lecture notes and laboratory manual should be studied carefully and thoroughly. Tests on Concrete- Workability tests – Slump cone test, compaction factor test. Aurora's Technological & Research Institute. Concrete and Highway Engineering Lab. Department of Civil Engineering. 1. CT. LAB MANUAL. B. Tech III Year - I. independent and life-long learning in the broadest context of technological change – (Life- long learning). Page 5. v. FOREWORD. The concrete laboratory intends to train the students in the field of testing Concrete Lab Manual. Dept. of Civil.
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CONCRETE TECHNOLOGY. 1. DEPARTMENT OF CIVIL ENGINEERING. CONCRETE TECHNOLOGY LABORATORY. GUDLAVALLERU ENGINEERING. Concrete Lab Manual - Free download as PDF File .pdf), Text File .txt) or read online for free. computerescue.info (Civil)- Concrete Lab Manual as per R.T.U. Kota, Rajasthan. PDF | Concrete Technology is a preliminary subject in the undergraduate course of Bachelor of Technology programme of Civil Engineering.
Unsoundness in cement does not come to surface for a considerable period of time. This test is designed to accelerate the slaking process by the application of heat and discovering the defects in a short time. Unsoundness produces cracks, distortion and disintegration there by giving passage to water and atmospheric gases which may have injurious effects on concrete and reinforcement. The apparatus for conducting the test consists of small split cylinder of spring brass or other suitable metal of 0.
On either side of the split mould are attached to indicators with pointed ends, the distance from these ends to the center of the cylinder being mm. The mould shall be kept in good condition with the jaws not more than 50mm apart. COMMENTS: It is a very important test to assure the quality of cement since an unsound cement produces cracks, distortion and disintegration, ultimately leading to failure.
Fine grinding of the raw material and clinker helps to produce a sound cement. By grinding fine the raw materials, it is possible to produce a homogeneous mixture before burning where the lime is uniformly distributed. The coarse grains of cement may imprison minute particles of uncombined lime which do not hydrate. These lime particles on hydration produce disintegration. THEORY: The standard consistency of a cement paste is defined as that consistency which will permit the vicat plunger to penetrate to a point 33 to 35 mm from the top of the vicat mould.
For finding out initial setting time, final setting time, soundness of cement and compressive strength of cement, it is necessary to fix the quantity of water to be mixed in cement in each case. 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. The mould may slightly be shaken to expel the air.
In filling the mould the operator hands and the blade of the gauging trowel shall alone be used.
For each repetition of the experiment fresh cement is to be taken. COMMENTS: The water requirement for various tests of cement depends on the normal consistency of the cement, which itself depends upon the compound composition and fineness of the cement.
THEORY: In actual construction dealing with cement, mortar or concrete, certain time is required for mixing, transporting and placing. During this time cement paste, mortar, or concrete should be in plastic condition.
The time interval for which the cement products remain in plastic condition is known as the setting time. Initial setting time is regarded as the time elapsed between the moments that the water is added to the cement to the time that the paste starts losing its plasticity.
The final setting time is the time elapsed between the moment the water is added to the cement, and the time when the paste has completely lost its plasticity and has attained sufficient firmness to resist certain pressure.
The former defines the limit of handling and the latter defines the beginning of development of mechanical strength. The constituents and fineness of cement is maintained in such a way that the concrete remains in plastic condition for certain minimum time. Once the concrete is placed in the final position, compacted and finished it should lose its plasticity in the earliest possible time so that it is least vulnerable to damages from external destructive agencies. This time should not be more than 10 hours which is referred to as final setting time.
Initial setting time should not be less than 30 minutes.
The cement block thus prepared in the mould is the test block. Determination of initial setting time: 1 Place the test blocks confined in the mould and rests it on the non-porous plate, under the rod bearing initial setting needle, lower the needle gently in contact with the surface of the test block and quickly release, allowing it to penetrate into the test block. Determination of final setting time: 1 Replace the needle of the Vicat apparatus by the needle with an annular attachment.
