Strength of Materials DOC

Adarsh Institute of Technology & Research Centre, Vita

STRENGTH OF MATERIALSLaboratory Journal

SE Part III According to the Syllabus of Shivaji University, Kolhapur Effective From Jully 2008

Department of civilAdarsh Institute of Technology & Research Centre, Vita EXPERIMENT NO. 1 STUDY OF UNIVERSAL TESTING MACHINE TITLE:- Study of Universal Testing Machine. THEORY:- The behavior of various materials is the study with the help of this machine. This machine does test like tensile, compression, bearing, shearing etc.The UTM contain two main partsi) Control panelii) Loading panelLoading panel:-This panel contains main three parts.a) Upper cross headb) Middle cross headc) Lower cross headUpper cross head: - It is connected between two plane bars. It has two jaws with jaw handle .For upper cross head remains constant for tension test.Middle cross head: - It is connected between two screwed bar. It has also a jaw with jaw handle similar to upper cross head. It moves upward for tension test and downward for compression, shear, hardness and bending test.Lower cross head: - It is situated on hydraulic ram. Loading panel is connected to control panel with the help of oil pipes .Tension test is done between upper and middle cross head compression, shear, hardness and bending test are taken in between middle and lower cross head.Control Panel: - It has maximum capacity 60 ton. Circular dial is main part of the panel. This dial show reading from 6-60 tone. It has two pointer, reading and dummy pointer. These pointers are adjustable. This panel also contains release and loading value. When specimen is fail during any test then loading valve is closed and up slowly. Releasing valve move up and down and loading valve is on or off as per requirement graph is drawn in between two panels.

EXPERIMENT NO. 1 (B)TENSILE TEST ON METALSOBJECTIVE: - Tensile test on mild steel specimen.PURPOSE AND DISCUSSION:- Purpose: - purpose of the test is to know the elastic properties, tensile strength and the ductility of steel. From this test we obtain. i) Stress strain relationship of steel ii) Modulus of elasticity.iii) Yield strength.iv) Ultimate tensile strength. v) Percentage elongation of steel at failure under tensile load. DISCUSSION:- BEHAVIOUR OF STEEL UNDER STRESS:- Steel is an important material used in structure as well as machines. While designing a steel member the designer should have an idea of properties mentioned above. The knowledge of behavior of steel under stress is very essential upto a certain stress limit the steel behaves as an elastic material but beyond that the steel behaves differently. The designer should have an idea of youngs modulus of elasticity, the elastic limit and the maximum tensile strength. Also the percentage elongation at failure is a measure of ductility of steel. We get all this information from one single test i.e. Tensile test on steel , (or for the matter on other metals also) in which specimen is subjected to tensile load gradually till it fails. DEFINITIONS:-a) Stress strain diagram: - The relation between stress and strain in a tensile test, drawn graphically with stress along x- axis, is called as stress strain diagramb) Elasticity: - it is property of material due to which a loaded material returns to its initial shape after the load is removed. c) Proportional limit and elastic limit: - the limit of stress up to which the stress is proportional to strain is called a limit of proportionality. The stress limit up to which if load is removed the deformation disappears is called elastic limit. Both these limits are so closed that for all practical purposes limit of proportionality and limit of elasticity are considered as same. Then, Then percentage reduction in area d = BEHAVIOUR OF VARIOUS MATERIALS: a) Mild steel has got definite yield point. It contains carbon content less than 0.3%. Medium carbon steel contains carbon 0.3% to 0.8%. High carbon steel contains carbon 0.8% to 1.5%. As the carbon content increases the strength also increases, but the ductility is reduced. High carbon steel does not show clear yield point. b) Cast iron is brittle, it does not exhibit any yield point, and it has a low limit of proportionality Its ductility is low. c) Non ferrous metals and their alloys:- These also do not show a definite yield point and their limit of proportionality is low. But they are ductile.APPARATUS AND MATERIALS:- APPARATUS:-i) Tensile testing machine or universal testing machine. ii) Extensometer.iii) Vernier calipers.iv) Scales.MATERIALS:- Mild steel specimens of circular cross section with gauge length equal to five times bar diameter (do). The specimen should extend beyond gauge length with a parallel length equal to 5.5 to 7 time diameter and then further sufficient length for graph at each end. The test piece should have preferable larger cross section at the end to ensure that the piece does not fail at ends. Transition curves with radius equal to do should be provided from the middle portion to the thickened ends. The gauge length should be marked by fine scribed lines. Incised marking should not been done

