Quality Control in Construction12.Doc

PREFACEThis workshop “ QUALITY CONTROL IN CONSTRUCTION” is primarily intended for

each and everyone – Builders, Architects, Consultants, Engineers, Site Engineers andGovernment Agencies – who are associated with construction .

CREDAI- VIZIGANARAM, felt it appropriate to highlight the importance of quality inconstruction activity.

Rapid urbanization is resulting in shrinkage of land available for housing. HenceDevelopment of multistoried constructions are taking rapid strides even in small and mediumtowns. New entrepreneurs with limited knowledge about the technical aspects of constructionare attracted. This workshop is aimed to create awareness among all concerned peopleare attracted. This workshop is aimed to create awareness among all concerned peopleinvolved in this activity and stress the importance of quality assurance in building construction.In this regard, CREDAI - VIZIGANARAM, conveys their whole hearted gratitude to1.Sri K.S Chandran2.Sri Y. Narasimha Rao3.Sri M.G Madavababu4.Sri A.R Murthy5.Sri M.Ramesh6.Sri N.Vamsi Mohan

for their technical guidance and support for bringing out this invaluable andinformative edition to all the construction fraternity.

Date:- 05-01-2001 CHAIRMANCREDAI - VIZAGANARAM1

CREDAI VIZIAGANARAM CHAPTER thank all the participants andspeakers for making this event a grand success. Also we thank Ar.Y. NarasimhaRao ( Past chairman IIA, Visakhapatnam Center) for his whole heartedguidance spearing his valuable time.

2

Dear Mr Raj,

It is very heartening that CREDAI VIZIANAGARAM hasorganized yet another program. I am sure the workshop on qualitycontrol shall benefit all the members of CREDAI and the delegateswho attend this workshop. I sent my best wishes for the success ofthe event.

3

the event.

Thanking you,With kind regards,SANTOSH RUNGTA

Message from K.Subba Raju Garu ( Chairman, CREDAI-Visakhapatnam)

4

Checking the working plan with respect to site conditions before starting the work

Level fixing relating to external drainage level in order to connect future sewage & sewerage system.

Cross check the measurements issued by the Architects/Structural Engineers w.r.t site.

For example :

INSPECTION

QUALITY CONTROL IN CONSTRUCTION

For example :Length & breadth totalling of measurements.

DewateringUp to 2' to 3' dewatering must be carried out to the nearest drain but not to the neighbour's site.

Marking for footings

This should be done accurately as per the plan.

The marking must be done only by metallic tape only

OF

SITE

5

Use the tape continuously to mark c/c distances.


6

Center line marking for the first floor slab.


• After marking starters must be put for the columns.

• Starter concrete should be the same as that of the column concrete.

7Fig - 3

Fig - 2


• Column alignment must be checked to plumb.• Here the column is out of plumb.

8

Fig - 2


Excavation

1.It includes digging a pit for the foundation.2.Excavation for footing depth should be done as per the specification given by the structural Engineer.

9

Fig - 4


Consolidation

1. The excavation pit should be thoroughly consolidated before sand filling.

2. If the filling part is more then 2ft in an excavation pit the consolidation should be in layers.

3. The consolidation water must be dried before laying PCC to avoid air cracks in the floorings.

Sand filling & PCC

10

Sand filling & PCC

1. Sand Filling and PCC are done as per the Structural Drawing

2. After dewatering the sand filling must be done depending upon soil condition as recommended by structural engineer.

3. While sand filling & PCC the G.L should be plain otherwise the column may slide.

4. Sand should be watered before laying PCC.


11

Level with PCCFig - 5 Fig - 6

1 Structure consists of footing, column up to basement,

pedestrian, plinth beam, columns above, roof beam &

slab some cases lintels also provided again first floor

columns as so on.

2 While laying the footing concrete the column rods should

be to plumb after completion of vibrating.

12

R.C.C Cover blocks and clear cover

Standards for Clear Cover:

Structure Size of Clear Cover

FOOTING 50mmPLINTH BEAM 25mm


PLINTH BEAM 25mmCOLUMN 40mmBEAMS 25mmSLAB 15 to 20mmLINTELS 20mm

Cover Blocks1. Cover Block should be cast 28 days before casting the footing, column,

beam or slab in order to cure the cover blocks.

2. Cover Blocks should be cast using the same mix proportion of the one used for construction of footing/plinth beam/columns/beams/slab.

13

3. While casting the cover blocks provide a binding wire at the top which helps the labour to tie up with the reinforcement during the construction of footing/plinth beam/columns/beams/slab. This will keep the reinforcement within the fixed position.

4. Not only for the bottom reinforcement but also for the top reinforcement these cover blocks should be provided. Generally 2”PVC pipes are used for the preparation of these Cover Blocks.


