Summer Internship Report 18, May 2016 to 21, June 2016

Submitted by:-Deepak KumarRoll No: 13010110444th year undergraduate student,Department of Civil Engineering, DIT University, Dehradun

1. ACKNOWLEDEMENT

I am very thankful to Delhi Metro Rail Corporation Ltd. for having given me the opportunity to undertake my summer internship/training at their prestigious project Design and construction of tunnel & underground metro station from Janakpuri West to Botanical Garden (CC-32 and CC-34).

It was a very good learning experience for me to have worked at this site. I would like to convey my heartiest thanks to Mr. Pramod Ahuja (CPM-5) who heartily welcomed me for the training. I would also like to thanks Mr. Balwant Kumar (PM-5A), Mr. Manoj Bajpyee (PM-5B), Mr. Rupesh Srivastava (SE Civil) and Mr. Pankaj Kumar (JE) who guided and encouraged me all through the summer training.

Last but not the least; I would like to thanks all the staff at DMRC for being so helpful during this summer training.

1

2. PREFACEProject gives an opportunity to implement the principles and knowledge practically. The experience that one gets is wonderful because one study in books is different from what one face in the field.

A project helps a student in getting acquainted with the manner in which his knowledge is being practically used and this is normally different from what one has learnt from books. Hence, when one switches from the process of learning to that of implementation his knowledge, he finds an abrupt change. This is exactly why industrial training during the B.Tech. Curriculum becomes all the more important.

Imagine large drives used in site, they are really effective and helpful. Also imagine of we could control different machines and equipment at sites or industry by using another device. My training includes these basic some important engineering needs in an industry.

2

3. INTRODUCTION ABOUT THE ORGANIZATIONThe Delhi Metro Rail Corporation Ltd. Abbreviated to DMRC, is a centre-state public sector company that operates the Delhi metro. The DMRC was founded on 3 May 1995 at New Delhi, India by E. Sreedharan, serving as the first managing director E. Sreedharan handed over charge as MD of DMRC to Magnu Singh on 31 December 2011.

The DMRC is also involved in the planning and implementation of metro rail, mono rail and high speed rail project in India and abroad. DMRC has served as the project consultant and has prepared detailed project report (DPR) for every metro and mono rail project in India, except the Kolkata Metro and Chennai MRTS.

The DMRC has been certified by the United Nations as the first metro rail and rail-based system in the world to get “carbon credits for reducing greenhouse gas emissions” and helping in reducing pollution level in the city.

3

4. PROJECT DETAILS4.1. Site Location

Fig: Site location

I am very thankful to DMRC for given me the opportunity to learn the practical aspect of civil engineering work on their prestige project. During first week of my training I was exposed to CC32 (UG-3) which is located next to Indira Gandhi domestic airport. And after that I was allowed to go CC34 (UG-5) which is located near existing Janakpuri West metro station in order to complete my industrial training.

4

4.2. Site map of CC32

Fig: Master plan of CC32(UG-3)

Fig: detail plan of cross over-1 cc32

4.3. Site Map of CC34

5

Fig: Plan of cross-over 2 CC34

Fig: Plan of undercroft level

4.4. About the Project

Key details about CC34(UG-5)

Client DMRCLocation DelhiContract Type Design and construction basis.Contractor HCC-Samsung JV (Share 50 : 50) and HCC is leaderCompletion period 46 months (18 Feb. 2013 ~ 01 Dec. 2016)Contract Value 865.98 Cr. (A = 812.04, B = 41.18, C = 12.76)

6

Scope of work Design and construction of Twin tunnel between ch. 830.912 and 4591.63 by shield

TBM. (4.363 KM Each) 0.113 km and 0.158KM long Crossovers on either side of

Janakpuri station by C/C Method. U/G Stations at Janakpuri West, Dabri Mor and

Dashrathpuri including architectural finishing of stations. Interchange facilities between old and new Metro station

at Janakpuri.

7

PPE

5. SAFETY INDUCTIONIn safety induction safety engineer told us about the use of safety equipment and PPE (Personal Protective Equipment) at construction site.