PROCEDURE:- i) Measure the diameter (do) of the bar accurately in mm at 3 places and find the mean value correct up to 2 places of decimals. Also measure the gauge length accurately (L0).ii) Fix the specimen in the grip holders of the tensile testing machine firmly in such a way that the load is applied as axially as possible. iii) Attach an extensometer firmly so as to measure the elongation during the loading between the gauge marks. iv) Bearing the load indicating pointer of the dial to zero and apply load slowly at the rate of about 1 kg/mm2/sec. the loading rate should be as uniform possible and any change should be as uniform as possible and any change should be made gradually without any shocks.v) Note down the reading of load and elongation at regular intervals of 100kg. load.vi) Also observe at what load the machine shows sudden increase in the deformation. This occurs when yielding take place.vii) Beyond the yield point the extensometer may be removed and the reading of elongation taken on scale. The rate of loading may be increased to about 3N/mm2/sec. as the stress starts increasing after plastic stage.viii) Note down the maximum load, the breaking load and the corresponding elongation.ix) Remove the fractured pieces of the specimen, place them together touching at the fracture and measure the length (Li) between the gauge marks. Also measure the diameter of the specimen at the fracture (di). x) Calculate stress and strain and plot the stress and strain diagram. xi) Calculate stress at yield point, maximum stress, breaking stress, percentage elongation and percentage reduction in area. Also calculate the modulus of elasticity from the straight line portion of the graph.

OBSERVATIONS AND CALCULATIONS:-OBSERVATIONS:- i) Original diameter of the specimen = do = ii) Original gauge length= L0 =5d0 =iii) Area of original cross section =A0= iv) Load at yield point = v) Maximum load = vi) Breaking load = vii) Final length between gauge marks = L1 =viii) Diameter of section after failure =d1= ix) Area of cross section at failure = A1= OBSERVATION TABLE:- SR.NO.LOADP(N)ELONGATIONe(mm.)STRESS=

STRAIN=Remarks Yield Point, Maximum load Break point.

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

CALCULATIONS:-i) Calculate stress and strain in column 4 and 5 of the observation table. ii) Stress at yield point = iii) Tensile strength = iv) Breaking strength =v) Percentage elongation = [(L1-L0) /L0]100vi) Modulus of elasticity = RESULTS:- 1) Yield point = 2) Tensile strength = 3) Breaking strength=4) Percentage Elongation =5) Modulus of elasticity=REQUIREMENTS:- Mild steel should have following properties.1) Yield point = 2) Tensile strength = 3) Percentage Elongation =4) Modulus of elasticity=CONCLUSION:-

EXPERIMENT NO. -2TITLE: - To determine the absorption of water of burnt clay building bricks. PURPOSE: - The purpose of the test is get an idea of quality of bricks using the methods of water absorption of bricks immersed in water for a specified period or by boiling them in water. ABSORPTION OF WATER:- (1) Bricks have pores in them. Due to this porosity the dry bricks when come in to contact with the water, absorb water through these pores. Larger the porosity more the absorption. Poorer the quality of bricks greater in the absorption of water and vice versa. The absorption is found out as weight of water absorbed as percentage of weight of dry bricks. (2) Bricks which are under burnt or which contain much of calcium carbonate or are made of such soil that they become porous and brittle have high absorption of moisture. Well burnt bricks, which are hard and dense with good ringing sound are less porous and absorb less water and so are preferred, for contraction.SIGNIFICANCE:- 1) The bricks should be as impervious to water as possible. But bricks being porous do absorb water. The bricks which absorb comparatively more water have comparatively lower compressive strength, resulting in lower strengths of walls.2) Also as the bricks absorb water from rain etc. create dampness inside the building resulting in unhealthy environment inside. 3) Bricks which absorb more water from cement mortal during construction of walls. Reducing the water content in the mortar which is vital for hydration and setting and thus reduce the strength of mortar and so of walls. 4) It is therefore necessary to use bricks which absorb as less water as possible. The absorption of water by bricks by weight varies from 5% to 25%. For good work the absorption should be less than 15% and in no case should exceed 20%. Also bricks should be wetted to saturation before using in walls and brick walls should be kept well watered, for curing , so as to avoid absorbing of water from mortar.

