Tag: building material stone

Building Material – Stone ! Testing of Stones !

When stones are proposed to be used in very big and costly structures, some of very important properties need to be tested strictly in accordance with the procedures laid down by the authorized institutions like Indian standards (BIS) .

Selection of Samples :

The sample shall be selected from the quarried stone or taken from the natural rock & shall be of adequate size to permit the separation of the requisite number of test pieces.

Following tests performed to find suitability of a stone for its use in any engineer works :

1) COMPRESSIVE STRENGTH TEST :

Samples : Cubes of 5cm side or cylinders of 5 diameter and of same height. The top and bottom surfaces shall be made as possible by polishing.

Procedure : The tests shall be carried out on dry as well on as on saturated sample.

For saturating, the samples of proper dimensions shall be immersed in water at 20c -30c for 72 hours and then tested after removing all moisture by rubbing with dry cloth.

For dry samples, samples of proper shape and size shall be placed in an oven at 105c for 24 hours and then cooled in a desiccators (and not in open air ) to room temperature.

Loading :  Each sample shall be loaded individually by placing it over the loading plate of a UTM (Universal testing machine). The load will be increased very gradually, at a rate of 140kg/cm2 per minute or as prescribed in the code. This process (of loading) is continued till the sample bricks, i.e. when first crack appears in it and the sample stops taking any further load.

Calculations : Compressive strength, co, shall be calculated by using relationship:

                                                         Co = p/a

  p = load at failure point ; a = cross sectional area of the sample

The result of each sample is expressed in kg/cm2. Six sampls should be tested from each type of rock and the average value is taken as compressive strength.

2) TRANSVERSE STRENGTH TEST :

Sample : A bar of 20 cm length, 5 cm thickness, and 5 cm width which must be properly dried and smoothened by polishing.

Procedure : Five to six such samples are prepared from the representative rock specimens and tested individually. The sample is placed on two horizontal supports given at the ends leaving a clear distance of 15 cm between the two supports. It is then loaded transversely and the load is applied gradually.

Calculations : The load “w” at which the sample starts breaking is noted and used to calculate modulus of rupture of the stone using following relationship:

                                                                   R = 3wl/bd2

w = load at failure; l = length of the sample ; be = width of the sample and d = thickness of the sample.

3) WATER ABSORPTION : (refs. Is – 1125- 1974)

Sample : Take about 1 kg samples from representative stones that have been crushed and made to pass through is 20 mm sieve

Procedure : The selected and weighed sample is placed in distilled water in a glass vessel at room temperature (20 degree C-30 degree C ) for a period of 24 hours.

The sample is then taken out, piece-by-piece, surface dried with a damp cloth and the air-dried by spreading over a damp cloth for ten minutes. The sample is then weighed, ;let this weight be W1

The sample is then dried in an oven at 105 degree C at 105 degree C +10 degree C for at least 24 hours and then cooled by placing in a desiccators. It is weighed again let this weight be w2.

Calculations : Water absorption, or absorption value is calculated by the relationship:

                                                                               (W1-W2)/ W2 x 100

4) WEATHERING RESISTANCE (is ref.1125-1974) :

This test determines the resistance of stones to deterioration due to exposure to cold humid temperatures favourable for formation of ice and salt crystals within their pores.

Samples : Cubes of 5 cm sides or cylinders of 5 cm diameter prepared from representative rocks and given a fine polish at the ends are used as test samples.p

Procedure :

(i) Take three samples, previously dried in an oven at 105 degree c + 5 degree c for 24 hours and cooled to room temperature in a desiccators. The sides of the samples are smooth finished. The so dried samples shall be weighed. Let their dry weight be W1.

(ii) Each test samples shall be freely suspended in water for 24 hours at 20 degree c-30 degree c and then weighed in that condition. Let this weight be W2.

(iii) The test sample shall be taken out of water and surface dried and weighed in air; let this weight be W3.

(iv) Each sample is placed separately in a dish made of porcelain or glass containing a solution of 2 gm powdered gypsum in 25 ml of water .

(v) These three dishes so prepared with the test samples are placed in a ventilated oven at 105 degree c+ 2 degree c for 5 hours (or till the evaporation of water of solution).

(vi) The dishes containing the samples are now removed from the ovens. They are allowed to cool naturally to room temperature. This process completes one cycle of treatment prescribed under the test.

(vii) Each sample is placed in a fresh dish in a new solution of 2 gm of gypsum in 25 ml of water and the same process of placing in ventilated oven is repeated.

Thirty such cycles are repeated on all the three samples.

(viii) Each sample is first cleaned by a stiff brush to remove superfluously sticking gypsum and then immersed in clean water for 24 hours.

(ix) Each sample is taken out from water, surface dried and weighed fourth time and fifth time.

