Standard Test

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    29-Nov-2014

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Bulking of fine aggregateAim: To determine the percentage of bulky of fine aggregate. Apparatus: Cylindrical measuring jar,bowl,glass rod etc. Theory: The Volume of fine aggregate such as sand particles depends largely upon its moisture containment. If fine are met each particles gets a coat of water which is due to surface tension keeps them apart , and thus cause to increase in volume called bulking. Bulking increases gradually with moisture content . The increase being about 25% by volume as about 4% moisture content by weight then decreases to zero. Procedure: 1. Weigh out 500gm of sand, fill it in 1000 ml measuring jar note down the volume. 2. Transfer the sand to the basin and mix very well with 2% of moisture content by weight. 3. Fill the moisture to 1000 ml jar ,level the top surface with the glass rod note down the increase in volume. 4. Similarly repeat the procedure by adding 2% of moisture content by weight up to the decrease in volume. 5. Determine the percentage of bulky of fine aggregate. 6. Draw the variation for percentage of water added and increase or decrease. Observation: Sl No. 1 2 3 4 5 6 7 Volume of Sand (cc) 500 500 500 500 500 500 500 % of water 0 2 3 4 5 6 7 Increase/Decrease in water 680 830 860 910 930 910 860 % Bulky 36% 66% 72% 82% 86% 82% 72%Calculation: Bulking of sand= (H2-H1)/H1 =((930-500)/500)= 86% Result: The Percentage of bulky for fine aggregate is 86%.Sieve Analysis Aim: To determine the fineness modulus of the course aggregates. Apparatus: set of Is sieves,sample,balance with weights etc. Theory: The object of finding the fineness modulus is to grade the given aggregate for obtain most economical and workable mix with minimum quantity of cement.The aggregate fraction from 80mm-4.75mm are termed as coarse aggregates and those fractions from 4.75mm-150mm are termed as fine aggregates .The size of 4.7mm is a common fraction appearing both in coarse and fine aggregates. Procedure: Coarse aggregates: 1. Take about 5kg of road aggregates. 2. Put the aggregates in IS sieves i.e.. 80mm,40mm,20mm,10mm,4.75mm,2.36mm,1.18mm,600mm,150m, pan 3. Hold whole assembly in hand and shake it well or sieve for about 10min 4. Stop the sieving process and weight the mass retained on each sieve after cleaning the sieve with wire brush. 5. Calculate the cumulative % retained on each sieve and fineness modules. Observation: Sl No 1 2 3 4 5 IS sieve size in mm 40 20 12.5 10 4.75 Weight ratained in gms 0 4106 690 146 54 Cumulative wt retained in gms 0 4106 4796 4942 4996 Total Cumulative % wt retained 0 82.12 95.92 98.84 99.92 376.8 % fineness 0 17.88 4.08 1.16 0.08Calculation: Fineness modulus = sum finer / 100 = 376.8 / 100 = 3.768 D10 = 16mm D30 = 25mm D60 = 32mm Cc = (D30 * D30) / (D60 * D10) = (25 * 25) / (32 * 16) = 1.2207 Well graded Cu = D60 / D10 = 32 / 16 = 2 Result: 1. Fineness modulus of coarse aggregate = 3.768 2. Coefficient of curvature, Cc = 1.22 3. Uniformly Coefficient, Cu = 2Aggregate Impact TestAim: To determine the strength offered by the coarse aggregate under impact loads Apparatus:Impact testing machine IS sieve sizes of 2.36mm , 12.5mm , 10mm, balance, tamping rod Theory:The aggregate Impact value gives a relative measure of the resistance of all aggregate to sudden shock or impact which in some aggregate differ from its resistance to slow a compressive load with respect to concrete aggregate toughness is usually considered the resistance of the material to failure by impact several attempts to develop a method for aggregate impact value have been made .The most successful is the one in which a sample of std aggregate kept in a mould is subjected to 15 blows of a metal hammer of weight 14 kg falling from a height of 38 cm. the quantity of finer material results from powdering of aggregate. Procedure:1. The given aggregate sample is sieved through 12.5mm sieve and retained on 10mm IS sieve is taken out 2. The aggregate retained on 10mm IS sieve is taken and filled the cylinder on 3 equal layers giving 25 strokes on each layer by standard tamping rod and the sample surface is leveled off. Then the hammer is allowed to fall free on the aggregate from a height such that the lower end face of hammer is 38 cms above the upper surface of aggregate. 