All the apparatus shall be free from vibration during the test. Care shall be taken to keep the needle straight. COMMENTS: The factors influencing the setting properties of cement are its composition, the percentage of retardant, degree of calcination, fineness of grinding, aeration subsequent to grinding clinker, percentage of water used to make cement paste, the temperature of the mixing water, cement and the atmosphere where the cement paste is placed, and the amount of manipulation the paste receives.
Standard Sand: The standard sand to be used in the test shall conform to IS: or sand passing percent through 2 mm sieve and retained percent on 90 micron IS sieve. THEORY: The compressive strength of cement mortars is determined in order to verify whether the cement conforms to IS specifications and whether it will be able to develop the required compressive strength of concrete.
Strength test are not done on neat cement paste because of difficulties of excessive shrinkage and subsequent cracking of neat cement. Strength of cement is indirectly found on cement — sand mortar in specific proportion. The average compressive strength of at least three mortar cubes area of the face 50 cm2 composed of one part of cement and three parts of standard stand should satisfy IS code specifications.
The cubes are prepared for this purpose. Testing: 1 Take the cube out of water at the end of 3 days with dry cloth.
Measure the dimensions of the surface in which the load is to be applied. For 3 days strength: Sl. For 28 days strength: Sl. COMMENTS: In addition to the effect of composition, the strength of cement is greatly influenced by the degree of burning, the fineness of grinding, and the aeration it receives subsequent to final grinding. Under-burnt cement is likely to be deficient in strength. Compressive strength is the basic data required for mix design.
By this test, the quality and the quantity of concrete can be controlled and the degree of adulteration can be checked.
THEORY: The specific gravity of an aggregate is generally required for calculations in connection with cement concrete design work for determination of moisture content and for the calculations of volume yield of concrete.
The specific gravity also gives information on the quality and properties of aggregate. The specific gravity of an aggregate is considered to be a measure of strength of quality of the material. Stones having low specific gravity are generally weaker than those with higher specific gravity values. The bulk density of an aggregate is used for judging its quality by comparison with normal density for that type of aggregate. It is required for converting proportions by weight into proportions by volume and is used in calculating the percentage of voices in the aggregate.
Find its weight W3.
Find its weight W4 6 Repeat the same process for another trail by taking the aggregate up to the full of the container and by filling the water up to same point. Description Trial 1 Trial 2 No. Weight of empty container W1 2. Weight of container with material W2 3. Take ml of dry sand V1 ml in clean measuring jar of ml capacity. Add a measured quantity of ml clean water to the above sample V2 ml i. Shake the jar thoroughly till all air bubbles are expelled.
Moisture forms a film around each particle and this film of moisture exerts surface tension which keeps the neighbouring particles away from it. Therefore, when no point contact is possible between the particles, this causes bulking of sand.
Thus increase in volume of sand due to presence of moisture is known as bulking of sand. When more water is added sand particles get submerged and volume again becomes equal to dry volume of sand. Fine sands show greater percentage of bulking than coarse sands with equal percentage of moisture. The points on the graph should be linked as a smooth curve. Then from the graph, maximum percentage of bulking and the corresponding moisture content is determined.
Gauging trowel. Prepare a paste of grams of cement with 0. The time of gauging in any case shall not be less than 3 minutes not more than 5 minutes and the gauging shall be completed before any sign of setting occurs. Count the time of gauging from the time of adding water to the dry cement until commencing to fill the mould. Fill the Vicatts mould with this paste making it level with the top of the mould. Slightly shake the mould to expel the air.
In filling the mould the operator hands and the blade the gauging trowel shall only be used. Immediately place the test block with the non-porous resting plate, under the rod bearing the initial setting needle. Lower the needle and quickly release allowing it to penetrate in to the mould. In the beginning the needle will completely pierce the mould 4. Replace the needle of the Vicatts apparatus by the needle with an annular ring. Lower the needle and quickly release.
Repeat the process until the annular ring makes an impression on the mould. Record the period elapsed between the time of adding water to the cement to the time when the annular ring fails to make the impression on the mould as the final setting time. The time of gauging in any case shall not be less than 3 minutes not more than 5minutes.