5.1. PPE(Personal Protective Equipment)

Fig: safety Glasses

Fig: Safety Gloves Fig: Safety shoes

Fig: Nose Mask

Fig: Ear Plug

Fig: safety helmet

8

5.2.Colour Code for Safety HelmetsSafety Helmet colour Person to Use

White All DMRC staff

Grey All Designer, Architect, Consultants etc

Violet Main Contractors(Engineers/Supervisors)

Blue All Sub -Contractors (Engineers/Supervisor)

Red Electricians ( Both Contractor & Sub contractorGreen Safety Professionals ( Both Contractor& Sub contractorOrange Security Guards/ Traffic MarshalsYellow All WorkmenWhite(with visitor sticker) Visitors

9

6. SURVEYING DURING WORKSite surveys are detailed studies carried out to supplement and verify site information provided by the client. During execution the surveying is important to identify the location, defining the level. Moreover during execution, project of any magnitude is constructed along the lines and point established by surveying.

1. Auto Level2. Total Station

6.1 Auto Level

Modified version of dumpy level is known as auto level which is a levelling instrument, or auto level is an optical instrument used to establish or verify points in the same horizontal plane. It is used in surveying and building with a vertical staff to measure height differences and to transfer, measure and set heights.

Apparatus used Fig: Auto Level

Tripod stand, auto level, shaft, meassuring tap

Procedure

1. Set the tripod in level(3 legs sre level and equal).2. Set auro level on tripod stand.3. Set bubble in centre.4. Read the reading in cross hair level.

Observation Table for Calculation

Station B.S. I.S. F.S. H.L. R.L.

Where B.S- Back SightI.S.- Intermediate SightF.S.- Fore SightH.I.- Height of Instrument R.L.- Reduced Level Fig: showing number of station

Formulae:-

10

H.I = R.L + B.SF.S = H.I – R.L of staff in fore direction

6.2 Total StationA Total Station is a modern surveying instrument that integrates an electronic theodolite with an electronic distance meter. The total station is an electronic theodolite (transit) integrated with an electronic distance meter (EDM) to read slope distance from the instrument to a particular point.

Function of total station:-1. Angle Measurement2. Distance Measurement 3. Coordinate Measurement 4. Data Processing

11

12

7. TUNNEL OVERVIEW

FIG: Constructed Tunnel

KEY POINTS ABOUT TUNNEL:-

Tunnels are constructed with the help of TBM (tunnel Boring Machine)

The type of tunnel is “twin tunnel”. Inner diameter of tunnel is 5.8m Outer diameter is 6.5m There are 6 segment key in one ring of thickness

275mm and length 1.4m A cross passage is provided after every 200 rings for

emergency exit. The lowermost of the tunnel is 20m below the ground

surface. Fig: tunnel location below GS

13

8. TBM (Tunnel Boring Machine)A tunnel Boring machine also known as “mole“, is a machine used to excavate tunnels with a circular cross section through a variety of soil and rock strata. They can bore through anything from hard rock to sand. Tunnel diameter can range from a meter (done with micro-TBM) to 19.25 meter to date.

Fig: TBM (Tunnel Boring Machine)

Tunnel boring machine are used as an alternative to drilling and blasting methods in rock and conventional “hand mining “in soil. TBM have the advantages of limiting the disturbance to the surrounding ground and produced a smooth tunnel wall. The major disadvantage is the upfront cost. TBMs are expensive to construct, and can be difficult to transport. However, as modern tunnels become longer, the cost of tunnel boring machines versus drill and blast is actually less.

14

9. WATER PROOFING Roof slab waterproofing using Master Seal Roof 3500

This waterproofing system is multi-layered and comprise of a series of substrate sealers, primers and waterproofing membrane.

Fig: Masterplan for waterproof

s.no Description Product Consumption Packing1 Primer Master Seal P2525 0.40 Kg/m2 Master Seal

P2525 Pack: 3Kg2 Sand

BroadcastingOven Dried Silica Sand (.3-.8mm) Master top SRA No3

0.8-1.0 kg/ m2 Pack: 25 kg

3 Waterproofing Membrane

Masterseal M800-Part A, GreyMasterSeal M800- Part B, un-pigmented

2.65Kg/m2 Part A: 210 Kg Part B: 220 Kg

15

The seamless, Monolithic waterproofing will obtain from the CONIROOF system in several application stages:

9.1. Surface preparation Uneven concrete should be leveled to produce a smooth, flat surface. For heavy wear situation a repair mortar Master Emaco S 488 will be used and bug holes will be repaired by using epoxy putty Master Brace 2200.Finally ensure the surface is dust free by using an industrial vacuum cleaner.

Fig: cleaning of surface

10.

16

11.

11.

11.

11.

11.

11.

12.