3. The Crushed aggregate is then removed from the cup and sieved through 2.36 mm sieve 4. The ratio of the weight of aggregate passing through 2.36 mm is sieve to the total weight of the aggregate in the cylinder gives the impact value of the aggregates. Observation: Sl No 1 2 3 4 Description Empty weight of mould W1 in gm Weight mould +Aggregates W2 in gms Weight of portion passing through 2.36 Crushing value =(W3/(W2-W1))x100 Weigjt 2000 2500 12 2.40%Calculation: Impact Value=(W3/(W2-W1))x100= (12/(2500-2000))x100= 2.4% Result: The aggregate impact value of a given coarse aggregate is 2.4% Conclusion:If the impact value is less than 10% it is considered as very strong 10% - 20% Strong 20% -30% is satisfactoryAbove30% Suitable for pavement construction.Crushing StrengthAim: To find the crushing strength of given coarse aggregates Apparatus: Compressing testing machine , Plunger , cylinder mould , IS sieve , weighting balance Theory: The aggregate crushing value gives a relative measure of the resistance of an aggregate to crushing under a gradually applied compressive load with aggregates of aggregates crushing value 30 higher the result may be in such cases the 10% fine value should be determined and used instead. The standard aggregates crushing test is made on aggregates passing a 12.5mmIS sieve and retained on 10mm IS sieve, if required or if the standard size is not available other size up to 25mm may be tested. Procedure: 1. The given aggregate sample is sieved through 12.5mm sieve and retained on 10mm IS sieve. 2. The aggregate retained on 10mm IS sieve is taken and filled the cylinder on 3 equal layers giving 25 strokes on each layer by standard tamping rod. 3. Leveled of the surface and top of the cylinder is covered by the plunger. 4. The whole assembly is kept under compressive testing machine. 5. The load is applied at the rate of 4 tones/min up to 40tonnes. 6. The cylinder is taken out from the plunger and the crushed aggregates to be 2.36mm ARE SIEVE. 7. The weight of the crushed aggregates passing through 2.36mm IS sieve is noted down. 8. The ratio of the weight of the aggregates passing through 2.36mm sieve to total weight of aggregates in the cylinder gives the crushing strength of aggregates. ie., crushing value = W3 / (W2-W1) Observation: Sl No. 1 2 3 4 Description Empty weight of crushing mould in gm Weight mould + Aggregates in gms Weight of portion passing through 2.36 Crushing value = W3 / (W2-W1*100) Weight 7200 9700 713 28.52Calculation: Time taken t=5 min Crushing value = W3 / (W2-W1*100) = 713 / (9700-7200*100) = 28.52%Result: The crushing strength of a given coarse aggregate = 28.52% Conclusion: The required crushing value for coarse aggregate for cement concrete pavement should not exceed 30% for granite.Elongation IndexAim: To determine the Elongation index of the given sample of coarse aggregates. Apparatus: IS sieve sizes of 63mm, 50mm, 40mm, 25mm, 20mm, 16mm, 10mm, 6.3mm, Pan, coarse aggregate sample, Balance. Theory: An aggregate having least dimension less than 3/5th of its mean dimension is termed flaky. where the mean dimension is the average of the sieve size through which the particles pass and the sieve size on which these are retained .on the other hand the particles having the largest dimension(length) greater than 9/5 times the mean size are termed elongated. The presence of excess of flaky and elongated particles in concrete aggregate decreases the workability appreciably for a given water-cement ratio thus requiring large amounts of sand, cement and water .The flaky and elongated particles and to orient in one plane and cause lamination which adversely affect the durability of the concrete. the percentage of flaky and elongated particles should be limited to 10 to 15. Procedure: 1. The set of sieve are arranged in decreasing order of their size I.e. 63mm sieve at top. 2. The sample of aggregate are sieved through these sieve. 3. Then Weight of aggregate retained on each sieve is noted with the help of balance. 4. In that retained aggregate the weight of the aggregate retained on gauge length (1.8 X mean size) is noted down. 5. The aggregate smaller than 6.3mm are not considered. 6. Then total of weight of aggregate retained on each sieve is calculated. 7. Similarly total of weight of aggregate retained on gauge length is also calculated. 