Fourth time in air (W4)

And fifth time (W5) in a suspended state in water

Calculations: as a result of 30 cycles of drying in presence of gypsum solutions, each sample is likely to undergo some changes in its absorption and in its volume. The greater the changes, the lower is their resistance to weathering or, in other words, higher is the weathering of stones.

The absorption values are given as described :

Original Absorption (A1) = ( W3 -W1 ) / W1 x 100

Final Absorption ( A2) = ( W4 – W1) / W1 x 100

The volumes of the test specimens :

Original Volume V1 = (W3 – W2) / D

After 24 hours immersion

Final Volume after 30 cycles ( V2) = (W4 – W5) / D

(d = density of water at the time of recording)

5) DURABILITY OF STONE :

This is almost like test 4 except that in this Case the solution used is that of sodium sulphate  decahydrate.

Samples : Take 3 cubes of 5 cm sides or cylinders of 5cm dia. From the representative rocks. These shall be dried by placing in an oven for 24 hours at 110 degree c + 10 degree c.

Test procedure :

  • The dried test specimens are first weighed in dry condition. Let this weight be w1.
  • They are then suspended in a saturated solution of sodium sulphate decahydrate  at room temperature for duration of 18 hours.
  • They are then taken out of the solution, air dried for half an hour and then dried in an oven at 105c+5c for 4 hours.
  • The samples are then cooled to room temperature. This completes one cycle of the test.
  • The above process (ii-v) is repeated on the samples as selected at (i) for 30 cycles.
  • After thirty cycles, each sample is thoroughly washed to remove any sticking sodium sulphate . it is then weighed finally let this weight be W2.

This may be in any case less than W1 the lose in weight calculated in percentage terms as follows is a qualitative measure of durability of the stone.

Calculation :

(W1 – W2 ) / W1 x 100

Greater the loss in weight, poorer is durability.

Building Material – Stone ! Characteristics of Stone – Part 3

1.) Appearance :

The Stone which are to used for face work should be decent appearance. These should be capable of preserving their colour uniformly for a long time.

The Stone should have a uniform & pleasing colour & free from cavities,cracks,flaws & patches of loose & soft materials.

2.) Strength :

Stone has sufficient crushing strength to withstand the load of superstructure.Generally n’t less than 1000 kg/cm2.

3.) Hardness ,Toughness & Resistance to abrasion :

Stone are used for staircase , pavements, road metal or railway ballast should be sufficient hard,tough & resistance to abrasion.

4. ) Durability :

It is durable enough to resist the effect of weathering agencies. They should have fine grained , compact & crystalline structure.

5.) Texture :

Stone has suchg texture are strong & durable.

6.) Work ability :

Stones to be used for ornamental carving and architectural work , should be easily & economically dressed.

7. ) Seasoning :

Stone is used for interior work also so it should be proper seasoned because the presence of moisture makes stone soft & liable to an early decay when used in structural work.

8.) Porosity :

Stone should have less porosity. It should not absorb water more than 5% of its own weight when kept immersed for 24 hours.

9.) Resistance to Fire :

Stone should be able to resist high temperature. Its mineral constituents should have equal coefficient of expansion.

10.) Specify Gravity :

Stone to be used on heavy engineering works,docks,gravity,dam etc. should have high specify gravity.

11.) Resistance to Electricity :

Stone should be Non -absorbent like marble & slate so that they can offer good resistance to electricity.

Building Material – Stone ! Classification of Stone/ Rock

Stone/Rocks are classified in the following three ways :

1) Geological Classification

2) Physical Classification

3) Chemical Classification

A) Geological Classification : Based of formation of Rocks & further classified three types :

i) Igneous Rock

ii) Sedimentary Rocks

iii) Metamorphic Rocks

i) Igneous Rocks :

The rocks formed directly by solidification of molten material , either on surface or the surface of earth called Igneous Rocks.

Ex : Granite, Basalt, Trap & Delorite.

Formation of Igneous Rocks :

At a certain depth , the temperature of material with in the earth’s crust become so high that the existing material may acquire a molten state is called Magma.

When the molten material out from earth called Lava. When the molten condition change due to temperature, pressure & chemical composition ) surrounding the magma, it changes into a solid state in the form of simple solid masses known as Igneous Rocks.

These rockes divided further three classes :

  1. Plutonic Rocks
  2. Hypabyssal Rocks
  3. Volcanic Rocks
  1. Plutonic Rocks : formed due to cooling of magma at a considerable depth from earth surface. The cooling is slow & the rock posses coarsely grained crystalline structure. Ex Granite.
  2. Hypabyssal Rocks : these rocks are formed due to cooling of magma at a relatively shallow depth (2-3 KM) from the earth surface. The cooling is quick & possess finely grained crystalline structure. Ex. Delorite
  3. Volcanic Rocks : Formed due to pouring of magma at a earth surface. The cooling is very rapid. Hence these rocks are extremely fine grains in structure.