The mixing of cement should be done in non-porous glass plate. The plunger needle should be clean every time before its penetration in the cement paste. The mixing time including placing the cement in the mould shall not exceed 4 minutes. Vicatts apparatus should be free from vibration during the penetration. Coarse aggregate is the broken stone used in concrete. The coarse aggregate unless mixed with fine aggregate serves no purpose in cement works. The size of fine aggregate is limited to a maximum of 4.
Fineness modulus is only a numerical index of fineness, giving some idea of the mean size of the particle s in the entire body of the aggregate. To a certain extent it is a method of standardization of the grading of the aggregate.
It is obtained by adding the percentage weight of material retained in each of the standard sieves and dividing it by Certain limits of fineness modulus for fine coarse aggregates are given in the table below and a sample under test should satisfy these results so that the aggregate may give good workability under economical conditions.
If the test aggregate gives higher fineness modulus the mix will be harsh and if on the other hand gives a lower fineness modulus it gives uneconomical mix. Following sieves are used I for fine aggregate- 4. Take one kg of sand from the laboratory sample. Arrange the sieves in order of IS sieves nos 4. Keep the sample in the top sieve no 4. Carry out the sieving in the set of sieves for not less than 10 minutes.
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Find the weight of sample retained in each sieve. Tabulate the values in given tabular column. Take one kg of coarse aggregate 2. Arrange the sieves one over the other in relation to their size of opening mm, 80mm, 40mm, 20mm, 10mm, and 4.
Carry out the sieving for the specified time 4. Find the weight of aggregate retained on each sieve taken in order and tabulate in table.
Apparatus: Slump cone, tamping rod, metallic sheet. Theory- The slump test result is a measure of the behavior of a compacted inverted cone of concrete under the action of gravity.
It measures the consistency or the wetness of concrete.
mm mm For Fine Fraction
This test is performed to check the consistency of freshly made concrete. Consistency is a term very closely related to workability. It is a term which describes the state of fresh concrete.
The internal surface of the mould is thoroughly cleaned and freed from superfluous moisture and adherence of any old set concrete before commencing the test. The mould is placed on a smooth, horizontal rigid and non absorbent surface. The mould is then filled in four layers each approximately of the height of the mould.
Each layer is tamped 25 times rod taking care to distribute the strokes evenly over the cross section. After the top layer has been rodded, the concrete is struck off level with a trowel and tamping rod. The mould is removed from the concrete immediately by raising it slowly and carefully in a vertical direction. This allows the concrete to subside.
This subside is referred as slump of concrete. The difference in level between the height of the mould and that of the highest point of the subsided concrete is measured.
This difference in height in mm is taken as slump of concrete. The pattern of slump indicates the characteristics of concrete in addition to the slump value. If the concrete slumps evenly it is called true slump. If one half of the cone slides down, it is called shear slump. In case of a shear slump, the slump value is measured as the difference in height between the height of the mould and the average value of the subsidence. Shear slump also indicates that the concrete is non-cohesive and shows the characteristic of segregation.
Nowadays, this test is commonly replaced by the Slump Test to determine the workability of the concrete. The sample of concrete to be tested is placed in the upper hopper up to the brim. The trap-door is opened so that the concrete falls into the lower hopper. After the top layer has been rodded, the concrete is struck off level with a trowel and tamping rod.
The mould is removed from the concrete immediately by raising it slowly and carefully in a vertical direction. This allows the concrete to subside. This subside is referred as slump of concrete. The difference in level between the height of the mould and that of the highest point of the subsided concrete is measured. This difference in height in mm is taken as slump of concrete. The pattern of slump indicates the characteristics of concrete in addition to the slump value.
If the concrete slumps evenly it is called true slump. If one half of the cone slides down, it is called shear slump. In case of a shear slump, the slump value is measured as the difference in height between the height of the mould and the average value of the subsidence. Shear slump also indicates that the concrete is non-cohesive and shows the characteristic of segregation.
Nowadays, this test is commonly replaced by the Slump Test to determine the workability of the concrete. The sample of concrete to be tested is placed in the upper hopper up to the brim. The trap-door is opened so that the concrete falls into the lower hopper.
