Stone in Civil Engineering

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Building Stones

Stones used in most historical places

Pyramids of Egypt

Taj Mahal of Agra,India

Great wall of China

Greek and Roman structures

Quaid’s Mausoleum in Karachi

Shahi mosque in Lahore

Forts at Rohtas, LahoreGrand Trunk Road

Lloyd’s Barrage at Sukkur

Stone as building material

lost its importance due to Advent of cement and steel.

Transportation difficulties

Dressing problems

Stone: A construction material derived from rocks in the earth’s crust and mixture of two or more minerals.Mineral is a substance which is formed by the natural inorganic process and possesses a definite chemical composition and molecular structure

.Civil Engineering Uses

Construction of dams, weirs, harbors, bridge abutments, etc Face work of structures for appearance and ornamental value Road metal and railway ballast Aggregate for concrete Stone dust as substitute for sand Thin slabs for roofing, flooring and pavements Limestone for manufacture of lime, cement, etc

Classification of Rocks

Geological classification

Igneous rocks (primary, un-stratified, eruptive) – cooled down molten volcanic lava (magma). Basalts and granites.

Sedimentary rocks (aqueous, stratified) – gradually deposited disintegrated rocks. Sand stones and lime stones\

Metamorphic rocks – transformed due to great heat and pressure. Granite to gneiss, lime stone to marble, shale to slate

Physical classification Stratified rocks – separable distinct layers. Cleavage plane of split visible. Slate, sandstone, lime stone Un-stratified rocks – no sign of strata, cannot be easily split into slabs. Granite, basalt, trap Foliated rocks – having tendency to split up only in a definite direction Chemical

Classification of Siliceous rocks – containing silica SiO2 (sand) and silicates. Granite, basalt, trap, quartzite, gneiss, syenite, etc

Argillaceous rocks – containing clay or alumina Al2O3. Slate, laterite, etcCalcareous rocks – containing calcium carbonate or lime. Limestone, marble, dolomite, etc

Practical Classification

Granites Basalts Marbles Sandstones Slates, etc

Characteristics of Good Building Stones

Appearance & color – uniform color, lighter shades preferred.Structure – Not dull in appearance, crystalline homogenous close Hardness– resistance to abrasion, friction and wear. Hardness scale 1 to 10 Toughness – Withstand impact, vibrations, moving loads Dressing – uniform texture and softness for fine surface finish Porosity and Absorption – exposed surface absorbs rain water forming acids causing crumbling action. Cyclic freezing and thawing of pore water Seasoning – hardening and weathering affect due to evaporation of quarry sap and formation of months for proper seasoning Weathering – resistance to action of weather Resistance to fire – free from calcium carbonate or oxides of iron Durability – compact, homogenous and less absorptive is more durable

Moh’s Hardness Scale

1 Talc, scratched easily by thumb nail

2 Gypsum, scratched by thumb nail

3 Calcite, scratched not by thumb nail but by knife

4 Fluorite, cut by knife with difficulty

5 Apatite, cut by knife with difficulty more than 4

6 Orthoclase, cut by knife with great difficulty

7 Quartz, not scratched by steel, scratches glass

8 Topaz

9 Sapphire

10 Diamond

Tests of Stones

Weathering test of natural building stones

Durability test of natural building stones

Water absorption and porosity test

Compressive strength test

Selection of Sample for Tests  A truly representative sample of grade of stone should be selected Sample may be selected from quarried stone or natural rock Separate samples weighing at least 25 kg each shall be collected from differing strata Test pieces for toughness or compressive strength test shall be at least 10.0 x 12.5 x 7.5 cm in size Test pieces shall be free from seams or fractures In case of field stones and boulders separate samples shall be selected of all classes of stones based on visual inspection

Weathering Test

Specimen 5 cm diameter, 5 cm high cylinders 5 cm cubes Smooth finished, edges rounded to 0.3 cm Three test specimens oven dried at 105 ± 5°C for 24 hrs and cooled in desiccators down to room temp 20 to 30°C

W1 weight of cooled and dried test piece, weighed to nearest 0.01 gm Specimens submerged in water for 24 hrs at room temp

W2 immersed and freely suspended sample weight Remove the specimen from water, wipe off surface water

W3 weight after removal from water Place the specimen in a glass dish in solution of 25 ml of water and 2 gm of powdered gypsumSpecimen dish kept in oven at 105 ± 5°C for 5 hrs till gypsum powder becomes dry Specimen cooled down to room temp 25 ± 5°C Heating and cooling cycle is repeated 30 times Specimen removed and cleaned with wire brushSpecimen kept immersed in water for 24 hrs.