They frequently contain some quantity of glass which is a non crystalline material. Ex. Basalt.

ii) Sedimentary Rocks / Stratified & Aqueous Rock  :

these formed by consolidation/break of particles of the pre- existing rocks, under the effect of weather agencies (ice,water, air, sun heat , gases etc) are called sedimentary rocks.

These are most widespread rocks found covering a great part of earth.

Ex. : Gravel, sandstone, lime stone, lignite etc.

Formation :

  1. Disintegration of pre-existing rocks under the effect of weather agencies.
  2. Transported by these natural agencies to river beds , lake basin, seas & ocean or in suspension to other place.
  3. Setting down the suspended particles or precipitation of the soluble constituents.
  4. Compaction and consolidation of the deposited sediments either due to pressure or chemical action like silica, lime ,iron etc.

Sedimentary following four types of deposit occurs :

A) Residual Deposits

B) Sedimentary Deposits

C) Chemical Deposits

D) Organic Deposits

Residual Deposit : Some portion of product of weathering remain at the site of origin known as Residual Deposits.

Sedimentary Deposits : The soluble products of weathering are carried away in suspension and when such products are deposited, they give rise to the sedimentary deposits.

Chemical Deposits : Some material carried away in solution may be deposited by some phsio – chemical processes such as evaporation , precipitation etc.

Organic Deposits : Some portion of the product of the weathering gets deposited through the agency or organisms.

iii) Metamorphic Rocks :

The rocks formed from the pre- existing rocks with in the earth crust, under the influence of variation in temperature or pressure are called Metamorphic Rocks.

Ex : Marble  , Slate & Gneiss etc.

Formation :

The pre- existing rocks within the earth crust don’t change their state so long as their temperature& pressure remain unchanged known as Metamorphic rocks.

  1. Marble : Lime Stone
  2. Slate : Shale
  3. Quartzite : Sand Stone
  4. Gnesis : Granite

Following four types metamorphic occur with various combinations of heat , uniform pressure & directly pressure :

A.) Thermal Metamorphism – The heat is the pre-dominant factor.

B.) Cataclastic Metamorphism – At the surface of earth, the temperature are low & metamorphism is brought about by directed pressure only.

C.) Dynamo – Thermal Metamorphism – There is a rise in temperature with increase in depth. The heat in combination with stress, bring about the changes in rock.

D.) Plutonic Metamorphism : The stress is effective only upto a certain depth. This is due to the fact that rocks become plastic in nature at certain depths. The metamorphic changes at great depths are therefore brought about by uniform pressure & heat.

2) Physical Classification : Based on physical properties.

Further classified into three types :

  1. Un-Stratified Rocks :The rocks which don’t show distinct signs of layers and cannot be easily splited up into the layers are called Unstratified rocks. The structure may be crystalline granular ex : Granite, Basalt & traps etc
  2. Stratified Rocks : The rocks which show distinct signs of layers and can be easily splited up into layers are called Un-Stratified Rocks. Ex : Sand Stone , Lime Stone etc
  3. Foliated Rocks : The rocks which can be splited- up into thin sheets or in a definite direction known as as foliated rocks.

Ex : Slate , Schist etc.

3.) Chemical Classification :

Further classified into three types :

1.) Siliceous Rocks : The rocks having silica (SiCO2) or sand as their major constituent are called Siliceous Rocks.

These rocks are hard & durable. They aren’t easily affected by the weather agencies. Ex: Granite , Sandstone , Quartzite etc.

2.) Argillaceous Rocks : The rocks having Alumina (Al2O3) or clay as their major constituent are known as argillaceous rocks. These rocks may be dense and compact or may be soft like mud stone etc.

3. ) Calcareous Rock : These rocks having calcium carbonate (CaCo3) or lime as their major constituent are called calcareous rocks. The durability of these rocks will depend upon the constituents present in the surrounding atmosphere. Ex : Lime Stone, Marble & Kankar etc.

Building Material – Stone & Uses of Stone – part 1

Building Stone :

A natural material of construction obtained from rocks by any suitable method is call Stone & which is used for construction of structure called Building Stone. Stones are naturally occurring (compact, solid & massive ) building material.  

Building Stone are obtained from a quarry by disintegration of Rocks. The Good Stone are not easily & cheaply available everywhere/ every state & are difficult to handle because of heavy in weight.

Uses :

 Now a  days , brick in cement mortar & cement concrete are replacing stone as a building material.

  1. Construction of heavy & permanent engineer structure such as dam, docks, harbours, light houses, abutments & pier of bridges etc.
  2. Their uses for building work in hilly areas, where a good quality of stone is easily & cheaply available.
  3. Stones used as an aggregates for concrete.
  4. Slabs for paving floors.
  5. Flags for paving streets.
  6. Ballast in railway tracks.
  7. Road Metal
  8. The pyramids of Egypt , The Temple of Jagannathpuri, The Taj Mahal ,The Red Fort ,The great China Wall etc.  hundred of historical building are made of stones.