Merits of Concrete Construction

Merits of Concrete Construction

1.Good Control over cross sectional dimensions and Shape One of the major advantage of concrete structures is the full control over the dimensions and structural shape. Any size and shape can be obtained by preparing the formwork accordingly.
2.Availability of Materials All the constituent materials are earthen materials (cement, sand, crush) and easily available in abundance.
3.Economic Structures All the materials are easily available so structures are economical.

4.Good Insulation Concrete is a good insulator of Noise &  heat and does not allow them to transmit completely.

5.Good Binding Between Steel and Concrete There is a very good development of bond between steel and concrete.
6.Stable Structure Concrete is strong in compression but week in tension and steel as strong in tension so their combination give a strong stable structure.
7.Less Chances of Buckling Concrete members are not  slim like steel members so chances of buckling are much less.
8.Aesthetics concrete structures  are aesthetically good and cladding is not required
9.Lesser Chances of Rusting steel reinforcement is enclosed in concrete so chances of rusting are reduced.

Demerits of Concrete Construction

1.Week in tension Concrete is week in tension so large amount of steel is required.
2.Increased Self Weight Concrete structures have more self weight compared with steel structures so large cross-section is required only to resist self weight, making structure costly.

3.Cracking Unlike steel structures concrete structures can have cracks. More cracks with smaller width are better than one crack of larger width

4.Unpredictable Behavior If same conditions are provided for mixing, placing and curing even then properties can differ for the concrete prepared at two different times.
5.Inelastic Behavior concrete is an inelastic material, its stress-strains curve is not straight so its behavior is more difficult to understand.
6.Shrinkage and Creep Shrinkage is reduction in volume. It takes place due to loss of water even when no load is acting over it. Creep is reduction in volume due to sustained loading when it acts for long duration. This problem is not in steel structures.
7.Limited Industrial Behavior Most of the time concrete is cast-in-situ so it has limited industrial behavior.
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Important Tests on Bricks You Should Know

*8 IMPORTANT TESTS ON BRICKS YOU SHOULD KNOW*
*BRICK TESTS:*
Bricks are the most common and useful building materials used for masonry construction works. To build a long lasting structure we should always use good quality bricks and other building materials. In our previous article, we have already discussed the types of bricks used in construction. Today we will discuss some important brick tests to determine the quality of bricks. The common brick tests performed on the field as well as in the laboratory are described below.
*1. COMPRESSIVE STRENGTH TEST:*
This test is performed to determine the compressive strength of bricks. It is additionally known as crushing strength test of bricks. Normally, 5 samples of bricks are selected and transported to the laboratory for testing. A brick sample is kept on the crushing machine and then the pressure is thoroughly applied axially until it breaks. The maximum pressure at which the brick starts to crack is noted. The test is repeated with all 5 brick samples one by one and the average result is considered as the compressive strength or crushing strength of bricks.

*2. WATER ABSORPTION TEST:*
In this test, bricks are weighed first in dry condition (W1) and then they are fully submerged in water for 24 hours. After immersion of 24 hours, the bricks are collected and weighed again in wet condition (W2). The difference of weight between dry and wet condition is considered as the water absorbed by the bricks. Then the amount of water absorption is determined in percentage.
Water absorption (%) = [(W2-W1)/W1] * 100
The less water consumption by the bricks indicates their greater quality. A brick will be considered as good quality if it does not consume more than 20% water of its own weight.
*3. EFFLORESCENCE TEST:*
This test is carried out to obtain the presence of alkaline substances in bricks. First, bricks are fully submerged in fresh water for 24 hours. After 24 hours they are collected from water and left them to dry. After completely dried the bricks are closely observed to find the presence of alkali. If a white or gray layer is formed on the brick surface, it means alkali is present in the brick.
                                    *Observation*                              ————– *Efflorescence*

No Deposition—-Nil

10% of the brick surface. Slight (Ok)

———10% – 25 % of the brick surface. Moderate

25% – 50% of the brick surface. ——–Heavy

>50% of the brick surface. Extreme (Serious)

*4. IMPACT TEST:*
In this test few bricks are dropped from 1-meter height. If bricks are broken it indicates low impact value and not acceptable for construction work. Good quality bricks do not break at all.
*5. DIMENSION TOLERANCE TEST:*
20 bricks are randomly collected and arranged in a straight line. This is done to see the variation of shape, size, and color with the standard bricks.
*6. SOUNDNESS TEST:*
In this test, two randomly selected bricks are hardly punched with each other. If they produce a clear metallic sound and remain unbroken then they are good quality bricks.
*7. HARDNESS TEST:*
This test is done to know the hardness of bricks. In this test, scratches are made on the surface of the brick by a hard thing. If it does not leave any impression on the brick surface then it will be considered as good quality bricks.
*8. STRUCTURE TEST:*
In this test, a brick is fractured and firmly investigated. If any flaws, holes or cracks are seen inside the broken brick, then it is considered as poor quality brick.

