✤ Shakes
✤ Upsets

When a tree grows, many of its branches fall and the stump of these branches in the trunk is covered. In the sawn pieces of timber the stump of fallen branches appear as knots. Knots are dark and hard pieces. Grains are distorted in this portion. Figure 1.9 shows some varieties of knots. If the knot is intact with surrounding wood, it is called live knot. If it is not held firmly it is dead knot.

 Wind Cracks
These are the cracks on the outside of a log due to the shrinkage of the exterior surface. They appear as shown in below picture.

✤ Shakes
The shakes are cracks in the timber which appear due to excessive heat, frost or twisting due to wind during the growth of a tree. Depending upon the shape and the positions shakes can be classified as star shake, cup shake, ring shakes and heart shakes.

✤ Upsets
Below picture shows a typical upset in a timber. This type of defect is due to excessive compression in the tree when it was young. Upset is an injury by crushing. This is also known as rupture.

2.) Defects due to Defective Seasoning and Conversion

If seasoning is not uniform, the converted timber may warp and twist in various directions. Sometimes honey combining and even cracks appear. This type of defects are more susceptible in case of kiln seasoning.

In the process of converting timber to commercial sizes and shapes the following types of defects are likely to airse: chip marks, torn grain etc.

3.) Defects due to Fungi and Insects Attack

Fungi are minute microscopic plant organism. They grow in wood if moisture content is more than 20°C and exposed to air. Due to fungi attack rotting of wood, takes place. Wood becomes weak and stains appear on it.

Beetles, marine borers and termites (white ants) are the insects which eat wood and weaken the timber. Some woods like teak have chemicals in their compositions and resist such attacks. Other woods are to be protected by chemical treatment.

Preservation of Timber

Preservation of timber means protecting timber from fungi and insects attack so that its life is increased. Timber is to be seasoned well before application of preservatives. The following are the widely used preservatives:

 Chemical salt

Hot coal tar is applied to timber with brush. The coating of tar protects the timber from the attack of fungi and insects. It is a cheapest way of protecting timber. Main disadvantage of this method of preservation is that appearance is not good after tar is applied it is not possible to apply other attractive paints. Hence tarring is made only for the unimportant structures like fence poles.

Two to three coats of oil paints are applied on clean surface of wood. The paint protects the timber from moisture. The paint is to be applied from time to time. Paint improves the appearance of the timber. Solignum paint is a special paint which protects the timber from the attack of termites.

 Chemical salt
These are the preservatives made by dissolving salts in water. The salts used are copper sulphate, masonry chloride, zinc chloride and sodium fluoride. After treating the timber with these chemical salt paints and varnishes can be applied to get good appearance.

✢ Creosote
Creosote oil is obtained by distillation of coal tar. The seasoned timber is kept in an air tight chamber and air is exhausted. Then creosote oil is pumped into the chamber at a pressure of
0.8 to 1.0 N/mm² at a temperature of 50°C. After 1 to 2 hours timber is taken
out of the chamber.

This preservative is developed by the Forest Research Institute, Dehradun. It consists of 1 part by weight of hydrated arsenic pentoxide (As₂O₅, 2 H₂O), 3 parts by weight of copper sulphate (CuSO₄⋅5 H₂O) and 4 parts by weight of potassium dichromate (K₂Cr₂O₇) or sodium dichromate (Na₂Cr₂O₇⋅2 H₂O). This preservative is available in powder form. By mixing six parts of this powder with 100 parts of water, the solution is prepared. The solution is then sprayed over the surface of timber. This treatment prevents attack from termites. The surface may be painted to get desired appearance.

Uses of Timber

 For heavy construction works like columns, trusses, piles

 For light construction works like doors, windows, flooring and roofing.

 For other permanent works like for railway sleepers, fencing poles, electric poles and gates.

 For temporary works in construction like scaffolding, centering, shoring and strutting, packing of materials.

 For decorative works like showcases and furnitures.

 For body works of buses, lorries, trains and boats

 For industrial uses like pulps (used in making papers), card boards, wall papers

For making sports goods and musical instruments.