METHODS OF TEST:- There are two methods of finding out absorption of water by bricks. 1) 24 hours immersion cold water test. 2) 5 hours boiling water test. Sampling and sample size:- For testing for water absorption select 5 brick specimen at random and truly representative of the lot of 35,000 bricks and 15 nos. for a lot of 50,000 bricks. APPARATUS AND MATERIALS:- APPARATUS:- 1) A weighing balance correct up to 0.1 gm.2) A ventilated oven.3) Container for water in which bricks can be immersed, with arrangement for heating the water to boiling.

MATERIALS:- 1) Cold water test:- i) Dry the brick specimens in a ventilated oven at a temperature of 1050C to 1100C till the same attain substantially constant weight. ii) Cool the specimens at room temperature and weigh each specimen separately(w1) iii) Immerse completely the dried specimens in clean water at a temperature of 250Cto 290C for 24 hours. iv) Remove the specimens after 24 hours. Wipe out any traces of water with damp cloth and weigh each specimen separately (w2) the weighing should be completed in 3 minutes after removal from water v) Calculate the percentage of water absorbed by the bricks equal to = 100

OBSERVATION AND CALCULATION:-

Bricks identificationWeight of brick when dry(w1)Weight of saturated brick (w2) Percentage of water absorbed Pn =100Average water absorption.

B1

B2

B3

P =Average of result = =

P1 = 100 ; P2 = 100 ; P3 = 100

RESULT:- The absorption of water as percent by weight of given burnt clay brick is _____%

CONCLUSION:-

EXPERIMENT NO. 03TITLE:- Shear testing on mild steel.AIM :- To determine the shear strength of steel in i) Single shear ii) Double shear. PURPOSE:- The purpose of the test is to find out the shear strength of steel specimen subjected to single shear as well as to double shear. This test is useful in the design of riveted joints, as the rivets may be either in single shear or may be in double shear.Shear stress:- It is produced in a body when it is subjected to two equal and opposite forces spaced at an infinite decimal distance or tangentially across the resisting section. Shear stress, fs = = In case of a rivet the rivet has a circular cross section. A= d , fs = in single shear,Test:- Actually shear test is not yet standardized. I.S. has not specified any test. Reason IS that it is difficult to produce conditions of pure shear as some bending effect is likely to occur due to shearing load resulting in equal and opposite forces at a small finite distance. However a proper shear attachment as shown in the sketch can be used fairly satisfactorily. In this arrangement an upper anvil thus creating two shearing planes between their adjoining stresses. Specimen can be inserted to be sheared along either one section or two sections , by loading the upper anvil, keeping the whole assembly in a universal testing. APPARATUS:- i) Universal testing machine.ii) Shearing attachment with cutters.MATERIAL:- A round bar of 16mm dia. of mild steel of sufficient length for single and double shear testing.PROCEDURE:- i) Measure the diameter of the specimen.ii) Place the specimen in the cutter of shear attachment in such a way that only one section of the bar is subjected to shear.iii) Place the shear attachment in the universal testing machine. Apply a load and increase it gradually till the specimen fails. Note down the maximum load at failure .iv) For testing the specimen in the double shear insert the specimen so that it extends on both sides of the upper anvil and rests on both sides on the lower anvil. Apply and increase the load gradually till the specimen fails, by shearing off on both sides. Note down the maximum load at failure.OBSERVATIONS:-Sr.No.MaterialDia.(d)Area(A)Load P1 (kg)Stress (kg/mm)Load P2 (kg)Stress (kg/mm)Remark