Civil Site Engineer Must Know

Civil Site Engineer Must Know

One Way Slab:

The ratio of longer span panel (L) to shorter span panel (B) is equal or greater than 2. Thus, L/B >= 2.

Main reinforcement is provided in only one direction for one way slabs.

Two Way Slab:

The ratio of longer span panel (L) to shorter span panel (B) is less than 2. Thus, L/B < 2.

Main reinforcement is provided in both the directions for two way slabs.

Minimum thickness of slab is 125 mm.

Compressive strength of Bricks is 3.5 N /mm2.

Maximum Free fall of concrete allowed is 1.50 m.

Earth work excavation for basement above 3 m should be stepped form.

Electrical conduits shall not run in column.

Dimension tolerance for cubes + – 2 mm.

In soil filling as per IS code for every 100sqm 3 sample for core cutting test should be taken.

Lapping is not allowed for the bars having diameters more than 36mm.

Minimum bars of square column is 4 bars and 6 bars for circular column.

Samples from fresh concrete shall be taken and at least a set of 6 cubes of 150mm shall be prepared and cured. 3 Cubes each at 7 days and 28 days shall be tested for compressive strength. The test results

Should be submitted to engineer for approval. If results are unsatisfactory necessary action/rectification/remedial measures has to be exercised.

Slump IS 456

Lightly reinforced 25 – 75 mm

Heavily reinforced 75 – 100 mm.

Curing Days Required

Super Sulphate cement: 7 days

Ordinary Portland cement OPC : 10 days

Minerals and Admixture added cement: 14 days

A set of cube tests shall be carried out for each 30 cum of concrete / each levels of casting / each batch of cement.

PH value of the water should not be less than 6.

Lapping is not allowed for the bars having diameters more than 36 mm.

Adv

Basic knowledge of Site Engineer

Basic Knowledge of Site Engineer

Following few general points to remember for site engineers to make the construction work easier while maintaining the quality of construction.
Lapping is not allowed for the bars having diameters more than 36mm.

Chair spacing maximum spacing is 1.00m or 1 no per 1m2.

For dowels rod minimum of 12mm diameter should be used.

Chairs minimum of 12mm diameter bars to be used.

Longitudinal reinforcement not less than 0.8% and more than 6% of gross C/S.

Minimum bars of square column is 4 numbers and 6 numbers for circular column.

Main bars in the slabs shall not be less than 8mm (HYSD) or 10mm (Plain Bars) and distributors not less than 8mm and not more than 1/8 of slab thickness.

Minimum thickness of slab is 125mm.

Dimension tolerance for cubes +- 2mm.

Free fall of concrete is allowed maximum to 1.50m.

Lap slice not to be used for bar larger than 36mm.

Water absorption of bricks should not be more than 15%.

PH value of water should not be less than 6.

Compressive strength of bricks is 3.5N/mm2.

In steel reinforcement binding wire required is 8kg per MT.

useful Notes for Civil Engineers

Useful Notes for Civil Engineers 
CONCRETE GRADE:

M5 = 1:4:8

M10= 1:3:6

M15= 1:2:4

M20= 1:1.5:3

M25= 1:1:2
CLEAR COVER TO MAIN REINFORCEMENT:

1.FOOTINGS : 50 mm

2.RAFT FOUNDATION.TOP : 50 mm

3.RAFT FOUNDATION.BOTTOM/SIDES : 75 mm

4.STRAP BEAM : 50 mm

5.GRADE SLAB : 20 mm

6.COLUMN : 40 mm

7.SHEAR WALL : 25 mm

8.BEAMS : 25 mm

9.SLABS : 15 mm

10.FLAT SLAB : 20 mm

11.STAIRCASE : 15 mm

12.RET. WALL : 20/ 25 mm on earth

13.WATER RETAINING STRUCTURES : 20/30 mm
WEIGHT OF ROD PER METER LENGTH:

DIA WEIGHT PER METER
6mm = 0.222Kg

8mm = 0.395 Kg

10mm = 0.616 Kg

12mm = 0.888 Kg

16mm = 1.578 Kg

20mm = 2.466 Kg

25mm = 3.853 Kg

32mm = 6.313 Kg

40mm = 9.865 Kg
1bag cement-50kg

1feet-0.3048m

1m-3.28ft

1sq.m-10.76sq.ft

1cu.m-35.28cu.ft

1acre-43560sq.ft

1cent-435.6sq.ft

1hectare-2.47acre

1acre-100cent-4046.724sq.m

1ground-2400sq.ft

1unit-100cu.ft- ¬2.83cu.m 1square-100sq.f ¬t
1 M LENGTH STEEL ROD I ITS VOLUME

V=(Pi/4)*Dia x DiaX L=(3.14/4)x D x D X 1 (for

1m length) Density of Steel=7850 kg/ cub meter

Weight = Volume x Density=(3.14/4)x D x D X

1×7850 (if D is in mm ) So = ((3.14/4)x D x D X

1×7850)/(1000×1000) = Dodd/162.27
DESIGN MIX:

M10 ( 1 : 3.92 : 5.62)

Cement : 210 Kg/ M 3

20 mm Jelly : 708 Kg/ M 3

12.5 mm Jelly : 472 Kg/ M 3

River sand : 823 Kg/ M 3

Total water : 185 Kg/ M 3
Fresh concrete density: 2398 Kg/M 3

M20 ( 1 : 2.48 : 3.55)

Cement : 320 Kg/ M 3

20 mm Jelly : 683 Kg/ M 3

12.5 mm Jelly : 455 Kg/ M 3

River sand : 794 Kg/ M 3

Total water : 176 Kg/ M 3

Admixture : 0.7%
Fresh concrete density: 2430 Kg/ M 3

M25 ( 1 : 2.28 : 3.27)

Cement : 340 Kg/ M 3

20 mm Jelly : 667 Kg/ M 3

12.5 mm Jelly : 445 Kg/ M 3

River sand : 775 Kg/ M 3

Total water : 185 Kg/ M 3

Admixture : 0.6%

Fresh concrete density: 2414 Kg/ M 3

Note: sand 775 + 2% moisture, Water185 -20.5 =

164 Liters,

Admixture = 0.5% is 100ml

M30 ( 1 : 2 : 2.87)

Cement : 380 Kg/ M 3

20 mm Jelly : 654 Kg/ M 3

12.5 mm Jelly : 436 Kg/ M 3

River sand : 760 Kg/ M 3

Total water : 187 Kg/ M 3

Admixture : 0.7%

Fresh concrete density: 2420 Kg/ M 3

Note: Sand = 760 Kg with 2% moisture

(170.80+15.20)

M35 ( 1 : 1.79 : 2.57)

Cement : 410 Kg/ M 3

20 mm Jelly : 632 Kg/ M 3

12.5 mm Jelly : 421 Kg/ M 3

River sand : 735 Kg/ M 3

Total water : 200 Kg/ M 3

Admixture : 0.7%

Fresh concrete density: 2400 Kg/ M 3

Note: sand = 735 + 2%, Water = 200- 14.7 =

185.30,

Admixture = 0.7%

M40 ( 1 : 1.67 : 2.39)

Cement : 430 Kg/ M 3

20 mm Jelly : 618 Kg/ M 3

12.5 mm Jelly : 412 Kg/ M 3

River sand : 718 Kg/ M 3

Water Cement ratio : 0.43

Admixture : 0.7%

Note: Sand = 718 + Bulk age 1%

M45 ( 1 : 1.58 : 2.26)

Cement : 450 Kg/ M 3

20 mm Jelly : 626 Kg/ M 3

12.5 mm Jelly : 417 Kg/ M 3

River sand : 727 Kg/ M 3 + Bulk age 1%

Water Cement ratio : 0.43

Admixture : 0.7%

M50 ( 1 : 1.44 : 2.23)

Cement : 450 Kg/ M 3

20 mm Jelly : 590 Kg/ M 3

12.5 mm Jelly : 483 Kg/ M 3

River sand : 689 Kg/ M 3 + Bulk age 12%

Water Cement ratio : 0.36 (188 Kg)

Admixture : 1.20%3

Micro silica : 30 Kg

Super flow 6.7% of cement

1 cubic meter contains 500 bricks

The Standard size of the 1st class brick is 190mm

x 90mm x

90mm and motor joint should be 10mm thick

So brick with motor=200 x 100 x 100.