Fig: surface grindig Fig: surface dressing

9.2. Pre-Application conditionThe moisture level on the substrate will be ensured below 4% at the time of application of MasterSeal Roof system and the application will be avoided if the humidity is high or if it rains. Application of the primer should be avoided if the temperature will fall below 10 C and if incase of high temperature above 30 C, application will be done in falling temperature.

17

Fig: Drying of the surface Fig: moisture checking

9.3. Preparation for Primer coat Epoxy primer Master Seal P 2525 should be applied with hand brush at the consumption rate mention in the table to ensure that the primer has

Fig: primer coat

got absorbed properly by pores or micro pores of the concrete surface and it applied homogeneously by the complete surface.

Graded aggregate will be sprinkled immediately after applying primer to the surface properly.

9.4. Spraying of MasterSeal M 800 membrane A solvent free, two components, SPRAY applied waterproofing membrane will be sprayed by special, two components spray equipment. Required thickness of membrane minimum 2.5 mm will be checked with the help of thickness gauge.

18

Fig: spraying of Master Seal M800 membrane

9.5Test Thickness of the membrane is checked And the roof is checked for any leakage by ponding test

Fig: ponding test9.5. Treatment of construction joint

1. Cutting grooves of 25X25mm at construction joint of roof slab/wall with the help of suitable mechanical equipment.

2. All the loose particles, dust etc will be cleaned with the help of wire brush and air blower.

19

3. Removal of any type of contamination will be ensured.4. Groove will be pre-saturated with water before application.5. MasterSeal 502 will be mixed with water as recommended in product technical data

sheet.6. Mixed material will be poured in the groove with proper compaction.7. MasterSeal M800 membrane will be sprayed as per the method statement.

Fig: construction joint

20

10.METHOD FOR REINFORCEMENT WORK1. All reinforcement shall be placed above the ground by using PVC

cover block or concrete blocks.2. For reinforcement, care shall be taken to

protect the reinforcement from exposure to saline atmosphere during storage, fabrication and use.

3. Against requirement from site, bars shall be cut and bent to shape and dimension as shown in bar bending schedule based on Good For Construction (GFC) drawings. Fig: PVC cover block

4. Reinforcement shall be tied as per the latest GFC drawing and any

Fig: reinforcement of slabextra bars provided at site shall be recorded in the pour card/ lap register.

5. Unusable cut rods and scrap reinforcement shall be properly placed at yard.

11.BAR BENDING SCHEDULE:1. Prepare bar bending schedule based on the latest GFC drawings and

to be submitted to Engineer for review

21

2. Bar bending schedule shall clearly specify the following:a. Bar diameter,b. Numbers,c. Cut-lengths,d. Shapes.

3. Bar bending schedule shall take into account the following field/ design requirement.

a. Desirable lap locations and staggering of laps.b. Lap lengths.c. Development length/ Anchorage length.

s.no

Member name

Bar mark no.

Sketch

Dia of bar

Cut Length

Bending dimension

No. of sets

No. of bar per set

Total no. of bar

Total cut length

Unit weight

Total weight

mm

m mm m Kg/m KG

12.OVERLAPPING OF BARSStaggering of reinforcement shall be carried out in such a manner that not more than 50% lapping be provided at any section.

22

Fig: overlapping of bars

13.REBARINGRebaring is the method of insertion of steel bars when:-

1. There is change in design or there is some extension of present structure.

2. When steel rod as per has been not installed and to install the same rebaring

Fig: cleaning of holes Fig: rebaring work

23

Mostly HILTI chemical are used for rebaring

Steps involved:-

1. Drilling in the existing structure as per drawing 2. Cleaning of holes by ELE blower3. Filling of chemical in well cleaned holes 4. Then inserting bars slowly inside the holes

24

14.CUTTING, BENDING & PLACING:1. All reinforcement shall be free from loose mill scales, loose rust and coats of paints,

oil, mud or any other substances which may destroy or reduce bond. Use wire brush to clean the reinforcement.

2. Cutting and bending shall conform to the details given in the approved bar bending schedule.

a. Cutting of Rebar by heat is not permitted, only by grinding or shearing is permitted.

b. No heating is allowed to facilitate bending of rebar

25

Fig: cutting of steel bars3. Place the reinforcement as per GFC drawings

ensuring the following aspects properly.a. Type & size of bar,b. Number of bars,c. Location and lengths of laps,

splices.d. Curtailment of bars.e. In two way reinforcement, check

the direction of reinforcement in various layers.

f. Adequate number of chairs, spacer bars and cover blocks.g. Size of cover blocks.h. All the bars shall be tied with double fold 18g soft GI annealed binding wire.