14

5. Left over mix should not be used for the development of clear cover.


15

• The round cover blocks are for the top reinforcement.


16

1. Cover Blocks are being placed before concreting.

2. Cover Blocks must be placed at min1M C/C

3. Cover Blocks must be of the same composition of that of slab concrete.


1. While Concreting cubes must be taken to ensure the quality and strength of concrete.

2. 4 Cubes each to be tested by the department at intervals of 7 days, 21 days and 28 days and one to be preserved.

17

Shuttering

1. Shuttering for the beam sides must be removed on the next day itself.

2. While concreting the applied waste oil should be flushed out in the beam form work .

3. Always see that the top slab plain and the variations in thickness should be kept in bottom slab while in form work.


4. Depth of the beam & slab sizes to be checked through while shuttering.

5. No shuttering to be carried without laying p.c.c for floor ( ground).

6. For spiral staircases mud shuttering is used with levels.

7. Proper nails should used depends upon the shuttering and nails should be carried in iron tub.

18

Precautions to be taken to the end Precautions to be taken for staircase shuttering beam while shuttering.

beam while shuttering.


19

• Staircase done by concreting and not by bricks.

20

In some cases, if shuttering is to be carried out over consolidated gravel (with out PCC) then the following precautions to be taken-1. Well compaction of soil with earth compacter/roller.2. Below the posts wooden plank must be provided.


21

Double shuttering is to be provided in case of greater heights. Proper bracing to be provided to this shuttering.


22

The centering supports of the beams and slabs must be in vertical but not inclined

Bad Practice

After centering is completed all the holes at the joints must be finished with tar sheets so that concrete slurry will not drop down.


23

The centering must be lowered or kept up depending on the slab thickness.

• V- Joints ( Wooden Planks) to be removed before laying the concrete.


24

Steel Reinforcement

• Corroded steel should not be used.

• Column bars on the top most slab must be bent into the slab before concreting

• Bar bending should be carried out as per the drawing given by the structural engineer,

• Notice to be given to the structural engineer while changing the reinforcement in some


• Notice to be given to the structural engineer while changing the reinforcement in some cases.

• For ex. proposed 2nos 20mmØ is to be provided as per the drawing as the top bar and if availability of steel is 16mm Ø we can use 3 nos instead of 20mm Ø 2nos with structural engineers permission.

25

• There must be a ring at the bottom mostlevel so that the column will not go out of plumb.


26

1. If you do not put the lower ring the column will go out as shown in the photograph. The result is to bend the column

reinforcement.

Bad Practice

• Overlap length should be 40d for columns and compression members , and for slabs and tensile members it is 50d.

• The bars should be overlapped from inside only, no bar must be tied from outside of the main bar.


27

1. Over lap should be properly executed by bending the reinforcement bar in such a way that both the

reinforcement is in one line.2. It should be specially noted that the overlap should be towards inside.

• In a length of one floor there must be on overlap joint.

• 50% of the joint must be staggered.


28

1. The overlapping of rods must not be at the slab level.

2. If it is at the slab level beam rods will be difficult.

• Column top must not be smooth • Bonding wil lnot be perfect.• It should be made rough.

30

Reinforcement details for beams


31

Here we will not get the design depth

Construction joint

1. When we stop concreting for lunch break or after days work we will be joining oldconcrete with the new. That joint is called construction joint.

2 Construction joint should be provided at the beam slab joint as shown in the fig.

3 When we re start concreting joint must be cleaned properly and lose particles must be removed with flushing of water and wire brush and 1:1 1/2 slurry must be applied.


removed with flushing of water and wire brush and 1:1 1/2 slurry must be applied.

32


33

Preventive measures to be taken to avoid terrace leakage.

a) Right at the time of shuttering providing for last slab natural slope.

b) Educate the site engineers to provide proper Openings/Ducts for sewage/Sewerage/Water/Electrical lines etc. so as to avoid cutting of beams.


sewage/Sewerage/Water/Electrical lines etc. so as to avoid cutting of beams.

34

Bricks and

Plastering


Plastering

Different types of bricks available1. Clay Bricks2. Fly Ash Bricks3. Aerocon Bricks ( Light weight bricks)

Clay bricks


How to know the quality of the clay bricks

1. Randomly select a brick from the lot and place it in water for 24 hr the weight of the brick must not increased abnormally. Variation of dry weight and wet weight cannot exceed 10%

2. Bricks should give a metallic sound, If properly burnt.

3. A good quality brick gives in minimum wastage.

4. The bricks should be in proper shape and size.

36

Normally available size.

100mm x 100mm x 200mm ( 8” x8” x 4”) wire cut, factory made and chimney burnt.

230mm x 115mm x 75mm Normally manufactured in fields and burnt.

200mm x 100mm x 75mm Normally manufactured in fields using rice husk and burnt. ( light weight) normally known as Rajamandary bricks

Fly ash bricks• Normally made with Fly ash, Baby Chips and cement.