Tuesday, March 21, 2017

What Is Cement - Sinhala

What Is Cement - Sinhala

සිමෙන්ති කියන්නෙ මොනාද?

ඇත්තටම සිමෙන්ති කියන්නෙ මොනාද? හැමෝටම ඒගැන අදහසක් ඇති. ඇත්තටම සිමෙන්ති කියන්නෙ Binding agent එකක්. ඒ කිව්වෙ වැලි, ගල්, ගඩොල්, වගේ දේවල් එකක් හෝ කිහිපයක් ශක්තිමත් ලෙස එකට බන්ධනය කල හැකි ද්‍රව්‍යක්.
සිමෙන්ති විවිධ වෙළඳ නාම වලින් වෙළඳපොළට එනව, ඉතින් එ් එක එකක් විවිධ වූ වැඩ සඳහා භාවිතා කරනව, 
පහළ තියෙන්නේ Tokyo Super යන වෙළඳ නාමයෙන් යුත් වෙළද පොළේ තිබෙන සම්මත බෑග් එකක්.
සාමාන්‍යයෙන් හොල්සිම් වගේ අමු හුණු ගල් මිශ්‍ර සිමෙන්ති කොන්ක්‍රිට් වහළවල් (Slab) වලට භාවිතා කරන් නෑ, හේතුව තමයි අමු හුණු ගල් මිශ්‍ර සිමෙන්ති දාල ස්ලැබ් එකක් හැඳුවම එ්ක අව්වට පැළෙන්න ගන්නවා. එ් නිසා තමයි ස්ලැබ් වලට Tokyo Super, Ultra Tech වගේ බෑන්ඩ් එකක් යොදාගන්නේ.

සිමෙන්ති නිෂ්පාදනය

විවිධ වර්ග වල සිමෙන්ති නිෂ්පාදනය කිරීමට විවිධ ක්‍රම තිබේ. සාමාන්‍යයෙන් ordinery portland cement (OPC) සිමෙන්ති නිෂ්පාදනය කරන්න අවශ්‍ය වෙන්නෙ හුණුගල් සහ මැටි. මේ දෙක හොදින් කවලම් කරල සෙල්සියස් අංශක 1400 විතර රත් කරයි. මේහිදී සිදු වන ප්‍රතික්‍රියා පහත පරිදි වේ.

1. හුනුගල් සෙල්සියස් අංශක 800 දි, කැල්සියම් ඔක්සයිඩ් සහ කාබන් ඩයොක්සයිඩ් හදනව.
හුනුගල් + සෙල්සියස් අංශක 800 = CaO + CO2

2. ඉහත සෑදුනු කැල්සියම් ඔක්සයිඩ්(CaO) මැටි වල ඇති අයන් ඔක්සයිඩ්(Fe2O3) සහ ඇලුමිනියම් ඔක්සයිඩ්(Al2O3) සමග ක්‍රියා කර 3CaO.Al2O3( C3A) හා 4CaO.Al2O3.Fe2O3(C4AF) සාදනව
CaO + මැටි + සෙල්සියස් අංශක 1000 = C3A + C4AF-----------------------------1

3. ඉහත සෑදුනු CaO මැටි වල සහ හුනුගල් වල ඇති සිලිකා සමග ක්‍රියාකර 3CaO.SiO2(C3S) හා 2CaO.SiO2(C2S) හදනව.
CaO + මැටි හා හුනුවල සිලිකා + සෙල්සියස් අංශක 1400 = C2S + C3S----------------2

ඉතින් 1 සහ 2 ට (C3A,C4AF,C2S ,C3S) තමා අපි සිමෙන්ති කියන්නෙ

දැන් මේ මිශ්‍රණයට ජිප්සම් දාන්නත් ඕනෙ. ජිප්සම් දැම්මෙ නැත්තම් අපිට මුකුත් කරන්න බෑ. සිමෙන්ති වලට වතුර දැම්ම ගමන් ගල් වෙලා ඉවරයි. ජිප්සම් දාන්නෙ setting time එක පරක්කු කරන්න. සිමෙන්ති හැදුව වගේ නෙමෙ ඒකෙන් අපිට ඕනෙ වැඩේ හරියට කරන්න යම්කිසි කාලයක් ඕනෙ. ඒ නිසා තමා ජිප්සම් දාන්නෙ. තව දෙයක් තමා ජිප්සම් දානකොට ගොඩාක් පරිස්සම් වෙන්න ඕනෙ. මොකද ජිප්සම් වල quality යේ පොඩි හරි වෙනසක් උනොත් ඒක සිමෙන්ති වලට ඉතාමත් විශාල බලපෑමක් කරනවා. 