4. Reinforcement may be placed with in the following tolerance whenever required:a) For effective depth 200mm or less ±10mm.b) For effective depth more than 200mm ±15mm.c) The cover shall in no case be reduced by more than one third of the specified cover or 0 /+ 10mm.d) The cover should suit various cover requirements as per Drawing Notes.

5. The sequence of reinforcement shall be correlated with fixing of inserts, sleeves, conduits, anchors and formworks.

6. In walls, place accurately bent spacer bars wired to vertical or horizontal bars between successive rows.

7. No steel parts of spacers sure allowed inside the concrete cover. Spacer

8.b

Fig: placing of steel reinforcement of the slab

26

locks made from cement, sand and small aggregate shall match the mix proportion of the surrounding concrete. Alternatively PVC cover blocks of approved make can be used.

9. Spacers, cover blocks should be of concrete of same strength or PVC10. Spacers, chairs and other supports detailed on drawings, together with such other

supports as may be necessary, should be used to maintain the specified nominal cover to the steel reinforcement.

11. Spacers or chairs should be placed at a maximum spacing of 1.0 mtr and closer spacing may sometimes be necessary.

12. All reinforcement shall be placed and maintained in the positions shown in the drawing by providing proper cover blocks, spacers, Supporting bars.

13. Rough handling, shock loading (Prior to embedment) and the dropping of Reinforcement from a height should be avoided. Reinforcement should be secured against displacement.

27

15.METHOD FOR CONCRETING15.1. Placing of concrete

1. Concrete pump with pipeline is used for conveyance of concrete to the pouring area.2. Concrete for the slab is placed in approx. 400mm-450mm thick layers each. Each

layer is compacted before the next layer is placed.3. Concrete is carefully worked around all reinforcement and embedded fixtures and

corner of formwork.4. The top surface of the concrete is leveled with aluminum box section of 3m long

followed by steel trowel to produce the required surface finish.5. Concrete placing is uninterrupted until placing of a section as defined by construction

joints is completed.6. The concrete at the surface of cold joints is cleaned with a high pressure air water jet

before the concrete achieves a primary set to provide an

Fig: placing of concrete over reinforcement for roof slab

irregular clean surface free from laitance. Prior to restarting concreting, the surface will

be wetted.

7. Maximum free fall of concrete will be limited to 1.5m.8. The temperature of the concrete should not exceed the limiting temperature

mentioned in the plan.

28

15.2. Compaction of concrete

Concrete is compacted during placing by immersion vibrators. An immersion vibrator is operated in a near vertical position, and it penetrate the full length of the layer of concrete placed and just into the layer below to stich in between. Vibration will be applied continuously until the expulsion of air has practically ceased. The vibrators will be withdrawn slowly to avoid the formation of voids. Fig: positions of immersion vibratorsDuring the compaction care will be taken to avoid the displacement of reinforcement, formwork, pre-fixed pipes, etc.A minimum of one standby vibrator will be provided during concreting.

Fig: compaction of concrete

15.3. Curing of concreteThe following procedure will be followed in curing the slab concrete.

15.3.1 Horizontal Surface a. As part of the slab is concreted up to final level including final surface finishing, the

finished surface will be covered with hessian cloth.

29

b. The hessian will be kept permanently damp by periodical spray of water through water hoses or by ponding arrangement in lieu of hessian cloth. The curing will be continued for 14 days.

Fig: Horizontal Surface Curing

15.3.2 Vertical Surface

The curing of vertical surface of slab, walls or columns will be continued covered with hessian cloth and kept damp by periodical spray of water for 10 days

Fig: Vertical Surface Curing

30

16.METHOD FOR FORMWORK16.1. Pre Check

1. Check if the shutters are properly cleaned by removing the concrete/ mortar and protruding nails.

2. Formwork shall be made to the exact dimensions within the permissible tolerances as mentioned below.

3. Required thickness and quality of plywood conforming to IS 6461 shall be used to meet the requirements of design and surface finish.

4. For beam bottom & sides, proper size of timber at required spacing shall be provided to take the design loads/ pressure considering sleeves, conduit anchors & inserts.