• Normally made with Fly ash, Baby Chips and cement.• The available sizes are

– 4” x 8” x 12” ( generally against order)– 6” x 8” x 12”– 8” x 8” x 12”The major use of this bricks are forall brick work, Partitions, Compound Walls

37

v Advantages Less cement mortar Less time.

v DisadvantagesClimatic changes cannot be controlled.While cutting electrical groves proper cutting cannot be executed.


• Solutions– Cutting should be done by cutting machine.– ( hand chisel cannot be executed)– electrical pipes should be fixed in a proper way.– Electrical/ Plumbing groves should be filled properly using small tools so that the

mortar goes all round the pipe and allow it to settle along with curing. Proper curing should be done before starting the plastering

38

Precautions while cleaning the site for brick work

v The sand and loose particles must be cleaned and washed.


vThe cement bunds used for curing should

be totally removed because it is made by

lean mortar.

39

Marking

v First layer of brick workmust be laid after the surface is properly cleanedand 1:2 cement slurry is properly applied. Base layer of 1:4 Have to be laid, leveled andproper line thread should


While marking outer wall plumb should be taken from the outer beam,

proper line thread should be used for achieving the alignment

The rooms must be either square and rectangle and see that the diagonal distance is the same. Perfection in marking can achieveExact shape

40

Marking• Marking should be done as per the drawing.• Broken bricks should not be used• We must ensure that the brick gets proper base over the beam. At times due to bad

shuttering the alignment of beams are not achieved. The after effect of that will be on brick work. Hence proper care should be taken while marking the brick work.

Different types of Bonds in bricks


Different types of Bonds in bricks• Bonds are the horizontal patterns in which bricks are laid. There are five main types of bonds

used in old buildings– The main three brick bonds are

1. Old English Bond

2. Flemish Bond

3. Stretcher Bond

41

vBricks must be kept in a tank of water sothat it absorbs waterand after that only brick work should bestarted other wise it absorbs water fromthe cement mortarand due to whichcracks will be formed

AlternativeThe bricks should be


vExtra mortar bulging out after every layer should be properly cleaned after every half day of work using broom or brush.

v After every layer of brickwork the top must be leveled with cement mortar.

The bricks should beproperly watered without wasting much water.

42

v At the column and brick joint the column should be washed with water, chiseled,1: 2 thickslurry must be applied.


v At no point of time4” wall shall be constructed

more then 3’ height in a day and 9” wall 4’ height to 5’0”.

vIn 4” wall layer of RCC with 2nos-6mm rods at 3’ height( Sill level) and the second layerat lintel level. This is called RCC bond. This will strengthen the wall against buckeling.

43

v The wall to wall joints should be provided as shown in the figures.

v The joints between twobricks should be properly filled.


v The brick to brick gap whenlaying in a row should be 12mm for the cement mortar.

4” brick wall

9” brick wall

vWhen Finger is placed horizontal it must exactly go into the gap.

Thumb Rule

44

vBrick work shouldbe to plumb otherwiseIt leads to more thickness Of plastering waste of money and time.

vAt the beam and brick joint care


should be taken because beam tends to expand. So a small gap should be created by placingcard boardsheet or 12mm thermo cool sheet in between beam and brick layer .( Top layer below beam)

45

Bricks joints are the causes of leakage


Bad workmanship

46

RCC Lintel

Now a days we are notusing this projections


Better to have CC beltover parapet to level to avoid shear cracks.

Belt Concrete

using this projections in wood work.

47

Electrical pipes ( Concealed) should be properly filled with brick bats and mortar beforeplastering


48

Latest we are getting anchor bolts with which

Wooden frames either door frame or window frames clamps concrete should

Use chicken mesh back side of electrical boxes in 4” walls for better strength


anchor bolts with which we can fix windows, doors etc

clamps concrete should be done properly other wiseit leads to cracks at all round the frame

For ventilators also proper base should be given

49

• Plastering

• The wall surface should be Cleaned before plastering.

• Cement Mortar used for plastering should be mixed thoroughly.

• It is the general practice to mix 3 to 4 bags of cement for mortar in the morning which is used till lunch time this is a very bad practice because cement looses its strength.


till lunch time this is a very bad practice because cement looses its strength.

• Advanced countries these type of mortars are mixed and kept dry in bags just like cement bags. As per the requirement they add water and admixtures for workability before using.

• Water cement ratio should be maintained to achieve workability.

50

Ceiling Plastering

1. To remove all the left over pieces of shuttering materials.2. Chip out the extra concrete – any bulged portion. 3. Clean with wire brush carefully. Now a days wire brush attached to motorized hand machines are available4. Clean with water jets on the proposed plastering surface.5. See that waste oil particles are cleaned properly.