1

Mild steel

RESULTS:-

EXPERIMENT No:- 04TITLE:- Compression test on timber. AIM:- To find compression strength of timber.1) Load applied parallel to grain 2) Load applied across to grainAPPARATUS :- 1) Universal testing machine. 2) Timber pieces.PROCEDURE:- 1) Measure the dimension of timber or wooden block. 2) Place wooden block in compression jaws.3) Apply load and increase it gradually till the specimen fails. Note down the maximum load reading. 4) This above process carry for two blocks first is grain is parallel and other for grain is across.5) Testing the compression on the two blocks and written reading of failure of specimen.6) Then remove the specimen from machine and seen the breaking structure of specimen.OBSERVATION TABLE:- Sr. No.Specimen SizemmmmmmLoad appliedLoad at failure(N)Remark

1

2

CALCULATIONS:- Compression strength =

RESULT:- 1) Load applied perpendicular to grain =2) Load applied across the grain =

EXPERIMENT NO:- 05TITLE: - Hardness test on metals. AIM: - To conduct the following hardness tests on metals.1) Brinell hardness test.2) Rockwell hardness test.PURPOSE AND DISCUSSION:-PURPOSE:- The purpose of the test is to know the effect of heat treatment such as hardening temperature, tempering etc and to check the quality and uniformity of products . To resist the wearing away of the material certain material is required in materials used for the rollers, tooth gear, slide ways, tool steels, Die steels etc. So materials for such uses is given heat treatment for hardening .The test can given us the idea of hardness of the metals. HARDNESS:- Hardness is defined as the resistance to local penetration or scratching or abrasion. It indicates the ability of the material to withstand the deformation under a locally applied load. Various tests have been developed to test resistance to either indentation (i.e. local penetration) or abrasion or scratching. But the indention test is the most widely used test. It is quick test and also a non destructive test. METHODS OF INDENTION TESTS:- The various methods of hardness tests are a) Brinell hardness test b) Rockwell hardness test c) Vickerss hardness testd) Dynamic indentation teste) Rebound test etc. Out of these tests the first three tests are very common the tests, mainly a) The Brinell hardness test b) the Rockwell hardness tests will be explained here. Brinell hardness test:- In this test a hard steel ball is forced into the surface of the test specimen, under standard conditions and the hardness is calculated by dividing the load by the curved surface area of the indention caused. Rockwell hardness tests :- In this test a diamond conical point or a hard steel ball of standard dimensions is forced into the surface of the test specimen in two consecutive loads and the depth of indentation is measured which is taken as measure of hardness.APPARATUS AND MATERIALS:- A) Brinell hardness test i) Brinell hardness testing materials with or without microscope ii) Measuring instrument to measure the diameter of the indentation. The hard steel balls as indentators may be of varying sizes, 10mm, 5mm, 2.5mm. the loads to be applied with the balls shall be Diameter Load 10 mm 3000kg 5mm 750kg 2.5mm 187.50 kg B) Rockwell hardness test:- Rockwell hardness testing machine with the indentators.i) Conical diamond indentator, in the form of right circular cone with an included angle of 1200, tip rounded to the 0.2 mm radius. ii) Hardened and polished steel ball of diameter 1.5875 mm made of hardened steel of hardness 850HV. Two scales C scale and B scale are used for measuring indentation .The C scale is used for diamond penetrator and B scale is used in case of steel ball indentator. The scale reads indentation in units of 0.002mm.