16.2. Erection of formwork1. Sufficiently rigid and tight to prevent the loss of grout or mortar from the concrete.2. Capable of providing concrete of the correct shape and surface finish within the

specified tolerance limits.

3. Soffits forms capable of imparting a camber if required.

4. .The formwork may be of timber, plywood, steel, plastic or concrete depending upon

the type of finish specified.

5. Erect staging/shuttering as per drawing/sketches in such a way that de-shuttering can

be done easily including provision for re-propping, if planned.

6. Check the location, line, level, plumb and dimensions of the formwork to ensure that

the deviations are within the permissible limits.

7. Provide bracing at proper places & intervals as specified by the manufacturer or as per

formwork scheme to take care of lateral loads.

8. Apply mould oil/other coatings as release agents before reinforcement steel is placed.

9. Wire ties passing through beams, columns and walls shall not be allowed .In their

place bolts passing through sleeves shall be used .For liquid retaining structures,

sleeves shall not be provided for through bolts.

10. Check all the shutters are properly aligned and fixed firmly with required lateral

supports and ties.

11. Check all the spanning members have proper bearing at the supports.

12.Wedges or jacks shall be secured in position after the final check of alignment.13. Forms shall be thoroughly cleaned of all dirt, mortar and other matters such as metals,

blocks, saw dust and foreign materials before concreting if required through clean-out

openings.

14. Check all the gaps/openings are properly closed to avoid leakages.

31

15. Check all the inserts/embedment and openings are exactly placed as per the drawings.

16. In case of leakages, bulging and sagging immediate actions shall be taken by

tightening wedges or adjusting by jacks which must be done before the concrete takes

its initial set

.

16.3. Removal of Forms1. Formwork components shall not be dropped but shall be lowered without damage to

the components and structures. All the removed formwork materials shall be

thoroughly scarped, cleaned immediately and stacked properly for reuse.

2. 'All forms shall be removed after the minimum period stipulated mentioned below

without damage to the concrete including removal without shock as per IS 456

32

17. METHOD FOR BACKFILLING17.1 Procedure for bottom-up construction1. The backfill material used shell be suitable earth complying with the required

specification,2. Timber lagging if any between soldier piles shall be removed for 1.5 m at a time above

the excavated level and backfilling with soil of @300mm compacted thickness layer is done initially.

3. Compaction of each layer is done using plate compactor and whereas space constraint is there manual tamping will be done.

4. The soil is compacted till 95% compaction is achieved for each layer.5. Dumping, spreading and compaction of soil is continued in layers of @300mm until the

level of working height for laying water proofing membrane below the roof slab top level, is reached.

6. Waterproofing membrane is sprayed over the roof slab.7. Once roof slab top level is reached on one side, soil is dumped above the roof slab to be

spread on the other side of tunnel box section.

Fig: backfilling8. Steps 1 to 5 are repeated for the other side, and space between tunnels boxes, wherever

applicable.9. Once roof slab top level is reached more soil is dumped over the roof slab. Soil is

backfilled and spread in layers of 200mm .10. Compaction of soil layers is done above roof slab top level using Tandem vibratory

walk behind rollers, plate compactor.11. Dumping, spreading and compaction of soil is done in layers of @200mm until the strut

level above is reached.12. The procedure of dumping, spreading and compacting the soil in layer of 200mm are

repeated until the next strut level above/ ground level is reached.

33

13. Compaction test shall be conducted in 1200cum of each layer

17.2. Procedure for Top-Down construction

1. The backfill material used shell be suitable earth complying with the required specification

2. Waterproofing membrane is sprayed over the roof slab.3. Dumping, spreading and compaction of soil are done in layer of @ 300 mm compacted

thicknesses until the desired compaction level is achieved.4. Compaction of soil layers is done above roof slab top level using Tandem vibratory

walk behind rollers, plate compactor.5. The soil is compacted till 95% compaction is achieved for each layer and testing

requirement shall be as per criteria specified.

Fig: compaction of backfill by roller

17.3. Procedure for areas having Utilities1. The backfill material used shall be suitable earth / fine sand complying with the required

specification.2. Compaction of soil layer is done using rammer, plate compactor and manual compaction

will be done. Special care is taken during the the compaction such that utilities are not damaged during the compaction.

3. Dumping, spreading and compaction of soil are done in layer of @ 200 mm compacted thicknesses until the desired compaction level is achieved.

4. The soil is compacted till 95% compaction is achieved for each layer and testing requirement shall be as per criteria specified.

