CE6411 STRENGTH OF MATERIALSLABORATORY GKM COLLEGE OF ENGINEERING AND TECHNOLOGY DEPARTMENT OF AERONAUTICAL ENGINEERING MULLAINATHAN.N 1 ACKNOWLEDGEMENT I sincerely thank our respected chairman, Dr. G.KATHAMUTHU, G.K.M Group of Educational Institutions for all his efforts and administrations in educating us in his prestigious institution. I take this opportunity to thank our CEO, Dr.SUJATHA BALASUBRAMANIAN, MBA., Ph.D ., for the kind cooperation in helping us to complete this manual. I express my sincere thanks to our Director, Dr.K.JAGANATHAN, M.Tech., Ph.D., for providing appropriate facilities for completing this manual. I wish to extend my grateful acknowledgment and sincere thanks to my Head of Department Dr. J.V.SAI PRASANA KUMAR ,Ph.D., for his constant motivation encouragement and criticism in completing this manual. 2 LIST OF EXPERIMENTS 1. Tension test on mild steel rod 2. Compression test on wood 3. Double shear test on metal 4. Torsion test on mild steel rod 5. Impact test on metal specimen (Izod and Charpy) 6. Hardness test on metals (Rockwell and Brinell Hardness Tests) 7. Deflection test on metal beam 8. Compression test on helical spring 3 Mild steel specimens iii. Universal Testing Machine (UTM) ii. Vernier Caliper DIAGRAM 4 . Young’s modulus of elasticity vi. Deflection test on carriage spring 10. Percentage elongation vii. APPARATUS i.9. Limit of proportionality ii. Test on Cement Ex. Percentage reduction in area. Scale v. Graph paper iv. Ultimate strength v. Elastic limit iii. Yield strength iv.No 1 Tensile test on a metal AIM To conduct a tensile test on a mild steel specimen and determine the following i. some materials do not exhibit a sharp yield point. reaches a maximum value. of all mechanical tests. The stress below which the deformations essentially entirely elastic is known as the yield strength of material. As elastic and the rest of the curve which represents the manner in which solid undergoes plastic deformation is termed plastic. This stage the “ultimate strength”’ which is defined as the ratio of the load on the specimen to original cross-sectional area. In this test ends of test piece are fixed into grips connected to a straining device and to a load measuring device. if the load is too large. However. the deformation of any solid body is entirely elastic. In some material the onset of plastic deformation is denoted by a sudden drop in load indicating both an upper and a lower yield point.Tensile Testing Material ] THEORY The tensile test is most applied one. If the applied load is small enough. at larger extensions strain hardening cannot compensate for the decrease in section and thus the load passes through a maximum and then begins to decrease. However. the material can be deformed permanently. PROCEDURE 5 . Further loading will eventually cause ‘neck’ formation and rupture. During plastic deformation. An elastically deformed solid will return to its original from as soon as load is removed. The initial part of the tension curve which is recoverable immediately after unloading is termed. OBESERVATION A) Original dimensions Length = -----------Diameter = --------Area = -------------B) Final Dimensions Length = ------------------Diameter = ----------------Area = -----------------------OBESERVATION TABLE S. 7. 4. 3. The length may either be length of gauge section which is marked on the specimen with a preset punch or the total length of the specimen. Continue the test till Fracture occurs.NO Load (N) Original Gauge Extension (mm) Length 1 2 3 4 5 6 . 6. 2. By joining the two broken halves of the specimen together. Measure the original length and diameter of the specimen.1. 5. Insert the specimen into grips of the test machine and attach strain-measuring device to it. measure the final length and diameter of specimen. Begin the load application and record load versus elongation data. Measure elongation values with the help of dividers and a ruler. Take readings more frequently as yield point is approached. MODEL GRAPH RESULT i) Average Breaking Stress = ii) Ultimate Stress = iii) Average % Elongation = PRECAUTION 7 . Measure deflection on scale accurately & carefully Ex. Vernier calipers. But ductile materials like Aluminum and mild steel which are strong in tension are also tested in compression. Hence this test is normally performed on cast iron. APPARATUS:Universal compressive testing machine (UTM). 