8. Using formula elongation index is calculated.Observation:Passing thru Retained on Sl IS sieve size in sieve size in No. mm mm 1 50 40 2 50 25 3 25 20 4 20 16 5 16 10 6 10 8.3 7 8.3 8 TotalWeight aggregate in sieve 380 1330 480 1316 460 110 320 4396Weight of aggregate Elongation retained on gage Index length 244 380 33 104 18.76% 26 38 825 -Calculation: E.I = (Wt of retained in gauge length * 100) / Total weight of aggregate E.I = (825 * 100) / 4396 = 18.76% Result: Elongation index of Coarse aggregates=18.76% Conclusion: Since EI>15%, aggregate are unfit to use for pavement construction.Flakiness indexAim: To determine the flakiness index of the given sample of coarse aggregates. Apparatus:IS sieve sizes of 63mm,50mm,40mm,25mm,20mm,16mm,10mm,6.3mm,Pan,corase aggregate sample. Theory: An aggregate having least dimension less than 3/5th of its mean dimension is termed flaky. where the mean dimension is the average of the sieve size through which the particles pass and the sieve size on which these are retained .on the other hand the particles having the largest dimension(length) greater than 9/5 times the mean size are termed elongated. The presence of excess of flaky and elongated particles in concrete aggregate decreases the workability appreciably for a given water-cement ratio thus requiring large amounts of sand,cemet and water .The flaky and elongated particles tend to orient in one plane and cause lamination which adversely affect the durability of the concrete. The percentage of flaky and elongated particles should be limited to 10 to 15. Procedure:1. The set of sieve are arranged in decreasing order of their size I.e. 63mm sieve at top. 2. The sample of aggregate are sieved through these sieve. 3. Then Weight of aggregate retained on each sieve is taken with the help of balance. 4. In that retained aggregate the weight of the aggregate passing through thickness gauge (0.6Xmean size) is noted down. 5. The aggregate passing through 6.3 IS sieve are not considered. 6. Then total of weight of aggregate retained on each sieve is calculated. 7. Similarly total of weight of aggregate passing through thickness gauges is calculated. 8. Using formula flakiness index is calculated. Observation: Passing through IS sieve size in mm 63 50 40 25 20 12.2 10 4.75 Retained on sieve size in mm 50 40 25 20 12.5 10 4.75 Pan Total weight aggregate in sieve 440 380 1130 480 136 460 110 320 3456 Thickness gauge size mm 33.90 27.00 19.50 13.50 9.75 6.75 4.43 0 weight of aggregate Passing through the slot in gmSl No 1 2 3 4 5 6 7 8 954 18 274 154 195 46 741Calculation: F.I= (Sum (W1)/Sum (W)) x100= (741/3456)x100 Result: Flakiness of Coarse aggregates=20.26% Conclusion: Since FI>15%, aggregate are unfit to use for pavement construction. =20.26%DETERMINATION OF LOS ANGELES ABRASION VALUE AIM: (i) to determine the Los Angeles abrasion value. (ii) to find the suitability of aggregates for use in road construction. APPARATUS: The apparatus as per IS: 2386 (Part IV) 1963 consists of: (i) Los Angeles Machine: It consists of a hollow steel cylinder, closed at both the ends with an internal diameter of 700 mm and length 500 mm and capable of rotating about its horizontal axis. A removable steel shaft projecting radially 88 mm into cylinder and extending full length (i.e.500 mm) is mounted firmly on the interior of cylinder. The shelf is placed at a distance 1250 mm minimum from the opening in the direction of rotation. (ii) Abrasive charge: Cast iron or steel balls, approximately 48mm in diameter and each weighing between 390 to 445g; six to twelve balls are required. (iii) Sieve: 1.70, 2.36,4.75,6.3,10,12.5,20,25,40,50,63,80 mm IS Sieves. (iv) Balance of capacity 5kg or 10kg (v) Drying oven (vi) Miscellaneous like tray THEORY: The aggregate used in surface course of the highway pavements are subjected to wearing due to movement of traffic. When vehicles move on the road, the soil particles present between the pneumatic tyres and road surface cause abrasion of road aggregates. The steel reamed wheels of animal driven vehicles also cause considerable abrasion of the road surface. Therefore, the road aggregates should be hard enough to resist abrasion. Resistance to abrasion of aggregate is determined in laboratory by Los Angeles test machine. The principle of Los Angeles abrasion test is to produce abrasive action by use of standard steel balls which when mixed with aggregates and rotated in a drum for specific number of revolutions also causes impact on aggregates. The percentage wear of the aggregates due to rubbing with steel balls is determined and is known as Los Angeles Abrasion Value. PROCEDURE: The test sample consists of clean aggregates dried in oven at 105 110C. The sample should conform to any of the gradings shown in table 1. (i) Select the grading to be used in the test such that it conforms to the grading to be used in construction, to the maximum extent possible. (ii) Take 5 kg of sample for gradings A, B, C & D and 10 kg for gradings E, F & G.