Then the trap-door of the lower hopper is opened and the concrete is allowed to fall in to the cylinder. In the case of a dry-mix, it is likely that the concrete may not fall on opening the trap-door 3. In such a case, a slight poking by a rod may be required to set the concrete in motion.
The excess concrete remaining above the top level of the cylinder is then cut off with the help of plane blades.
The outside of the cylinder is wiped clean. The concrete is filled up exactly up to the top level of the cylinder. It is weighed to the nearest 10 grams. This weight is known as weight of partially compacted concrete 6.
The cylinder is emptied and then refilled with the concrete from the same sample in layers approximately 5cm deep.
The layers are heavily rammed or preferably vibrated so as to obtain full compaction. The top surface of the fully compacted concrete is then carefully struck off level with the top of the cylinder and weighed to the nearest 10 gm.
Apparatus required: Flow table test apparatus Procedure. The apparatus consists of flow table about 76cm. A mould made from smooth metal casing in the form of a frustum of a cone is used with the following internal dimensions. The base is 25cm. Theory- The flow table test or flow test is a method to determine the consistence of fresh concrete. Application When fresh concrete is delivered to a site by a truck mixer it is sometimes necessary to check its consistence before pouring it into formwork.
If the consistence is not correct, the concrete will not have the desired qualities once it has set, particularly the desired strength. If the concrete is too pasty, it may result in cavities within the concrete which leads to corrosion of the rebar, eventually leading to the formation of cracks. The table top is cleaned of all gritty material and is wetted.
The mould is kept on the center of the table, firmly held and is filled in two layers. Each layer is rodded 25 times with a tamping rod 1. After the top layer is rodded evenly the excess of concrete which has overflowed the mould is removed.
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The mould if lifted vertically upward and the concrete stands on its own without support. The table is then raised and dropped The diameter of the spread concrete is measured in about 6 directions to the nearest 5mm and the average spread is noted.
The value could range anything from 0 to per cent. A close look at the pattern of spread of concrete can also give a good indication of the characteristics of concrete such as tendency for segregation. Apparatus-Compression testing machine, Cubes of 15 cm size Mix. Theory- Out of many test applied to the concrete, this is the utmost important which gives an idea about all the characteristics of concrete.
By this single test one judge that whether Concreting has been done properly or not. For cube test two types of specimens either cubes of 15 cm X 15 cm X 15 cm or 10cm X 10 cm x 10 cm depending upon the size of aggregate are used. For most of the works cubical moulds of size 15 cm x 15cm x 15 cm are commonly used.
This concrete is poured in the mould and tempered properly so as not to have any voids. After 24 hours these moulds are removed and test specimens are put in water for curing.
The top surface of this specimen should be made even and smooth. This is done by putting cement paste and spreading smoothly on whole area of specimen.
These specimens are tested by compression testing machine after 7 days curing or 28 days curing. Load at the failure divided by area of specimen gives the compressive strength of concrete. Mixing- Mix the concrete either by hand or in a laboratory batch mixer A. Hand Mixing1. Mix the cement and fine aggregate on a water tight none-absorbent platform until the mixture is thoroughly blended and is of uniform color. Add the coarse aggregate and mix with cement and fine aggregate until the coarse aggregate is uniformly distributed throughout the batch.
Add water and mix it until the concrete appears to be homogeneous and of the desired consistency B. Clean the mounds and apply oil. Fill the concrete in the molds in layers approximately 5cm thick. Level the top surface and smoothen it with a trowel. Curing- The test specimens are stored in moist air for 24 hours and after this period the specimens are marked and removed from the molds and kept submerged in clear fresh water until taken out prior to test.Procedure: 1. The outside of the cylinder is wiped clean.
These specimens are tested by compression testing machine after 7 days curing or 28 days curing. Screw on the cap upto the mark. Add a measured quantity of ml clean water to the above sample V2 ml i.
Cover the mould with another piece of glass sheet, place a small weight on this covering glass sheet and immediately submerge the whole assembly in water at a temperature of 27 2oC and keep it there for 24hrs.
The bottom diameter 20 cms, and height 30cms.
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