W5  weight of sample freely suspended, immersed in water

A1: Original absorption of specimen on 24 hr immersion in water

A2: Final absorption after 30 cycles

V1: Original volume after 24 hrs immersion in water

V2: final volume after 30 cycles. density of water at observation temperature Durability Test Specimen 5 cm diameter, 5 cm high cylinders or 5 cm cubes Smooth finished, edges rounded to 0.3 cm At least three test samples dried for 24 hrs and weighed as W1 Samples suspended in solution of 14% sodium sulphate decahydrate (density 1.055 kg/m3) for 18 hrs at room temperature Samples air dried for 30 minutes Samples now oven dried for 24 hrs at 105 ± 5°C Samples cooled down to room temperature to complete one cycle Weight W2 at the end of every 5th cycle noted and 30 cycles completed

Durability expressed as Water Absorption and Porosity

Change in weight =(W1-W2/W1)x100

Test Sample preparation Sufficient material is crushed Material passing 20 mm sieve is retained Material washed to remove dust About 1 kg material is immersed and soaked in distilled water at room temperature for 24 hrs Entrapped air is removed by vigorous rotational motion Sample taken out of water and spread on cloth exposed to atmosphere in shade for ten minutes

Water Absorbtion and Prosity Test 

Dry the Surface of test pieces dried with cloth On drying of surface, sample weight  W1 recorded Distilled water added to sample in a graduated glass cylinder in portions of 100 ml till level of water reaches 1000 ml mark Entrapped air is removed after each addition of water Total quantity of added water is recorded as W2 Sample taken out of cylinder and dried in desiccators at 100°C for 24 hrs W3 recorded when sample is cooled down W1: Initial weight of dried sample W2: Weight of water consumed in saturation W3: Final weight of sample after drying for 24 hrs .

True Specific Gravity Tes

Crush 0.5 kg of thoroughly washed specimen to 3 mm size, mix and make samples of 50 gm each Sample ground in agate mortar to pass 150 microns sieve Sample is dried at 100°C, cooled in desiccators Specific gravity bottle is cleaned, washed, dried, cooled and weighed (W1)About 15 gms sample placed in specific gravity bottle closed with stopper and whole weighed as W2 Three fourths of specific gravity bottle filled with distilled water Bottle boiled for 10 minutes while removing entrapped air Bottle cooled to room temperature, filled with water, stoppered and weighed as W3 Bottle emptied, washed, filled with only as W4

Test for Compressive Strength

Specimen Preparation Load bearing surfaces finished as nearly true, parallel and perpendicular planes as possible Loaded face dimensions measured to nearest 0.2 mm Specimens kept immersed in water at 20 to 30°C for 24 hrs for saturated condition testing Specimens oven dried at 105 ± 5°C for 24 hrs and cooled down to room temp for dry testing .Testing load gradually increased @ 140 kg/cm2 per minute until break down Max load applied divided by area of bearing surface is taken as the compressive strength of specimen Quarrying and Dressing

Quarrying: An art of extracting from the rock beds stones of different varieties used for general building work and broken stones for roads and concrete work, etc Quarry: The place from stone is obtained by digging or blasting etc

Digging or Excavating Method. Stones occurring as detached nodules may be dug using manual methods like crowbars etc

Heating Method. Rock surface is heated for several hours resulting into unequal expansion and crushing of rock into small pieces

Wedging Method. Layered rock is split at cleavage or seam using steel wedges and pins Blasting Method. Hard and compact rock is  blasted out using explosives techniques comprising boring, charging, tamping and firing

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i am a student of civil engineering takes much interest in this field

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