2. which are good in tension are poor in compression. If the strain measuring device is an extensometer it should be removed before necking begins. cement concrete etc. dial gauge. Compression test is just opposite in nature to tensile test.No2 AIM Compression test on wood To determine the compressive strength of given sample. Compressive load tends to squeeze the specimen. Cast iron is one such example. Several materials. THEORY:Structure components such as columns and struts are subjected to compressive load in applications. stop watch. 8 . This strength is determined by conducting a compression test. During the test. Not all the materials are strong in compression. Nature of deformation and fracture is quite different from that in tensile test.1. the specimen is compressed and deformation versus the applied is recorded. Many materials poor in tension are good in compression. These components are made of high compressive strength materials. Brittle materials are generally weak in tension but strong in compression. S. Determine percentage reduction in length (or height) to the specimen RESULT: 9 in . 3. Ultimate compressive strength = Force (N) just before rupture / (original c/s area) Percentage reduction in length = (initial length. Dimensions of test piece is measured at 3 different places along its height/length to determine the average c/s area. The load interval may be as 500kg. we can a.NO Applied Recorded Load (N) in length Change Stress=Load/area Strain=change length/original length 1 2 3 4 CALCULATION For compression test. For that the ends are tested on a bearing plate. b. Determine Young’s modulus in compression. Initial length or height of specimen h =______mm. The load and the corresponding contraction are measured at different intervals. Draw stress-strain (a-s) curve in compression. c.Formulae Young’s modulus = slope of stress Vs Strain. The specimen is placed centrally between the two compressions plates. 4. 6. OBSERVATION: 1. 2. 5. Load is applied until the specimen fails. such that the center of moving head is vertically above the center of specimen. Ends of the specimen should be plane. PROCEDURE 1. Load is applied on the specimen by moving the movable head.) compressive strength. and d. Determine ultimate (max.final length)*100/initial length. Take reading carefully. Specimens DIAGRAM 10 . After failed specimen stop to m/c. The specimen should be prepared in proper dimensions. APPARATUS i. The specimen should be properly to get between the compression plates. d. Ex. Universal testing machine. b. ii. Shear test attachment.N/mm2 PRECAUTIONS a. c. iii.No 3 Double Shear Test on Metal AIM To conduct shear test on specimens under double shear.The compressive strength of given specimen =——————. If the specimen breaks in two pieces then it will be in single shear & if it breaks in three pieces then it will be in double shear. Stop the machine and remove the specimen Repeat the experiment with other specimens. 2. Select the suitable range of loads and space the corresponding weight in the pendulum and balance it if necessary with the help of small balancing weights. 6. Operate (push) buttons for driving the motor to drive the pump. Down the load at which the specimen shears. 8. 3. The drag indicator in contact with the main indicator. this attachment consists of cutter.THEORY Place the shear test attachment on the lower table. PROCEDURE: 1. Switch on the main switch of universal testing machine. 11 . The specimen is inserted in shear test attachment & lift the lower table so that the zero is adjusted. then apply the load such that the specimen breaks in two or three pieces. 4. 5. Insert the specimen in position and grip one end of the attachment in the upper portion and one end in the lower portion. 7. Gradually move the head control level in left-hand direction till the specimen shears. A torsion testing machine. 2. 2. 12 . Measure the diameter of the specimen accurately. mm2 Load taken by the Specimen at the time of failure . 3.. Ex. mm Cross-section area of the Rod (in double shear) = 2x π/4x d2 =. AIM To conduct torsion test on mild steel or cast iron specimens to find out modulus of rigidity APPARATUS 1. A steel rule and Vernier Caliper or micrometer.OBESERVATION:Diameter of the Rod. W = N Strength of rod against Shearing = ƒx2x π/4x d2 ƒ = W / 2x π/4x d2 N/mm2 RESULT: The Shear strength of mild steel specimen is found to be= ……………… N/mm2 PRECAUTION 1 The measuring range should not be changed at any stage during the test.No 4 Torsion test on mild steel rod. D = …. The inner diameter of the hole in the shear stress attachment should be slightly greater than that of the specimen.. Twist meter for measuring angles of twist 3. = Polar moment of inertia. C = Modulus of rigidity. and l = Length of the shaft q = Shear stress 13 . θ = Angle of twist (radians). T = Torque applied.DIAGRAM:- Torsion Testing Machine THEORY: A torsion test is quite instrumental in determining the value of modulus of rigidity of a metallic specimen. The value of modulus of rigidity can be found out thought observations made during the experiment by using the torsion equation Where. Carry out straining by rotating the handweel in either direction. 