සිමෙන්ති වර්ග

සිමෙන්ති වර්ග කිව්වම හිතන්න එපා මම අායේත් වෙලඳ නාම ගැන කියනව කියල. සාමාන්‍යයෙන් ලංකාවෙ තියෙන සෑම සිමෙන්ති බ්‍රෑන්ඩ්  SLS සහ BS සම්පූර්න කරනව. ඉතින් ඔය මොනා කිව්වත් ඔක්කොම එක වගේ හොදයි. ආයි කාරනාවට ආවොත්, සිමෙන්ති වර්ග ගොඩක් තියෙනව. ඒත් ප්‍රධාන වශයෙන්,

1. Rapid hardening portland cement
OPC තරම්ම වේගයකින් සෙට් වෙනව. ඒත් OPC වලට වඩා ශක්තියෙන් වැඩියි.

2. Low-heat portland cement
නමේම තේරුම තියෙනව. OPC වලට වඩා hydration process පිටවන තාපය අඩුයි. ලොකු ඉදිකිරීමක් කරනකොට පිටවන තාපය වැඩි උනොත් එම තාපය හේතු කොට ගෙන ඉදිකිරීමේ ඉරිතැලීම් ඇති වෙන්න පුලුවන්. එවැනි අවස්ථාවල තමා මේ සිමෙන්ති භාවිත වෙන්නෙ. විශේෂයෙන්ම විශාල වේලි, බිත්ති, කොන්ක්‍රීට් සැකිලි වල වගේ.

3. White portland cement
OPC වලට සමානයි. ඒත් සුදු පාටින් යුක්තයි. අලංකරනය තමා මෙහි අරමුන. සුදු පාට වෙන්න නිෂ්පාදනයේදී කෙයොලින් සහ චෝක් 

4. Hydrophobic portland cement
සිමෙන්ති අංශු ජලය නොගැටෙන පටලයකින් යුක්ත වෙනව. ආර්ද්‍රතාව වැඩි ප්‍රදේශ වල ගබඩා කරන්න වෙනකොට මේ සිමෙන්ති තමා ගන්නෙ

5. Sulphate resisting portland
OPC සිමෙන්ති වලට වඩා මේ සිමෙන්ති සල්ෆේට් වලට ප්‍රතිරෝධය දක්වනව. කොන්ක්‍රීට්, සල්ෆේට් සමග ගැටෙන අවස්තාවල(සල්ෆේට් විශාල වශයෙන් පවතින පස් සහ ජලය ඇති අවස්තාවල) භාවිත කරනවා

6. Super sulphated portland cement
OPC සිමෙන්ති වලට වඩා මේ සිමෙන්ති අම්ල වලට ප්‍රතිරෝධය දක්වනව. ආද්‍රතාව වැඩි ප්‍රදේශ වල ගබඩා කිරීමෙන් වලකින්න

7. High alumina cement
ශක්තිමත් බව ක්‍රමයෙන් වැඩි වෙනව. පලමු පැය 24 තුල ශක්තිමත් බවින් 75% ලබා ගන්නව. විශාල තාපයක් පිට කරනව. මුහුදු ජලය සදහා හොද ප්‍රතිරෝධයක් දක්වනවා. උෂ්න කලාප වල භාවිතයට සුදුසු නොවේ.

8. Portland blast furnance cement
OPC සිමෙන්ති වලට වඩා මේ සිමෙන්ත පිටකරන තාපය අවම වෙනව. ඒ වගේම අම්ල සදහා හොද ප්‍රතිරෝධයක් දක්වනවා

9. Quick setting cement
මිනිත්තු 5 පලමු සෙට් වීම ඇරබෙනව. මිනිත්තු 30 අවසාන සෙට් වීම ඇරබෙනව. OPC වලට වඩා ඉතාමත් වේගයෙන් සෙට් වෙනව.