(iii) Choose the abrasive charge as per Table 2 depending on grading of aggregates. (iv) Place the aggregates and abrasive charge on the cylinder and fix the cover. (v) Rotate the machine at a speed of 30 33 revolutions per minute. The number of revolutions is 500 for gradings A, B, C & D and 1000 for gradings E, F & G. The machine should be balanced and driven such that there is uniform peripheral speed. (vi) The machine is stopped after the desired number of revolutions and material is discharged to a tray. (vii) The entire stone dust is sieved on 1.70 mm IS sieve. (viii) The material coarser than 1.7mm size is weighed correct to one gram.Sieve Weight of test sample in gm size (square hole) Passing Retained on (mm) (mm) 80 63 50 40 25 20 12.5 10 6.3 4.75 63 50 40 25 20 12.5 10 6.3 4.75 2.36 1250 1250 1250 2500 1250 2500 2500 2500 5000 A B C D E 2500* 2500* 5000* 5000* 5000* 5000* 5000* F GTable 1: Grading of Test Samples*Tolerance of 12 percent permitted. Grading A B C D E F G No of Steel balls Weight of charge in gm 12 11 8 6 12 12 12 5000 25 4584 25 3330 20 2500 15 5000 25 5000 25 5000 25Table 2: Selection of Abrasive Charge OBSERVATIONS: Original weight of aggregate sample = W1 g Weight of aggregate sample retained = W2 g Weight passing 1.7mm IS sieve = W1 - W2 g Abrasion Value = (W1 - W2 ) / W1 X 100 RESULT: Los Angeles Abrasion Value = SPECIFIC GRAVITY AND WATER ABSORPTION TEST AIM: i) To measure the strength or quality of the material ii) To determine the water absorption of aggregates APPARATUS: The apparatus consists of the following (a) A balance of capacity about 3kg, to weigh accurate 0.5g, and of such a type and shape as to permit weighing of the sample container when suspended in water. (b) A thermostatically controlled oven to maintain temperature at 100-110 C. (c) A wire basket of not more than 6.3 mm mesh or a perforated container of convenient size with thin wire hangers for suspending it from the balance.(d) A container for filling water and suspending the basket (e) An air tight container of capacity similar to that of the basket (f) A shallow tray and two absorbent clothes, each not less than 75x45cm. THEORY: The specific gravity of an aggregate is considered to be a measure of strength or quality of the material. Stones having low specific gravity are generally weaker than those with higher specific gravity values. PROCEDURE: (i) About 2 kg of aggregate sample is washed thoroughly to remove fines, drained and placed in wire basket and immersed in distilled water at a temperature between 22- 32 C and a cover of at least 5cm of water above the top of basket. (ii) Immediately after immersion the entrapped air is removed from the sample by lifting the basket containing it 25 mm above the base of the tank and allowing it to drop at the rate of about one drop per second. The basket and aggregate should remain completely immersed in water for a period of 24 hour afterwards. (iii) The basket and the sample are weighed while suspended in water at a temperature of 22 32C. The weight while suspended in water is noted =W1g. (iv) The basket and aggregates are removed from water and allowed to drain for a few minutes, after which the aggregates are transferred to the dry absorbent clothes. The empty basket is then returned to the tank of water jolted 25 times and weighed in water=W2g. . (v) The aggregates placed on the absorbent clothes are surface dried till no further moisture could be removed by this cloth. Then the aggregates are transferred to the second dry cloth spread in single layer and allowed to dry for at least 10 minutes until the aggregates are completely surface dry. The surface dried aggregate is then weighed =W3 g (vi) The aggregate is placed in a shallow tray and kept in an oven maintained at a temperature of 110 C for 24 hrs. It is then removed from the oven, cooled in an air tight container and weighted=W4 g. (1) Specific gravity = (dry weight of the aggregate /Weight of equal volume of water) (2) Apparent specific gravity = (dry weight of the aggregate/Weight of equal volume of water excluding air voids in aggregate) OBSERVATIONS Weight of saturated aggregate suspended in water with basket = W1 g Weight of basket suspended in water = W2 gWeight of saturated aggregate in water = W1 W2 g Weight of saturated surface dry aggregate in air = W3 g Weight of water equal to the volume of the aggregate = W3(W1W2)g Weight of oven dry aggregate = W4 g (1) Specific gravity = W3 / (W3 (W1 W2)) (2) Apparent specific gravity = W4 / (W4 (W1 W2)) (3) Water Absorption = ((W3 W4) / W4) X 100 RESULT: (1) Specific gravity = (2) Apparent specific gravity = (3) Water Absorption =

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