9. 2. Read off co-ordinates of a convenient point from the straight line portion of the torque twist (T.r = Distance of element from center of shaft PROCEDURE 1. OBESERVATION TABLE Torque (T) Angle 1 2 3 4 5 6 7 of Twist (θ) in Radians 14 8 9 10 11 12 13 14 15 . Load the machine in suitable increments. Then load out to failure as to cause equal increments of strain reading. Select the driving dogs to suit the size of the specimen and clamp it in the machine by adjusting the length of the specimen by means of a sliding spindle. Measure the diameter at about three places and take the average value. 3. Plot a torque. 10. Set the maximum load pointer to zero.θ) graph. 7. Set the protector to zero for convenience and clamp it by means of knurled screw.twist (T. l = ……… Diameter of the specimen.θ) graph and calculate the value of C by using relation OBESERVATION Gauge length of the specimen. Choose the appropriate range by capacity change lever 4. 6. 8. d = ……… Polar moment of inertia. 5. No 5 Impact test on metal Specimen AIM To determine the impact strength of steel by Izod and Charpy impact test APPARATUS 1.N/mm2 PRECAUTION 1) Measure the dimensions of the specimen carefully 2) Measure the Angle of twist accurately for the corresponding value of Torque. Impact testing machine 2. Ex. A steel specimen 75 mm X 10mm X 10mm 15 .Modulus of Rigidity(C) RESULT i) Modulus of rigidity of mild steel rod is ------------.N/mm2 ii) Modulus of rigidity of Aluminum rod is ------------. Several engineering materials have to withstand impact or suddenly applied loads while in service.DIAGRAM IZOD TEST CHARPY TEST \THEORY An impact test signifies toughness of material that is ability of material to absorb energy during plastic deformation. Static tension tests of unnotched specimens do not always reveal the susceptibility of a metal to brittle fracture. This important factor is determined by impact test. Toughness takes into account both the strength and ductility of the material. Impact strengths 16 . With the striking hammer (pendulum) in safe test position. Therefore. Then it continues to swing. while the pendulum falls back. At its topmost height after breaking the specimen. Bring indicator of the machine to zero. the notch bar tests are most extensively used. the total energy is not absorbed by the specimen. Note the indicator at that topmost final position. 17 . 5. With the striking hammer (pendulum) in safe test position. or follow the instructions of the operating manual supplied with the machine. The test measures the notch toughness of material under shock loading. firmly hold the steel specimen in impact testing machine’s vice in such a way that the notch face the hammer and is half inside and half above the top surface of the vice. This test can also be used to assess the ductile brittle transition temperature of the material occurring due to lowering of temperature. PROCEDURE (a) lzod test 1. Again bring back the hammer to its idle position and back. firmly hold the steel specimen in impact testing machines vice in such a way that the notch faces s the hammer and is half inside and half above the top surface of the vice. 2. 3. Still it is important to note that it provides a good way of comparing toughness of various materials or toughness of the same material under different condition. Values obtained from these tests are not of much utility to design problems directly and are highly arbitrary. and lock it at that position. the indicator stops moving.are generally lower as compared to strengths achieved under slowly applied loads. (b) Charpy Test 1. 