34

18. BLOCK WORKS 18.1. Materials

The following materials are required :-

Pre cast solid cement concrete blocks (LxWxH).400x200x200mm/ 400x200150mm/ 400x200x140mm/ 400x200x100mm as mentioned in approved drawing.

Mortar sand Cement(53grade OPC) Wire mesh Steel bars

18.2. Work Procedure

Handling of pre cast solid cement concrete block Setting out the wall locations Production of mortar at site The proportion of cement and sand in the mortar shall be cement : sand = 1:4 (without

any additives) Kinker construction for cavity wall Laying of blocks

all the blocks shall be moist nearly half an hour and again immediately befor laying.1. Stand and set lumbers with a straight edges along the vertical line of wall face to

vertical alignment of the work.2. Then stretch a string line indicting the top level of the starting course 3. Top of concrete slab, from which block are laying up, should be kept clean and

wet.4. Lay the blocks for the course with a uniform thickness of horizontal joint.5. Standard length of block is 400mm and in case a cut unit is required to make up

the course, place that unit made of standard unit at least one block away from the concrete column, quoins of the wall or service openings including doors and windows.

6. After finishing the course,carry out jointing with the steel trowel to strike off joints slightly lower than the block face in case plastering or rendering are not required at a later stage. However, only where plastering is required, take out joints to a depth of between 10mm to 15mm as the works proceeds, to give an adequate key to plastering.

7. Repeat sequence for the next course.

35

36

Fig: showing mesh wire and steel bar Fig: block work in front of retaining wall

37

19. QUALITY ASSURANCE & QUALITY CONTROL

Quality is the key component which propels performance and defines leadership traits. At Delhi Metro Rail Corporation Ltd., Quality Standards have been internalized and documented in Quality Assurance manuals. DMRC recognizes the crucial significance of the human element in ensuring quality. Structured training programmes ensure that every employee is conscious of his/her role and responsibility in extending DMRC Construction’s tradition of leadership through quality. Relevant procedures established clearly specify the criteria and methods for effective operation, control and necessary resources and information to support the operation and monitoring of these processes.

19.1 TESTS ON CEMENT19.1.1 CONSISTENCYAIMTo determine the quantity of water required to produce a cement paste of standard consistency as per IS: 4031 (Part 4) - 1988.PRINCIPLEThe standard consistency of a cement paste is defined as that consistency which will permit the Vicat plunger to penetrate to a point 5 to 7mm from the bottom of the Vicat mould.APPARATUSVICAT APPARATUSVicat apparatus conforming to IS: 5513 - 1976 Balance, whose permissible variation at a load of 1000g should be +1.0g Gauging trowel conforming to IS: 10086 - 1982PROCEDUREi) Weigh approximately 400g of cement and mix it with a weighed quantity of water.The time of gauging should be between 3 to 5 minutes.ii) Fill the Vicat mould with paste and level it with a trowel.iii) Lower the plunger gently till it touches the cement surface.iv) Release the plunger allowing it to sink into the paste.v) Note the reading on the gauge.vi) Repeat the above procedure taking fresh samples of cement and different quantities of water until the reading on the gauge is 5 to 7mm.REPORTING OF RESULTSExpress the amount of water as a percentage of the weight of dry cement to the first place of decimal.

19.1.2. INITIAL AND FINAL SETTING TIMEAIMTo determine the initial and the final setting time of cement as per IS: 4031 (Part 5) -1988.APPARATUS

38

Vicat apparatus conforming to IS: 5513 - 1976 Balance, whose permissible variation at a load of 1000g should be +1.0g Gauging trowel conforming to IS: 10086 - 1982PROCEDUREi) Prepare a cement paste by gauging the cement with 0.85 times the water required to give a paste of standard consistency.ii) Start a stop-watch, the moment water is added to the cement.iii) Fill the Vicat mould completely with the cement paste gauged as above, the mould resting on a non-porous plate and smooth off the surface of the paste making it level with the top of the mould. The cement block thus prepared in the mould is the test block.INITIAL SETTING TIMEPlace the test block under the rod bearing the needle. Lower the needle gently in order to make contact with the surface of the cement paste and release quickly, allowing it to penetrate the test block. Repeat the procedure till the needle fails to pierce the test block to a point 5.0 ± 0.5mm measured from the bottom of the mould . The time period elapsing between the time, water is added to the cement and the time, the needle fails to pierce the test block by 5.0 ± 0.5mm measured from the bottom of the mould, is the initial setting time.FINAL SETTING TIMEReplace the above needle by the one with an annular attachment.The cement should be considered as finally set when, upon applying the needle gently to the surface of the test block, the needle makes an impression therein, while the attachment fails to do so. The period elapsing between the time, water is added to the cement and the time, the needle makes an impression on the surface of the test block, while the attachment fails to do so, is the final setting time.REPORTING OF RESULTSThe results of the initial and the final setting time should be reported to the nearest five minutes.