5. See that waste oil particles are cleaned properly.6. Hacking/ Chiseling should be done properly.In general practice – This is for grip of cement mortar to the slab. 7. Thickness of the plastering is 10mm to 12mm. If the thickness is more the plastering may peel off.8. While plastering extra care should be taken to avoid air pockets between the plaster and slab.9. Perfection should be achieved at the corners of slab and beam.10. Excess mortar which has fallen on the floor while plastering must be thoroughly mixed before reuse.

51

Internal Plastering1. The brick work should be watered thoroughly before plastering.

2. In plastering see that laths (ammakalu) are used to mark thickness of coat required. Laths should not be more that 1.5m apart. ( This is the length of badda used for plastering)

3. In two coat work the first coat should not exceed the specified thickness and should be kept for 7 days before second coat is applied.


for 7 days before second coat is applied.

4. Ensure that the plastering is even and in plane. All precautions should be taken to ensure proper grading of sand, mixing of mortar, and curing after the work is completed.

5. See that all electrical pipes are levelled to the brick work. Electrical conduits must be filled with cement mortar two days before .

6. The plastering surface should be thoroughly finished with trowel for good finish and to avoid air cracks.

7. While plastering on R.C.C surfaces check that it is properly hacked and cleaned .

52

• External Plastering

• 1. The portion where the plastering is been carried out should be thoroughly watered.• 2. In plastering see that laths (ammakalu) are used to mark thickness of coat required. Laths

should not be more that 1.5m apart.• 3. When you are starting from the top portion the laths should be done till the bottom and

should be to line.• 4. Where ever there are beam and brick joints see that mesh is being fixed 6” below the joint


• 4. Where ever there are beam and brick joints see that mesh is being fixed 6” below the joint on to the brick work and 6” above the joint on the beam. There is problem to nail on the beam so go till the top brick work.

• 5. A slant coping must be provided at the parapet wall top with concrete.• 6. All the beam (bottoms) and brick work joints care to be taken to avoid seepage.

– In general practice : Before plastering all brick joints must be filled with rich mortar and especially beam joint dully filled with rich concrete.

7. Scaffolding holes must be duly filled with concrete or brick bats only, but not with plain mortar.

53

Sunshades

• When doing sunshades nosing must be done 4” above every sunshade, this prevents rainfall from entering the sunshade and brick joint.

• Sunshades should be provided with water patti all round.

• The sunshades should be 6” more on either side then the windows. This prevents rain fall


• The sunshades should be 6” more on either side then the windows. This prevents rain fall from entering from the window.

• The sunshades must be 2’ in width.

• Brick work and sunshade joint on top of the sunshade coping concrete with baby chips must be laid to total length of the sunshade and plastering must be done continuously (The coping concrete and plastering must not be joined after the total plastering is completed).

54

Preventive measures of cracks in bricks

How to prevent cracks in buildingCracks in building are a common occurrence and it is important to understand the causes and the measures to be taken for their prevention. Materials such as bricks, mortar and concrete, which contain considerable quantity of water at the time of construction, dry out subsequently and under go major contraction.

GENERAL MEASURES FOR PROTECTION OF CRACKS.The measures for prevention of cracks could be broadly grouped under the following main sub heads.


sub heads.

a) Selection of materials:-Good quality of building materials according to the specification if used that will minimize the cracks in the building.

b) Specification for mortar and concrete:-The ratio of the mortar and concrete should be according to the prescribed design. Care should be taken that the coarse aggregate, fine aggregate should be free from silt suspended impurities and the mix should be homogeneous, well mixed and contain no excessive of water.

55

Preventive measures of cracks in bricks

c) Drawing and Design of the building:- While doing the construction work care should be taken that foundation of the building should not be laid on loose /muddy soil. The mortar, M S steel reinforcement should be according to the design.

d) Good Construction practices:-It is necessary that work proceed uniformly in all part of building. The workmanship should be according to the prescribed norms and best practice in the building construction.

e) Weather Effect:-The construction work should be avoided in very hot and dry weather, and


e) Weather Effect:-The construction work should be avoided in very hot and dry weather, and during very low temperature also. In general quality of water, sand ,Bajri , mixing of mortar ,quantity of water in mix , socking of bricks and workmanship have great effect on construction work. If possible the subsequent items of construction should be done after the drying of work previously done.

56

Vertical cracks in long compound wallCauses :-

Leaving expansion/contraction joints at proper interval ,in cold weather when the wall tense to contract due to temperature drop but being not allowed to contract freely.It develop tensile stress and when the tensile stressexceed the strength, the wall cracks. Similarly in hotweather wall tends to expend and if expansion is notallowed to occur freely compressive stresses will


allowed to occur freely compressive stresses will develop in the wall and when they exceed the strength,wall will break.