4. It will fall due to gravity and break the specimen through its momentum. Release the hammer. the impact test measures the energy necessary to fracture a standard notch bar by applying an impulse load. Of all types of impact tests. Bring the striking hammer to its top most striking position unless it is already there. OBESERVATION a)Izod Test S. 3.No Initial Energy(E1) Residual Energy(E2) Absorb Energy (E1-E2) Residual Energy(E2) Absorb Energy (E1-E2) b) Charpy Test S. 4. At its topmost height after breaking the specimen.No Initial Energy(E1) Modulus of Rupture= Rupture/Effective Volume of Specimen Notch Impact Strength = Absorb Energy/ Effective cross sectional Area RESULT a) Izod Test The impact Strength of the specimen = J/mm 2 b) Charpy Test The impact Strength of the specimen = J/mm 2 PRECAUTION 1. Measure the dimensions of the specimen carefully. The specimen is placed on supports or anvil so that the blow of hammer is opposite to the notch.2. and lock it at that position. It will fall due to gravity and break the specimen through its momentum. Note the indicator at that topmost final position. Then it continues to swing. or follow the instructions of the operating manual supplied with the machine. while the pendulum falls back. 18 . 5. the total energy is not absorbed by the specimen. Bring the striking hammer to its top most striking position unless it is already there. Release the hammer. Bring indicator of the machine to zero. the indicator stops moving. 3. Note down readings carefully. Ex. Hold the specimen firmly. carbon steel.No 6 Hardness Test on metals AIM To conduct hardness test on mild steel. brass and aluminum specimens.2. 19 . soft and hard mild steel specimens. The indenters usually a ball cone or pyramid of a material much harder than that 20 . Rebound hardness measurement c. Hardness tests provide an accurate. rapid and economical way of determining the resistance of materials to deformation. DIAGRAM Hardness Testing Machine THEORY The hardness of a material is resistance to penetration under a localized pressure or resistance to abrasion. Indention hardness measurement. There are three general types of hardness measurements depending upon the manner in which the test is conducted: a. In rebound hardness measurement. Scratch hardness measurement. aluminum etc.APPARATUS Hardness tester. In scratch hardness method the material are rated on their ability to scratch one another and it is usually used by mineralogists only. a standard body is usually dropped on to the material surface and the hardness is measured in terms of the height of its rebound . b. brass.The general means of judging the hardness is measuring the resistance of a material to indentation. thick or thin metallic sheet. Here the indentor has a diamond cone at the tip and applied force is of 150 kgf. Steel indentor at 60kgf.Its specification are as follows: 1.120o 10 50 0 Much harder steels B Ball. Although there are many scales having different combinations of load and size of indentor but commonly ‘C’ scale is used and hardness is presented as HRC.5D2 load. the specimen may be a cylinder. A Brinell. Soft materials are often tested in ‘B’ scale with a 1. 5mm. The hardness of the material depends on the resistance which it exerts during a small amount of yielding or plastic. 10mm. Diameter of ball (as indentor) used D = 2.5mm.58mm 10 90 30 Soft steels. 2. viscosity and the intensity and distribution of plastic strain produced by a given tool during indentation. sintered tungsten carbide or diamond indenters are generally used in indentation tests. 3. Rockwell hardness tester presents direct reading of hardness number on a dial provided with the m/c. The resistance depends on friction. a load is applied by pressing the indenter at right angles to the surface being tested.W. principally this testing is similar to Brinell hardness testing. Maximum application load = 3000kgf. Scale Type of Indentor Initial Load Major Load Pointer Position Kind of Material A Cone. Insert ball of diameter ‘D’ in ball holder of the m/c. Rockwell hardness m/c or vicker testing m/c. Ability to determine hardness upto 500BHN. A hardness test can be conducted on Brinell testing m/c. 4. It differs only in diameter and material of the indentor and the applied force. Hardened steel. elasticity.etc PROCEDURE 1.cum-Rockwell hardness testing m/c along with the specimen is shown in figure.1. 21 . cube. Various scale in Rockwell Hardness test are given below. Copper . Aluminum C Cone.120o 10 140 0 Hard Steels like Ti.Va. Capability of testing the lower hardness range = 1 BHN on application of 0.being used. Method of load application = Lever type 5.6mm dia. 002) RESULT Brinell hardness number of the specimen is -------22 . 3-times. 6. • Test piece material =----------• HRA = 100-(t/0. Repeat the entire operation.) BHN= 2P/πD(D-√D2 – d2) (b) Rockwell Hardness Test Following observation are recorded are from a test on steel specimen using a hardened steel ball as indentor. 4. 7.No Ball Diameter D (mm) Load Applied P(N) Diameter of Indentation BHN d(mm) BHN = Load Applied (kgf. Make the specimen surface clean by removing dust. Make contact between the specimen surface and the ball by rotating the jack adjusting wheel.2. 