MATERIAL:- Specimens for testing should have smooth surface, the thickness of the specimen being at least 8 times the indentation.PROCEDURE:- Brinell hardness test:- 1) Carry out test at room temperature between 100 to 350 C.2) Place the test piece on a horizontal platform, just under the indenting steel ball touching the specimen. Apply load slowly is 2 to 8 seconds time, maintain load for 10 to 15 seconds. 3) Remove the load.4) Measure the diameter of indentation with the help of microscope or a suitable measuring device, in two directions at right angles and take arithmetic means of two.5) Record the load (P), the diameter of ball (D) and diameter of indentation (d) 6) The distance between any indentation and the edge of the test specimen shall be minimum 2.5 times the indentation and the distance between centers of two adjacent indentations shall be minimum 4 times the dia. of the indentation. Rockwell hardness test:-1) Place the specimen on the horizontal platform so as to be in contact with the indentator.2) Apply the minor load of 10 kg by raising the platform.3) Set the dial of the indicator of the depth gauge of suitable scale, as the initial position. Apply major load without shock within 2 to 8 seconds, value of load shall be 140 kg for diamond cone , 90 kg for ball, this load is in addition to the initial mirror load of 10 kg.4) Maintain the load till the indicator stops moving.5) Remove the major load.6) Record the indentation e of appropriate scale and calculate the Rockwell hardness number 7) During test take same precaution as under Brinell test.

OBSERVATION AND CALCULATION:

RESULT:- 1) The Brinell hardness number of material _________ kg/mm to _______kg /mm.2) The Rockwell hardness number of the material ___________ to _________

EXPERIMENT NO.:- 06

TITLE:- Compression test on metals.PURPOSE AND DISCUSSION:- The purpose of this test is to observe the behavior of metals under compression. Mild steel is ductile, hence does not fail into pieces, shows large deformation where as brass or cast iron is brittle, hence fails into two pieces. APPARATUS AND MATERIALS:-a) Mild steel specimen of size.1) Diameter = 16mm height = 10mm.2) Diameter = 16mm height = 50mm.

PROCEDURE:- 1) Place the specimen on the bottom cross head of U.T.M.2) Attach the magnetic base dial gauge at the bottom cross head of U.T.M. to measure the axial deformation in the mild steel specimen.3) Apply the load at the constant rate and record the deformation on at an interval of 1000kg. Till permanent deformation is observed for cast iron /brass specimen applying the load till the specimen fails in to two pieces.4) Repeat the procedure for remaining specimen. OBSERVATION AND CALCULATION:-Sr.No.Description of specimen.Load (kg)Load (N)Remark

1

2

CONCLUSION:- Mild steel is ductile metal hence does not fail into pieces. The specimen which is greater in height shows the tendency of bulking and that of lesser height is found to bulge for same load. Deformation is more in specimen 2 in specimen 1.