10. ordinary portland cement(OPC)
මෙන්න අපි හැමෝම දන්න සිමෙන්ති. ලෝකෙ වැඩියෙන්ම භාවිත කරන්නෙ මේ සිමෙන්ති තමා. අනිත් විශේශ සිමෙන්ති වලට වඩා ලාභදායකයි. ඕනෑම ඉදිකීරීමක් සදහා යෝග්‍යයි.

බාල සිමෙන්ති හදුනා ගනිමු.

 සිමෙන්ති බෑග් එකේ මැස්ම හානි වෙලාද කියල බලන්න. එහෙම නම් ඒ වගේ සිමෙන්ති එ තරම් හොද නෑ

 සිමෙන්ති බෑග් එක ප්‍රවාහනයේදි හෝ බෑමේදි නැවිමක් සිදුවෙලාද කියල බලන්න.

සිමෙන්ති බෑගය සිරස්ව තබා හොදට තදට පැක් වෙලා තියෙනවද කියල බලන්න.

 සිමෙන්ති බෑග් ගබඩා කරන්න කලින් ඉරිලද කියල බලන්න. එහෙම ඉරිල නම් එවැනි බෑග් ගබඩා කරන්න එපා

සිමෙන්ති බෑග් එකක බර කිලෝ 50.25ක් තියෙන්වද කියල බලන්න. බර කිලෝ 50යි. ඉතිරි 0.25 බෑග් එකේ බර. එහෙම නැත්තම් සිමෙන්ති කොට්ට 4 ගත්තොත් ඔයාට කිලෝ 1 පාඩුයි.

ගබඩා කර තබන කාලයත් සමග සිමෙන්ති වල ශක්තිමත් භාවයේ විචලනය...

ගබඩා කර තබන කාලය(මාස)       ශක්තියේ අඩුවීම
3                                                20%
6                                                30%
12                                              40%
24                                              50%

ඉතින් පුලුවන් තරම් නිෂ්පාදන දිනයට ලග සිමෙන්ති මිලදී ගන්න උත්සහ කරන්න.

සිමෙන්ති ගබඩා කිරීම.

එලිමහනේ ගබඩා කිරීමේදී සැලකිලිමත් වියයුතු කරුණු...

 පොලවේ සිට අගල් 4 ක් පමන උස වියලි ස්ථනයක (ලෑල්ලක වගේ) ගබඩා කරන්න.
 සිමෙන්ති ගොඩ පොලිතින් කවර භාවිත කර සම්පූර්නයෙන් ආවරනය කරන්න.
 සිමෙන්ති ගොඩේ උඩ කොටස වහලයක හැඩේට සකසන්න. (වතුර රැදී නොතිබී ගලායන පරිදි)
 සුලගකදී පොලිතින් කවර ගැලවී නොයන පරිදි පොලිතින් කවර වල යට කොටසට බරක් එල්ලන්න.

ගබඩාවක ගබඩා කිරීමේදි සැලකිලිමත් විය යුතු කරුණු...

ගබඩාව වතුර නොයන පරිදි නිර්මාණය කර ඇත්දැයි බලන්න
 ගබඩාවේ ගබඩා කිරීමේදී මුලින්ම ගබඩා කල සිමෙන්ති මුලින්ම එලියට ගත හැකි පරිදි අසුරන්න.
 බිත්ති සහ සිමෙන්ති කොට්ට අතර අඩි 2 ක පරතරයක් තබන්න.
 එක උඩ එක සිමෙන්ති කොට්ට තැබීමේදි 10 ට වඩා අඩුවෙන් තබන්න.
 සිමෙන්ති කොට්ට පොලිතින් භාවිතයෙන් වසා තබන්න.
 පොලවේ සිට අගල් 4 ක් පමන උස වියලි ස්ථනයක ගබඩා කරන්න.

What Is Cement - Sinhala