Volume of 1st class brick = 0.19 x 0.09 X 0.09 =

0.001539

cu.m

Volume of 1st class brick with motor =0.2 x 0.1 x

0.1=0.002

cu.m

No. on bricks per 1cu.m= 1/volume of1st class

brick with

motor

=1/0.002

= 500 no’s of bricks
STANDARD CONVERSION FACTORS

INCH = 25.4 MILLIMETRE

FOOT = 0.3048 METRE

YARD = 0.9144 METRE

MILE = 1.6093 KILOMETER

ACRE = 0.4047 HECTARE

POUND = 0.4536 KILOGRAM

DEGREE FARENHEIT X 5/9 – 32 = DEGREE

CELSIUS

MILLIMETRE= 0.0394 INCH

METRE = 3.2808FOOT

METRE = 1.0936YARD
A rope having length 100cm.You can form any

shape using this rope (Example: Triangle,

Rectangle, etc.,). Which shape will covers

maximum area
1 Newton = o.101971 kg

1 mm2 = 0.01 cm2

1 cm2 = 100 mm2

1 mm2 = 20 N

100 mm2 = 2000N

1 cm2 = 2000N

2000 N = 203.942 kg

So 20 N/ mm2 = 203.942 kg / cm2

RATIO IS 1:1.5:3

then volume is 1+1.5+3=5.5 and the total volume

for using mix=1.57 m3 then cement required=1/

5.5*1.57=0.285m3*1440=411 kg. (8+bag)

sandrequried=1.5/5.5*1.57=0.471m3

aggregaterequired=3/5.5*1.57=0.853m3

the standard volume of dry mix mortar=1.57.. U

can check it in IS code also. Then volume is

1+1.5+3=5.5 and the total volume for using

mix=1.57 m3 then cement required=1/

5.5*1.57=0.285m3*1440=411 kg.(8+bag)

sandrequried=1.5/5.5*1.57=0.471m3

aggregaterequired=3/5.5*1.57=0.853m3

the standard volume of dry mix mortar=1.57.. U

can check it in IS code also.
MATERIAL CALCULATION:

CEMENT IN BAGS
01. PCC 1:5:10 1440/5*0.45 129.60Kg 2.59

02. PCC 1:4:8(M 7.5) 1440/4*0.45 162.00Kg 3.24

03. PCC 1:2:4(M 15) 1440/2*0.45 324.00Kg 6.48

04. PCC 1:3:6(M 10) 1440/3*0.45 216.00Kg 4.32

05. RCC 1:2:4(M 15) 144/2*0.45 324.00Kg 6.48

06. RCC 1:1.5:3(M 20) 1440/1.5*0.45 32.00Kg

8.64

07. RCC 1:1:2(M 25) 370.00Kg 7.40

08. RCC M 30 410.00Kg 8.20

09. RCC M35 445.00Kg 8.90

10. RCC M40 480.00Kg 9.60

11. Damp Proof Course

CM1:3,20mm tk 1440/3*0.022 10.56Kg 0.21

12. 2″tk precast slab M15 324*0.05 16.20Kg 0.32

13. 3″tk precast slab M15 324*0.075 24.30Kg

0.49

14. GC Masonry CM 1:7 1440/7*0.34 70.00Kg

1.40

15. Brick Work CM 1:6 1440/6*0.25 60.00Kg 1.20

16. Brick Work CM 1:4, 115tk 1440/4*0.25*0.115

10.35Kg 0.21

17. Grano Flooring CC 1:1.5:3 1440/1.5*0.45*0.05

21.60Kg 0.43

18. Plastering CM 1:3, 12mm tk 1440/3*0.014

6.72Kg 0.13

19. Wall Plastering CM 1:4,

12mm tk 1440/4*0.014 5.00Kg 0.10

20. Laying Pressed Tiles Over

a CM 1:4, 20mm tk 1440/4*0.022 7.92Kg 0.16

21. Ceramic Tiles, Marble,

Granite, Caddapah Slab

CM 1:4, 20mm tk 1440/4*0.022 7.92Kg 0.16

22. Hollow Block Masonry

CM 1:6, 200mm tk/m¬2¬ 10.00Kg 0.20
SAND CALCULATION (CFT):
01. Any Concrete Work

(PCC, RCC) 0.45*35.315= 20.00

02. Damp Proof Course

CM `1:3, 20mm tk 1.00

03. 2″tk Precast slab M15 1.00

04. 3″tk Precast slab M15 1.50

05. SS Masonry in CM 1:7 15.00

06. Brick Work in CM 1:6 15.00

07. Brick Work in CM 1:4,115mm tk 2.00

08. Grano Flooring in CC 1:1.5:3 1.00

09. Plastering in CM 1:3, 12mm tk 1.00

10. Wall Plastering CM 1:4, 12mm tk 1.00

11. Laying Pressed Tiles over a CM 1:4, 20mm tk

1.00

12. Ceramic Tiles, Marble, Granite, Cuddapah slab

CM 1:4, 20mm tk 1.00
METAL CALCULATION:
01. Any Concrete Work 32.00 cft

02. Grano Flooring in CC 1:1.5:3, 50mm tk 1.60

cft

03. Grano Flooring in CC 1:1.5:3, 75mm tk 2.40

cft

04. Grano Flooring in CC 1:1.5:3, 100mm tk 3.20

cft

05. Bricks/cum 450.00 Nos

06. Size Stone/ cum 90.00 Nos

07. Rough Stone 10.00 cft

08. Bond Stone/ cum 10.00 Nos

09. Cement Paint/100 Sft 2.00 Kg

10. White Cement/100 Sft 2.00 Kg

11. Janathacem/100 Sft 1.50 Kg

12. Enamel Paint/100 Sft – 2 Coats 1.25 Litre

13. Wall Putty/100 Sft 10.00 Kg

14. Plaster of Paris/100 Sft 25.00 Kg

15. Distember/100 Sft 2.00 Kg

16. Cement Primer 0.60 Litre

0.40 Litre

17. Weathering Course

Lime 12.50 Kg

Brick bats 32.00 Kg

18. Providing Sand Gravel Mix- Cum

Sand 20.00 Cft

Gravel 40.00 Cft

19.WBM – 75mm tk – 1st Layer – 10 Sqm

Metel(60-40 mm) 35.00 Cft

Gravel 10.00 Cft

20. Pressed Tiles – Sqm 20.00 Nos

21. Hollow Block – 200mm tk 14.00 Nos
CONVERSION TABLE:

01. 1 RM 3.28 Rft

02. 1 Sqm 10.76 Sft

03. 1 Cum 35.32 Cft

04. 1 Inch 2.54 cm

05. 1 sft 0.09Sqm

06. 1 Acre 0.04 Hectare

07. 1 Hectare 2.47 Acres

08. 1 Cft 0.028 Cum

09. 1 Feet 12.00 Inch

10. 1 Feet 0.305 M

11. 1 Cum 1000.00 Litre
UNIT WEIGHT:

01. Concrete 25 kN/m3

02. Brick 19 kN/m3

03. Steel 7850 Kg/m3

04. Water 1000 Lt/m3

05. Cement 1440 Kg/m3

06. 1Gallon 4.81 Litres

07. Link 8″ = 200mm

08. 1 Hectare 2.471 acr(10000m2)

09. 1 Acr 4046.82m2 = 100 cent
DEVELOPMENT LENGTH:

01. Compression 38d

02. Tension 47 & 60d

03. 1 Cent 435.60 Sft

04. 1 Meter 3.2808 ft

05. 1 M2 10.76 ft2

06. 1 Feet 0.3048m

07. 1 KN 100Kg

08. 1kN 1000N

09. 1 Ton 1000Kg = 10,000 N = 10 kN

10. 1 kG 9.81N
M5=2.54Bg/m3, M7.5=3.18Bg/m3, M10=4.32Bg/

m3,

M20=8.64Bg/m3, M25=12.9 Bg/m3,

M40=500+100Kg/m3
1m3 Conrete = 0.9 m3 Jelly + 0.55 m3 Sand +

0.225 m3
BRICK:

Weight = 3.17 – 3.80 Kg

Water absorption 12 to 15%

Compressive strength = 36Kn/cm2

230mm Wall/m3 = 460 Bricks + 20Cft Sand +

66Kg Cement
SSM 1:7/m3 = Slize 95 + Soiling 8 Cft +60.5 Kg

Current = 1000 Watts = 1 Unit, 25Watt*40Hr = 1

Unit

Sunshade = 65mm – 0.56 bag/m2,

= 90mm – 0.78