PREVENTIVE MEASURES

Leave expansion/contraction joints at regular interval specially in long stresses of wall.

57

Cracks in load bearing masonry wall below RCC slab

Causes:-Absence of slip joints between RCC slab and wall does not allow RCC slab to move freely over wall and leads to cracking in the wall.

• Some times the movement of the slab may also causecracking in masonry at lintel and window sill level


cracking in masonry at lintel and window sill level because here is the masonry is weak. These cracksare observed mainly on the top most story of thebuilding because roof is more exposed to temperature variation . PREVENTIVE MEASURES :-

• Before casting RCC slabs over brick wall , smooth bearing plaster should be done over brick walls coupled with white wash / bitumen coating over it. It allowed slab to move freely over wall .

58

Vertical Formation of cracks at the base of parapet wall

Causes :-An instant of very frequent occurrences of thermal cracks in building is the formation of horizontal cracks at the sport of a brick parapet wall.


brick parapet wall.

Factors which contribute to this type of cracking are

a) Thermal coefficient of concrete is twice that of brick work and thus differential expansion and contraction causes a horizontal shear stress at the junction of the two materials.

b) Drying shrinkage of concrete is three to four time that of brick masonry.

c) Parapet are generally built of concrete slab before the latter has undergone its drying shrinkage fully . Parapet or railing does not have much self weight to resist horizontal shear force at it sports caused by differential thermal movement and differential drying shrinkage.

.59

PREVENTIVE MEASURES :-

Construction of masonry over the slab should be deferred as much as possible ( at least one month ) so that concrete under goes some drying shrinkage prior to construction of parapet. Mortar of parapet masonry should be rich and a good bond should be ensured between masonry and concrete. Plastering on masonry and RCC work should be deferred as much as possible and made discontinuous at the junction by Providing V groove in plaster. This way the cracks if occur , will get concealed behind the groove and not be conspicuous. In case of iron railing , cracks could be avoided by substituting the brick work with a RCC wall, sporting


iron railing , cracks could be avoided by substituting the brick work with a RCC wall, sporting RCC railing

60

Vertical cracks at junction of main wall and cross walls

Causes :-

Improper bonding of cross walls with main walls by notleaving proper keys in the main wall.


PREVENTIVE MEASURES :-Main and cross walls should be properly bonded by propertoothing.

61

Vertical and horizontal cracks in panel walls in RCC framed structureCauses :-Panels wall are built very tightly to the RCCbeams so that RCC beams are not free to deflect, load is transmitted to the wall and vertical and horizontal cracks are produced in the wall depending upon the direction inwhich wall is more slender


which wall is more slender ( i..e. Along height or length ) .

PREVENTIVE MEASURES :-Some gap should be left between top of panel wall and bottom of the beam/slab so that beam can

deflect freely. This gap can be filled by weak mortar. If lateral support is required to be given to wall beam/slab then some special lateral connections can be made in such a way that free deflection of beam is not hindered in vertical direction.

62

Horizontal cracks in the top most story below slab:-

Causes :-Cracks are due to deflection of slab and liftingup of edge of the slab. Cracks are mostly confined to the top most story because of light vertical load of parapet wall on slab due to which end of the slab lifts. These cracks normally occur


which end of the slab lifts. These cracks normally occur in roof slabs of large span.


a) Bearing plaster should be done on top of wall below RCC slab with a coat of white wash or bitumen.

b) Avoid large spans of roof slab , if possible provide beams to reduce the length of the slab.

63

Diagonal cracks in panel walls in RCC framed structure

Causes :-

When RCC frame moves/deflects due to loads, temp,variation etc. it causes diagonal cracks in walls which are located parallel to the movement.


which are located parallel to the movement.


Walls should not be build tightly to the columns. For taking lateral supports from column, special connections should be made between wall and column which provide lateral supports to wall but does not tie it too tightly to the column .

.

64

Vertical cracks below openings in line with window jambs

Causes :-These cracks are caused due to vertical shear caused by differential strain in the lightly loaded masonry below the opening and heavily loaded portion of wall having no opening.


wall having no opening. PREVENTIVE MEASURES :-

A) Too much disparity in stress in different walls orparts of a wall should be avoided.B) Portion of wall acting as pillars and having too much concentrated loads should be replaced by R R C pillars., if possible.

65

Arching up and cracking of coping above retaining/boundary wall

Causes :-Due to not leaving expansion joints wall & coping.


PREVENTIVE MEASURES :-Leave proper expansion joints in walls. Avoid long stretches of wall.

66

What we don’t want to happen in our buildings

What problems we don’t want to face


67

The complaints that we don’t want to receive from our customers

Seepage from wall and beam joints


68

Remedy

1. Proper filling of gaps, apply water proof chemical.2. Two coat plastering

1st coat 1:1 ½ with baby chips.2nd coat after curing of first coat.