8. 3. 5. Test piece material = --------------S. oil and grease etc. Push the required button for loading. Remove the specimen from support table and locate the indentation so made.002) • HRC = 100-(t/0. OBSERVATION AND CALCULATION (a) Brinell Hardness Test Following observation are recorded from a test on steel specimen using a hardened steel ball as indentor.002) • HRB = 130-(t/0.)/ Spherical surface area indentation (in mm. dirt. View the indentation through microscope and measure the diameter‘d’ by micrometer fitted on microscope. Pull the load release level and wait for minimum 15 second. The load will automatically apply gradually. 4. 3.No7 Deflection Test on metal beam .Rockwell hardness of given specimen is -------PRECAUTIONS 1. Take reading more carefully and correct. 2.AIM 23 . Ex. Jack adjusting wheel move slowly 5. Place the specimen properly. After applying load remove the load. The specimen should be clean properly. 24 . the beam bends concave upwards. Deflection of beam apparatus 2.To find the values of bending stresses and young’s modulus of elasticity of the material of a beam simply supported at the ends and carrying a concentrated load at the centre. The distance between the original position of the beams and its position after bending at different points along the length of the beam. Beam of different cross-sections and material DIAGRAM Beam Deflection Test Apparatus THEORY If a beam is simply supported at the ends and carries a concentrated load at its centre. being maximum at the centre in this case. Pan 3. APPARATUS 1. Weights 4. This difference is known as ‘deflection’ In this particular type of loading the maximum amount of deflection (δ) is given by the relation. iron block along the bed so that they are symmetrical with respect to the length of the bed. 6. N/mm2 I =Second moment of area of the cross. On the graph choose any two convenient points and between these points find the corresponding values of W and δ. N-mm I = Moment of inertia. Draw a graph between load (W) and deflection (δ) . 4. = Bending stress. See that the load is applied at the center of the beam 3. Find the deflection (δ) in each case by subtracting the initial reading of Vernier scale. Putting these Values in the relation 8. Note the initial reading of Vernier scale. and Y = Distance of the top fiber of the beam from the neutral axis PROCEDURE 1. M = Bending moment. Calculate the bending stresses for different loads using relation 25 . Place the beam on the knife edges on the block so as to project equally beyond each knife edge.W =Load acting at the center. Add a weight of 20N (say) and again note the reading of the Vernier scale. about the neutral axis. mm BENDING STRESS Where. N L =Length of the beam between the supports mm E =Young’s modulus of material of the beam. Adjust cast. Go on taking readings adding 20N (say) each time till you have minimum six readings. 5. . 2. 7.section ( moment of Inertia) of the beam. ii. PRECAUTION 1. A spring Modulus Elasticity M= 1 Ex. The young’s modulus for metal beam is found to be-----.NO Load W(N) Bending Bending Moment Stress Deflection 2 3 4 5 RESULT 1. The cross.section of the beam should be large. 2.OBESERVATION TABLE S. Make sure that beam and load are placed a proper position.No8 Young’s 26 of . Spring testing machine. Note down the readings of the Vernier scale carefully Compression Test on Helical Spring AIM To determine the stiffness of the spring and modulus of rigidity of the spring wire APPARATUS i. 3.. iii. governors etc. motorcycles. Micrometer. scooters. rickshaws. They are used in railway carriages. motor cars. 2) To store energy as in clock springs. 27 . DIAGRAM THEORY Springs are elastic member which distort under load and regain their original shape when load is removed. Scale. Vernier caliper. iv. According to their uses the springs perform the following Functions: 1) To absorb shock or impact loading as in carriage springs. PROCEDURE 1) Measure the diameter of the wire of the spring by using the micrometer. d =………mm (Mean of three readings) Least count of Vernier caliper = ……mm Diameter of the spring coil. n = OBESERVATION TABLE 28 . leaf springs and flat spring depending upon their shape.7 to 1. 4) To measure forces as in spring balances. 6) Plot a curve between load and deflection. Phosphor bronze. D = ……mm (Mean of three readings) Mean coil diameter. 2) Measure the diameter of spring coils by using the Vernier caliper 3) Count the number of turns. 