19.2. TESTS ON AGGREGATES

19.2.1. SIEVE ANALYSISAIMTo determine the particle size distribution of fine and coarse aggregates by sieving as per IS: 2386 (Part I) - 1963.PRINCIPLEBy passing the sample downward through a series of standard sieves, each ofdecreasing size openings, the aggregates are separated into several groups, each of which contains aggregates in a particular size range.APPARATUSA SET OF IS SIEVESi) A set of IS Sieves of sizes - 80mm, 63mm, 50mm, 40mm, 31.5mm, 25mm, 20mm, 16mm, 12.5mm, 10mm, 6.3mm, 4.75mm, 3.35mm, 2.36mm, 1.18mm, 600μm, 300μm, 150μm and 75μmii)Balance or scale with an accuracy to measure 0.1 percent of the weight of the test sample

39

PROCEDUREi) The test sample is dried to a constant weight at a temperature of 110 + 5oC and weighed.ii) The sample is sieved by using a set of IS Sieves.iii) On completion of sieving, the material on each sieve is weighed.iv) Cumulative weight passing through each sieve is calculated as a percentage of the total sample weight.v) Fineness modulus is obtained by adding cumulative percentage of aggregatesretained on each sieve and dividing the sum by 100.

REPORTING OF RESULTSThe results should be calculated and reported as:i) the cumulative percentage by weight of the total sampleii) the percentage by weight of the total sample passing through one sieve andretained on the next smaller sieve, to the nearest 0.1 percent.

19.2.2. WATER ABSORPTIONAIMTo determine the water absorption of coarse aggregates as per IS: 2386 (Part III) -1963.APPARATUSi) Wire basket - perforated, electroplated or plastic coated with wire hangers for suspending it from the balanceii) Water-tight container for suspending the basketiii)Dry soft absorbent cloth - 75cm x 45cm (2 nos.)iv)Shallow tray of minimum 650 sq.cm areav) Air-tight container of a capacity similar to the basketvi) Oven SAMPLE A sample not less than 2000g should be used.PROCEDUREi) The sample should be thoroughly washed to remove finer particles and dust,drained and then placed in the wire basket and immersed in distilled water at atemperature between 22 and 32oC.ii) After immersion, the entrapped air should be removed by lifting the basket and allowing it to drop 25 times in 25 seconds. The basket and sample should remain immersed for a period of 24 + 1⁄2 hrs. afterwards.iii) The basket and aggregates should then be removed from the water, allowed to drain for a few minutes, after which the aggregates should be gently emptied from the basket on to one of the dry clothes and gently surface-dried with the cloth, transferring it to a second dry cloth when the first would remove no further moisture.The aggregates should be spread on the second cloth and exposed to the atmosphere away from direct sunlight till it appears to be completely surface-dry. The aggregates should be weighed (Weight 'A').iv) The aggregates should then be placed in an oven at a temperature of 100 to 110oC for

24hrs. It should then be removed from the oven, cooled and weighed (Weight 'B').

REPORTING OF RESULTSWater absorption = [(A-B)/B] x 100%

40

19.3. TESTS ON CONCRETE

19.3.1 SLUMPAIMTo determine the workability of fresh concrete by slump test as per IS: 1199 - 1959.APPARATUSi) Slump coneii) Tamping rodPROCEDUREi) The internal surface of the mould is thoroughly cleaned and applied with a light coat of oil.ii) The mould is placed on a smooth, horizontal, rigid and non- absorbent surface.iii) The mould is then filled in four layers with freshly mixed concrete, eachapproximately to one-fourth of the height of the mould.iv) Each layer is tamped 25 times by the rounded end of the tamping rod (strokes are distributed evenly over the cross- section).v) After the top layer is rodded, the concrete is struck off the level with a trowel.vi) The mould is removed from the concrete immediately by raising it slowly in the vertical direction.vii)The difference in level between the height of the mould and that of the highest point of the subsided concrete is measured.viii) This difference in height in mm is the slump of the concrete.