69

Same as in the 1st page

Remedy



70



71


Lack of vertical alignment leading to seepage


72

This cannot be rectified only way will be to increase the with of the beam adding proper reinforcementand proper shuttering.



Proper filling and waterproof plastering

Remedy

73

Cracks around switch boards and along electrical conduits.


74

Remedy

Fill the conduits grooves with hand, fix mesh 3” extra either side and one coat plaster on grooves.2nd coat along with plaster after curing the 1st coat.



75


76

Seepage at sunshade and wall joint


Remedy

1. Remove loose particles.2. Round the wall shade with water

proof concrete 3. Apply hydrobond chemical4. Plaster with regular 1:4 motar.

77

Seepage at sunshade and wall joint


78

Seepage from traps in Balcony/ Kitchen utilities


Remove loose mortar around trap.Fill with baby chips, concrete with water proof chemical and grout around the tile finish.

Remedy

79

Seepage from terrace and parapet wall joints


80



81



82



Remedy

83

Seepage from toiletsQUALITY CONTROL IN CONSTRUCTION

84


85


86


87

Seepage from toilets

Remedy

Refer toilet Water proofing.


88

Seepage at the joint of plumbing pipe and wall joint


89

Seepage at the joint of plumbing pipe and wall joint


90

Remedy

Remove all loose mortar around plumbing pipe. Fill with baby chips,Concrete with water proof chemical.

Seepage with rain water outlet at terrace and at balconies


91

Remedy

Remove all loose mortar around plumbing pipe. Fill with baby chips,Concrete with water proof chemical.

Seepage with rain water outlet at terrace and at balconies


92

Problems arising at wall and wood work joints


93



94



95



Do not use the extrawood projections, after Plastering it will form Cracks. Instead use Clamps.

96

Cracks / seepage in top floor roof slab


97

Cracks/seepage in top floor roof slab


98

Cracks/seepage in top floor roof slab

Terrace treatment



99

RCC slab


Problems from puddles of water in sites


100



101



Remedy

Use these types of pipes for watering

102

Seepage due to outer scaffolding holes


103

Plumbing and and

Electricity

Plumbing – Toilets – water lines

• Marking your bathroom layout.

1. Before marking of the toilets first coat plastering must be completed.

2. The plastering must be 12” above Finished floor level of the room ( not the finished floor level of the toilet)

3. The sink and commode positions should be fixed before hand.3. The sink and commode positions should be fixed before hand.

4. The lines must be marked properly using a good plumber.

5. The hot water and cold water lines should be 6” apart and should not be more also.

6. The commode, sink must have separate multi traps.

7. For sink the sewage line can be with 50mm dia pipe.

8. For w/c the line must be 110mm dia .

105


106

• Modern toiletsMulti trap

2’0” wet Area Wall Mixer

F.L is 1” below F.L of toiletCloset

W/c

Dry Area

Wash Basin

Multi trap

Min 6”• If toilet size is 6’x4’.

107


108

We recommend to go forplastering first and thengrove cutting for water pipe line

Plumbing- toilets – Sewage lines1. Weather it is low level slab or high level slab surface cleaning should be the first job means removing loose particles, chipping all slurry scales etc. Achieve the virgin concrete. 2. Observe whether there are any cavities left in beams/slab. If so grout the same.3. Lay all the sewage floor pipes and test for cleaning and fill all the holes made for the pipes. Seal the same perfectly. Fill with the guidance of any water proofing company. Plumbing- toiletsPlumbing- toilets

• Some of the points to be followed while fixing the tap points

– 1. Height of the kitchen tap must be 9” from the Kitchen platform– 2. Height of kitchen platform is 33” from the F.F.L to top of granite top.– 3. In the toilets

• 1 Height of wash basins is 70cm from F.F.L this is with pedestal• Height of Shower is 7’.0”.• For health facet height is fixed at 2’0” for W/C.• For Indian commode the height will be reduces by 6”..

109

Plumbing- toilets – water lines

110

• In bathrooms and kitchens only after the plastering is completed the internal water pipe line should be laid.

– Reason:- Taps to the plumb.

• Multi traps or nani traps should be provided in kitchen utility and in bath areas ( where ever it is connected to the drain).

– Reason:- This acts as a water seal.– Replacing gully traps in older days.– Replacing gully traps in older days.

• All the external plumbing line’s should be done after the plastering is completed.– Reason:- Water leakage

• The water outlet must be different for bathing area and commode area.

• Adequate slope of the pipes connecting the bathrooms/ kitchens to the main line.– Reason:- Materials may be stuck if slope is less.

111

• While joining bathroom out let to the main line care should be taken to provide ‘Y’ joint but not ‘T’ joint.

112

• When concreting for water tank walls see that the out lets are provided at the bottom.