5) To change the variations characteristic of a member as in flexible mounting of motors. They are fabricated of high shear strength materials such as high carbon alloy steels spring form elements of not only mechanical system but also structural system.3) To apply forces to and to control motions as in brakes and clutches. 18/8 stainless steel and Monel and other metal alloys are used for corrosion resistance spring. 4) Insert the spring in the spring testing machine and load the spring by a suitable weight and note the corresponding axial deflection in tension or compression. The shape of the curve gives the stiffness of the spring. In several cases it is essential to idealize complex structural systems by suitable spring. = D . The spring is usually made of either high carbon steel (0. Several types of spring are available for different application. 5) Increase the load and take the corresponding axial deflection readings. OBESERVATION Least count of micrometer = ……mm Diameter of the spring wire. Springs may classified as helical springs.d……mm Number of turns.0%) or medium carbon alloy steels. brass. 2) Deflection obtained in spring was measured 29 .N / mm PRECAUTION 1) The dimension of spring was measured accurately.S.NO Load W (N) Deflection (mm) Stiffness K= Mean K= Modulus of Rigidity Spring Index = RESULT The value of spring constant k of closely coiled helical spring is found to be-----------. Find the actual deflection of the spring for each load by deducting the initial scale reading from the corresponding scale reading. 2.Ex. P = Load in N R = Mean radius of the spring in mm (D –d /2) d = Diameter of the spring coil in mm 30 . 4. 7.e. Fit the specimen in the top of the hook of the spring testing machine. Calculate the modulus of rigidity for each load applied by using the following formula: Modulus of rigidity. 8. Tension spring specimen 3. Where. 6. APPARATUS AND SPECIMEN REQUIRED 1. Spring test machine 2. Measure the outer diameter (D) and diameter of the spring coil (D) for the given tension spring.No 9 Deflection Test on Carriage Spring AIM To determine the modulus of rigidity and stiffness of the given tension spring specimen. Vernier caliper PROCEDURE 1. Count the number of turns i. Increase the load at the rate of 25kg up to a maximum of 100kg and note down the corresponding scale readings. coils (n) of the given specimen. Apply a load of 25kg and note down the scale reading. 3. Note down the initial reading from the scale in the machine. Adjust the wheel at the top of the machine so that the other end of the specimen can be fitted to the bottom hook in the machine. 5. No Kgf N 1 2 3 4 5 6 Result The modulus of rigidity of the given spring = -------------------N/mm2 The stiffness of the given spring = -------------------N/mm2 31 of Stiffness N/mm in . Determine the stiffness for each load applied by using the formula Stiffness. Diameter of the spring coil. Number of coils / turns. OBSERVATION 1. Find the values of modulus of rigidity and spring constant of the given spring by taking average values. 9. d = mm 4. Material of the spring specimen = 2.δ = Deflection of the spring in mm D = Outer diameter of the spring in mm. K = P/δ 10. n = Nos. D = mm 3. Initial scale reading = Applied Load mm Scale reading Actual Modulus in mm deflection rigidity in mm In N/mm2 S. Outer diameter of the spring. 5. APPARATUS Le-Chatelier apparatus conforming to IS 5514-1969.Ex.No 10 Test on cement AIM To determine the soundness of the given sample of cement by "Le Chatelier" Method and to determine the quantity of water required to produce a cement paste of standard consistency. DIAGRAM 32 . gauging trowel Balance. Water bath. weights. Vicat apparatus (conforming to IS: 5513 1976) with plunger (10 mm in diameter) balance. Weights. 33 . 34 . 78 times the water required to give a paste of standard consistency. The paste shall be gauged in the manner and under the conditions prescribed in determination of consistency of standard cement paste. 