REPORTING OF RESULTSThe slump measured should be recorded in mm of subsidence of the specimen during the test. Any slump specimen, which collapses or shears off laterally gives incorrect result and if this occurs, the test should be repeated with another sample. If, in the repeat test also, the specimen shears, the slump should be measured and the fact that the specimen sheared, should be recorded.

19.3.2. Compressive strength test/cube testOut of many test applied to the concrete, this is the utmost important which gives an idea about all the characteristics of concrete.Preparation of cube specimens MOULD The mould shall be of size 15cm X 15cm X 15cm for the maximum nominal size of aggregate not exceeding 40mm. Each mould shall be provided with base plate having a plane surface and made of non-absorbent material. Fig: Mould SAMPLE OF CONCRETE

41

Sample of concrete for the test specimen shall be taken at the mixer or in the case of ready mixed concrete from the transportation vehicle discharge or as directed by Engineer-in-charge.

SAMPLING

1. Clean the mould and apply oil.2. Fill the concrete in the mould in layer approximately

5cm thick. 3. Compact each layer with not less than 35 strokes per

layer using a tampering rod (steel bar 16mm diameter and 60cm long, bullet pointed at lower end) fig: concrete cube sample

4. Level the top surface and smoothen it with trowel

CURINGThe test specimens are then stored in moist air for 24 hours and after this the specimens are marked and removed from the molds and kept submerge in clear fresh water until taken out prior to test. Fig: curing of concrete cubes TESTING PROCEDURE

1. Remove the specimens from the water after specified time and wipe out excess water from the surface

2. Take the dimension of the specimen to the nearest 0.2m3. Clean the bearing surface of the testing machine

Fig: cube testing4. Place the specimen in the machine in such a manner that the load shall be applied to

the opposite side of the cube cast.5. Rotate the movable portion gently by hand so that it touches the top surface of the

specimen 6. Apply the load gradually without shock and continue till the specimen fail

Fig: compressive testing

7. Record the maximum load and note any unusual features in the type of failure.

Compressive strength of different grades of concrete at 7 and 28 days

42

Grade of Concrete

Minimum compressive strength N/mm2 at 7 days

Specified characteristic compressive strength (N/mm2) at 28 days

M15 10 15M20 13.5 20M25 17 25M30 20 30M35 23.5 35M40 27 40M45 30 45

19.4. IN-SITU DRY DENSITY

19.4.1 CORE CUTTER METHOD

AIMTo determine the in-situ dry density of soil by core cutter method as per IS: 2720 (Part XXIX) - 1975.APPARATUSi) Cylindrical core cutterii) Steel dolleyiii) Steel rammeriv) Balance, with an accuracy of 1gv) Straightedgevi) Square metal tray - 300mm x 300mm x 40mmvii) TrowelPROCEDUREi) The internal volume (V) of the core cutter in cc should be calculated from itsdimensions which should be measured to the nearest 0.25mm.ii) The core cutter should be weighed to the nearest gram (W1).iii) A small area, approximately 30cm square of the soil layer to be tested should be exposed and levelled. The steel dolly should be placed on top of the cutter and the latter should be rammed down vertically into the soil layer until only about 15mm of the dolly protrudes above the surface, care being taken not to rock the cutter. The cutter should then be dug out of the surrounding soil, care being taken to allow some soil to project from the lower end of the cutter. The ends of the soil core should then be trimmed flat in level with the ends of the cutter by means of the straightedge.iv) The cutter containing the soil core should be weighed to the nearest gram (W2).v) The soil core should be removed from the cutter and a representative sample should be placed in an air-tight container and its water content (w) determined.REPORTING OF RESULTSBulk density of the soil γ = (W2 −W1)/V g /ccDry density of the soil γd = [100γ/100+w] g c

20. CONCLUSION 43

From the field study report, it is evident that the construction activity is going on full swing

using all the safety norms as per ISO. It was a wonderful learning experience at Delhi Metro

Rail Corporation Ltd. for 5 weeks at CC32(UG-3) and CC34(UG-5). I gained a lot of insight

regarding several aspect of site. I was given exposure in almost all the departments at the site.

The friendly welcome from all the employees is appreciating, sharing their experience and

giving their peace of wisdom which they have gained in long journey of work. I am very

much thankful for the wonderful accommodation facility from DMRC. I hope this experience

will surely help me in my future and also in shaping my career.

44