• There must be two pipe provision one 2” above the inside floor level of the tank. This is used for connecting the tank to the pipe line and the other at the floor level for cleaning purpose.

• There must also be a over flow pipe from the tank. This must be 3” below the water tank slab.slab.

• Before water proofing– 1. Internal plastering should be completed– 2. Internal water supply lines should be completed only then 1st course of water proof

layer should be done. – 3. After the first layer of water proofing only internal sewage lines must be laid.– 4. After laying the sewage lines second layer of water proofing should be done.

114

plumbing

115

After second layer water proofing

116

Electrical

• While plastering ensure that the D.B is covered by a polythen cover or D.B protection covers so that the cement mortar does not go into it.

• All the boards also the same procedure must be followed other wise while fixing the switches cleaning will be a big problem.

• Ensure that the pipes back side is properly filled with mortar ( there must not be any voids) before plastering.

• Before starting the wiring let the supervisor along with electrician calculate the amount of • Before starting the wiring let the supervisor along with electrician calculate the amount of wires of different gauge required.

– Fridge :- only 5Amps plug is enough.– AC and Heater’s we provide 15 Amps.– Lights :- 0.75 Sqmm wire is enough.– Always go for lower amp’s MCB so that it trips of if the socket is over loaded.– ELCB is compulsory.

118

Electrical

• Service lines through the beam at mid landing should be avoided.– Alternative :- Provide 2” gap for the pipes at mid landing.

– To many pipes adjacent to each other with any gap should be avoided, both in the slab and in the walls

119

electrical

120

In the above pipe is run cutting the concrete.This where creaks form.

121

When the electrical pipes are passing across the columnIt is always not to chip the column.

electrical• In the last floor avoid laying pipes in the roof slab.

– If it is unavoidable we better go for a 6” thick slab.

122

Mesh work

• Mesh work must not be done at all as mesh work is done by mortar and mortar has a tendency to form cracks when exposed.

• It is better to cast the same with RCC. The thickness will be more but this is a safe practice.

123

PAINTING

1. First of all painting is not only for decoration in 1st part it protects the surface from weather in the second part. This has to be thoroughly understood by everybody.

• Even though I mention the protection as second part, you will know that protection is the 1st

part. Protection varies from place to place like• Extreme weather condition • Extreme weather condition

(a) Sea coast area (b) Heavy rain fall area• In all the case the final aim is to preserve the building .• Look at an example• We buy a scooter we cover it with something to protect from weather• We wear dress, cotton silk, wool depending upon weather• In building how to achieve the same• Here comes the paint• We clean our body by taking bath/wash and wear dress

124

• In building it is called surface preparation clean the part like metal, wooden, cement, Brush etc., wipe with dry cloth using emery paper, wire .

• Apply 2 coats of primers-Metal/wood/cement. Never do painting in damp conditions or rainy day or even in gloomy weather. Apply only when there is bright sunlight. Your painting quality improves and longevity of paint increases in bright sunlight.

• Always see that there is at least 2 days gap is given for each coat over the primer you can apply any paint colour (here comes beauty) as per your choice.

• Do not apply lime white on other than

• Dark colours tend to fade when exposed to direct sunlight.

125

Responsibalities of Structural Designers:

1. Visit the site once excavation is completed. This will enable the designer to make any changes in foundation .

For example:a) There can be some wells or pits filled with debris etc.,b) Over lap of footings unnoticed.c) Surprise checks of site to verify the execution is done as per design and column

overlaps are as per norms and shuttering props/ bracings etc., are safe.


overlaps are as per norms and shuttering props/ bracings etc., are safe.d) Verify the reinforcement before casting of slab/beams and suggest proper

construction joint.e) Suggest the precautions to avoid cracks on slabs on the next day of casting

especially when R.M.C is used.f) Suggest the safety factors to be observed by the work force so as to avoid

untoward incidents.g) Proper guidance to site engineer for staircase, low level slabs to avoid toilet

leakage and building of external beams.

126

Responsibilities of Site Engineers:Technical, Administrative, Social

1. Material storage at site/road margin cause inconvenience to commuters/neighbours. Remedy: Creating a bund all round. Solves the problem & also saves waste of material.

2. Park your vehicles , your material trucks, Concrete mixers etc., without blocking traffic.3. Don’t damage roads/drainage while construction. Always think the property is yours not municipality/panchayat/corporation/VUDA/government.


municipality/panchayat/corporation/VUDA/government.4. While engaging night work avoid disturbing neighbour or seek their co-operation/advance permission. Confrontation leads to litigation and mental agony.5. Extra care to be taken to avoid choking of public drainage systems.6. Always keep a dustbin at site.7. To minimize the material wastage in the site .8. Check the quantity of material properly.9. Inspect weather any mud particles are there in the sand or not.10. Test o know which is sea sand and river sand. Test:- Mix sand with water in a test tube and add 10 drops of silver nitrate solution. If the water turns to milky colour then the sand is sea sand if not it is river sand.