35 . This experiment is intended to find out the quantity of water to be mixed for a given cement to give a cement paste of normal consistency and can be done with the help of vicat apparatus. Unsoundness in cement does not come to surface for a considerable period of time. magnesia and sulphates in cement which are the causes of the change in volume known as unsoundness.INTRODUCTION It is essential that the cement concrete shall not undergo appreciable change in volume after setting. On either side of the split mould are attached to indicators with pointed ends. soundness of cement and compressive strength of cement. While this operation is being performed cover the mould with another piece of glass sheet. The standard consistency of a cement paste is defined as that consistency which will permit the vicat plunger to penetrate to a point 5 to 7 mm from the bottom of the vicat mould. distortion and disintegration there by giving passage to water and atmospheric gases which may have injurious effects on concrete and reinforcement. Unsoundness produces cracks. This is ensured by limiting the quantities of free lime. PROCEDURE (a) To determine the soundness of the given sample of cement 1. the distance from these ends to the center of the cylinder being 165 mm. taking care to keep the edges of the mould gently together 3.20 C and keep there for 24 hours.5mm thickness forming a mould 30 mm internal diameter and 30mm high. For finding out initial setting time. place a small weight on this covering glass sheet and immediately submerge the whole assembly in water at a temperature of 27 0 . 2. it is necessary to fix the quantity of water to be mixed in cement in each case. The apparatus for conducting the test consists of small split cylinder of spring brass or other suitable metal of 0. This test is designed to accelerate the slaking process by the application of heat and discovering the defects in a short time. The mould shall be kept in good condition with the jaws not more than 50mm apart. Place the lightly oiled mould on a lightly oiled glass sheet and fill it with cement paste formed by gauging cement with 0. final setting time. trim off the surface of the paste. allowing it to penetrate into the paste. Remove the mould from the water allow it to cool and measure the distance between the indicator points. and keep it boiling for three hours. 8. 7. lower the plunger gently to touch the surface of the test block and quickly release. Take care that the time of gauging is not less than 3 minutes. 4. Prepare a paste of weighed quantity of cement (300 grams) with a weighed quantity of potable or distilled water. 36 . Fill the vicat mould with this paste. 3. 5. The gauging time shall be counted from the time of adding the water to the dry cement until commencing to fill the mould. The mould may slightly be shaken to expel the air. 8. under the rod bearing the plunger (10mm diameter). This operation shall be carried out immediately after filling the mould. 9. with the mould kept submerged for 25 to 30 minutes.4. together with the non-porous resting plate. Submerge the moulds again in water at the temperature prescribed above. the mould resting upon a non porous plate. The difference between these two measurements represents the expansion of the cement. not more than 5 minutes and the gauging shall be completed before setting occurs. Prepare trial pastes with varying percentages of water and test as described above until the amount of water necessary for making the standard consistency as defined above is obtained. Place the test block with the mould. Bring the water to boiling. (b) To determine the quantity of water required to produce a cement paste of standard consistency 1. 6. making it in level with the top of the mould. Measure the distance separating the indicator points. 5. 6. 7. For good quality cement this expansion should not be more than 10mm. After completely filling the mould. 2. starting with 26% water of 300g of cement. 9. Express the amount of water as a percentage by weight of the dry cement. initial length = Sample 2 Initial distance between the indicator points in mm = Final distance between the indicator points in mm = Expansion in mm = final length .OBSERVATIONS (a) Soundness of cement Sample 1 Initial distance between the indicator points in mm = Final distance between the indicator points in mm = Expansion in mm = final length .initial length = Sample 3 Initial distance between the indicator points in mm = Final distance between the indicator points in mm = Expansion in mm = final length . No Weight of cement taken in gms (a) Weight of water taken in gms (b) Plunger penetration (mm) RESULT: The average Expansion in mm is ______________ Normal consistency for the given sample of cement is_______ 37 Time Taken Consistency of cement in % by weight b/a * 100 .initial length = (b) Normal consistency of cement S. The temperature of cement.PRECAUTIONS Clean appliances shall be used for gauging. at the time when the above operations are being performed. water and that of test room. 38 . For each repetition of the experiment fresh cement is to be taken. In filling the mould the operator hands and the blade of the gauging trowel shall alone be used. shall be 27 + 2 C.