EXPERIMENT NO.:- 07TITLE: - Impact test on metals.i) Izod impact test.ii) Charpy impact test.PURPOSE AND DISCUSSION:- PURPOSE:- The purpose of this test is to study the toughness of materials. Toughness means the ability of the materials to absorb energy during the plastic deformation when subjected to suddenly applied loads.IMPACT STRENGTH:- 1) It is the resistance of material to shock or suddenly applied load. It is equal to the work performed in breaking a specimen in a testing machine. Brittle materials have low toughness since they have only small plastic deformation before failure. Thus they absorb very little energy before failure and so are dangerous if used in structures. Ductile materials absorb considerable energy before they break and so are comparatively tougher, thus ductile material has greater resistance to shock loading.2) Other tests such as tensile test, compression test etc.are conducted using gradually applied loads. In practice we become across some loads which are suddenly applied. The stress induced due to impact loads is higher than those in case of gradually applied loads. Thus structural members who are safe to bear gradually applied loads may fail under impact loads due to development of higher stresses. Impact may be in tension or compression or shear or in bending.3) The impact strength also depends upon temperature. The strength at zero temp. and at very high temp, are required in some casesMethods of impact test:- Impact tests are based on the following principals.i) The amount of energy absorbed by material before breaking under impact loading depends upon the nature of the metal. ii) If the specimen with the notch is tested in impact test instead of prismatic specimen without notch, much less energy is required to break the specimen.Test with notched specimen:- Thus in impact test, test pieces with a notch cut at a suitable section , is subjected to a hammer blow, so as to ensure that the specimen fails at the notch under a single blow. The energy required to break the specimen is a measure of impact strength. Test with Un-notched specimen:- Impact tests can also be conducted on un-notched specimen. In un-notched specimens there is no concentration of stress as in case of notched specimen, and the test determines the energy required in rupturing the un-notched specimen. The test is suitable for brittle material like cast iron whether the Izod impact method is used or Charpy impact is used, the cast iron test specimens are un-notched. Out of many impact tests devised, two tests are generally employed:-1) Izod test 2) Charpy test IZOD TEST:- In this test a pendulum which acts as a swinging hammer strikes a cantilever specimen gripped vertically with bottom of the notch at the same plane the upper face of the grips of vice and breaks it in one blow. The energy absorbed is observed. The testing machine consists of a heavy frame with a heavy pendulum weight supported at the top of the frame. The pendulum can be clamped at the certain height above the specimen and released for the striking. The striking energy should be 16.56kg.m. The energy is read on a circular scale at the top on which a pointer moves as the pendulum on either side of the specimen. The specimen is a square rod 10mm10mm75mmlong as shown in the figure. A V-notch is made at 28mm from one end. Depth of notch is 2mm and the internal angle of V is 450, with a root radius of 0.25mm. The specimen is fixed in a vice with a notch facing the hammer blow and level with an parallel to the top face of vice, with top at 28mm from the vice. As per I.S. 1958-1877 the weight of the base and its foundation shall be at least 40 times that the weight of the hammer. The plane of swing of the hammer shall be perpendicular to the vice. Figure shows how the specimen is fixed in the vice. The distance between the base notch and the point of the specimen hit by hammer shall be 22mm. The angle of the tip of the hammer shall be 750 and the angle between normal to the specimen and the underside the face of the hammer at the striking point shall be 100. The energy absorbed is the initial energy of the hammer before striking minus the final energy remaining in the hammer after it breaks the specimen, as indicated by rise of the hammer by swinging to the other side.CHARPY TEST:- In this test a beam type specimen with the notch at the center of the span simply supported at the ends is used. A hammer strikes the specimen on the face opposite the notch with certain energy to break the specimen in one blow. The energy absorbed is measured. The specimen is 10mm10mm55mm long. In the center of one face there is a U-notch 5mm deep with a root radius of 1mm. The specimen is fixed in the machine as a simples beam with clear distance between the supports 40mm. The hammer strikes the face opposite the notch with the speed of 5 to 5.5m/s and energy equal to the 30kg.meters. The angle at the tip of the hammer is 300 and the radius of curvature is 2mm. the radius of the curvature of the supports is 1mm and the topper of supports is 1.5. the planes of the swing of the hammer should be vertical and midway between the supports. In the other respects the operation of the machine is similar to Izod machine. APPARUTUS:- (A) Izod test : Izod impact testing machine scale (B) Charpy test Chappy impact testing machine scale

MATERIALS:- A) Izod test:- The test specimen 10mm10mm75mm long with the V- notch of 450, 2mm deep and a root radius of 0.25 at a distance of 28mm from one end. Notch axis should be at right angles to the longitudinal axis of the specimen.B) Chapy test:- Test specimen10mm10mm55mm long with a U-Notch at 27.5mm from ends, 5mmdeep and a root radius of 1mm. Notch axis should be at right angles to the longitudinal axis of the specimen

PROCEDURE:- A) Izod test:- i) Fix the pendulum weight with the flat striking surface. Bring it up and clamp.ii) Fix the specimen for the Izod test in the vice at the base with the notch facing the blow of the hammer and at the distance of the 28mm from top with the plane of the symmetry in the same plane as of the top of vice. In this position the pendulum will strike at 6mm from the top.iii) Adjust the pointer on the scale to the zero.iv) Release the pendulum from the clamp.v) The pendulum will strike the specimen and break it and swing to other side up due to some energy still left. After the pendulum rises to the highest point on the other side. The pointer on the scale will read the energy absorbed by the specimen. This reading in kg. meters. Is the impact strength of the specimen and is noted.