127

• This plays major role at any site:• Site engineer is a Bridge between builder and contractor. He should be impartial at that

point. His job is to convince both of them as per circumstance. Again he is a bridge between contractor & Accounts. Here the job is to facilitate fund flow to the contractor from company depending on the progress of work without causing loss to both the parties. For this he should have the through knowledge of the progress of work everyday. He should develop the quality of judging the value of work executed every day. It is the responsibility of site engineer to access whether the rate Quoted by the contractor is workable or not. It is the engineer to access whether the rate Quoted by the contractor is workable or not. It is the responsibility of site engineers to convince the owner/builder/contractor to come to arrive at a common point.

• How can we achieve this? • Depute 2 or 3 workers on that particular job. Observe the output .Arrive at the unit rate add

for contingencies like tools, add 20% profit for the contractor, you must also observe the overheads of the contractor like his transport etc., Then come to the final rate.

• While doing this the site engineer should observe whether the people deputed are fully on the job. There is a second method to arrive at this.

• Develop the habit of generating daily report. Look at the man power used for that particular job and evaluate the cost.

• 128

• This method is applicable for every job right from excavation to till painting. With this type of data you are the people to update the records of Consultants/Architects for evaluations of cost.

• Daily report is a fundamental discipline of a site engineer. This provides the record of supply of material like sand, metal, cement, etc. which are entering the site, Daily consumption of cement, and arrest any pilferage.

• Site engineer is the first doctor of any site, he has to be well trained for the site to face any • Site engineer is the first doctor of any site, he has to be well trained for the site to face any contingents occurring at the site. He should be alert to direct the victims of minor cuts, falls etc. happening at the site. His proper response improves the image of the company.

• Site engineer is responsible in explaining the flat details to the prospective purchaser. Generally place like Viziaganaram and small builders cannot afford to have a markiting department. Hence the site engineer should have a good communication skill.

• Site Engineer should see that the workers employed at the site and working at height wear their safety belts and helmets. First of all he himself should be with proper shoes and helmet.

• Site Engineer should arrange a proper path way for visitors to enter the construction site/ modal flat. And the route should be so protected that nothing untoward happens while moving.

129

Ould be

• Site engineer should receive all the officials who are visiting the site for inspection or verification and answer to the questions of the officials with full responsibality.

• He should have a check list before handing over the apartment/ Building.• Tips

– 1. Check whether the yard lighting is proper .– 2. Main door lock and internal tower bolts are intact.– 3. All the toilets locks/ tower bolts from inside are proper.– 4. All the taps are intact and water flow is perfect.– 5. Whether the flushing system is working .– 6. Kitchen sink and water supply.– 7. Drainage flow in toilets and closets. ( Generally all these are either packed at the time

of construction or painter pour the paints and the drain gets choked.– 8. Verify all light and fan points.– 9. Proper lock and key for bed rooms.– 10. All window shutters are perfect.– 11. All the floor joints are properly grouted.– 12. Kitchen platform gas hole is provided.– 13. Utility drainage is functioning properly.– 14 See that walls and shutters are painted properly.

(Clean the paint dots which are falling over the hard wear.15. Maintain register for each flat entrance door key number.16. Check the height of the vision eye piece properly.

Daily report sheet is attached for your kind information 130


131

All round coverage of building as itprogresses so that it does not damage neighbours building.

Difference between RMC and Cast in-situ

R M CDis-advantages :-1. RMC contains % of fine aggregate + sizes of aggregate smaller of size + admixture.2. Admixtures causes air cracks in most cases.

Remedy:- Trovel the surface after casting for 3 hours.


Remedy:- Trovel the surface after casting for 3 hours.Advantages :-No need of material staggering in the site, takes less time, No water arrangment required, No disturbence, No labour modilization, No wastage of materialCast in-situDis-advantages:-Arranging of water for concreting is necessary, Labour modilization, Wastage of material, DisturbenceAdvantages1. Perfect size of aggregate + sand

• 2. Proper cement used so no air cracks develops,

132

General Topics• After drilling the bore well point it should be covered with a cap.

• All concrete work should be machine mixed.• Before mixing the concrete (aggregate) metal should be washed thoroughly.• Cement should be stored on a platform made of bricks or bamboo posts and should be

covered with tarpoline.


covered with tarpoline.• Never close the reinforcement abruptly. The top reinforcement of the column must be bent

inside the slab.• Flaky aggregates should not be recommended.

Sand used for construction should be crystal and river sand.• If 20mm or 40mm aggregate contains any dust & mud particles should be washed before

using for construction.

133

• Quantity of load should be checked .

136

Quality Control in Construction12.Doc

Documents

Transcript of Quality Control in Construction12.Doc