B) Charpy test:- i) Fix the hammer used for charpy test. Bring it up to ensure energy of 30 kg.meters. and clamp.ii) Place the specimen for Charpy test as described earlier, squarely against supports with the notch on opposite side of the hammer blow. The plane of symmetry of the notch should be in the plane of the swing of the hammer iii) Adjust the scale to zero.iv) Release the hammer from the clamp.v) The hammer will break the specimen and will rise on either side and come break. Note down the reading on the scale at the time of highest rise on the other side. It indicates the impact strength of the Charpy test.

OBSERVATIONS:- Sr.No.Material of specimenImpact strength (kg.m.)Remark

Izod (kg.m)Charpy kg.m.)

1Copper

2Brass

3Mild Steel

Dimensions of the specimen. Izod test: BWL Charpy test: BWL

OBSERVATION TABLE :

RESULT:- Impact strength is as shown in the above table.Advantages of Charpy Test:- It is more convenient and useful for the tests at high as well as low temperatures as the specimen do not have to be clamped and can be placed in position quickly without significant change of temperature. It takes comparatively more time to fix the specimen in the Izod test than in Charpy test.

EXPERIMENT NO. 08TITLE:- Flexural test on the Flooring tiles.AIM:- To determine transverse strength (flexural Strength) of i) Flooring tiles cement concrete flooring tiles.PURPOSE:- The purpose of the test is to have an idea of quality of tiles along with the water absorption test, we can judge the quality of the tiles tested. TRANSVERSE STRENGTH:- The strength in bending is called as the transverse strength or the flexural strength. Tiles are much thinner as compared to bricks or cement concrete blocks and so their strength is measured by breaking them by applying the bending load instead of a compression load or tensile load. While using the roofing tiles they are supported on wooden battens and so are subjected to bending also floor tiles, which are laid on the mortar, may be unevenly supported by the mortar and would be subjected to bending. TEST:- In the test wet tiles are tested placing them on steel rollers and loading the same on mid span through similar rollers, as per latest I.S. Recommended, only wet tiles are to be tested by soaking them into water and dry tiles are not to be tested as per these specifications.APPARATUS:- 1) Flexural tiles testing machine.2) Lead shots.3) Weighing balance. The flexural testing machine has two parallel self aligning cylindrical steel bearers. The bearing surface is rounded to 40mm dia. for testing of Mangalore tiles. For testing of flooring tiles the rollers may be 20mm dia. The distance between the rollers can be adjusted. The load is applied through the third roller of the same shape and placed midway between the supports on the tiles. The length of the all the bearers shall be more than maximum width of the tile to be tested. The loading is done through a bucket which can be gradually filled with the lead shots and connected to the loading bears through the levers.MATERIALS:- 1) 3 cement concrete flooring tiles. 2) 3mm 20mm plywood strips.PROCEDURE:- i) Select six tiles to be representative of the lot of the tiles manufactured. Soak the tiles in the water for 24 hours at a temperature of 270 C 20C ii) Support the tiles flat wise on the bearers (rollers) with sides parallel to the supports. In case of the Mangalore tiles keep the span of 25cm and the tiles should rest with the bottom surface on the rollers. In case of the cement concrete flooring tiles place the tiles with the bearing surface upwards and keep the span as follows:- The size (mm) Span (mm) 250250 200iii) Apply the load at the uniform rate of 45kg to 55kg/min, allowing the lead shots to flow in bucket.iv) Apply the load till the specimen breaks.

OBSERVATION TABLE:- Sr.No.Span (l)Width (b)Thickness (t)Breaking load (p)(N)F (N/mm2)Average(N/mm2)

1

2

3

CALCULATIONS:-

RESULT:- Cement concrete flooring tiles. Average of transverse strength

CONCLUSION:- The cement concrete flooring tiles tested satisfy the I.S. requirement.