* Guidelines to Site Engineers *



Guidelines for Civil Site Engineers

Role and Responsibilities of a Civil Site Engineer:

Roles and responsibilities of a civil site engineer depends on the nature of construction works in a project and involves various activities such as quality control and reporting.

As the activities carried out in a construction industry is highly dynamic in nature, different decisions and actions have to be carried out unexpectedly. These sudden actions are mostly carried out by the site in charge or the civil site engineer at construction site.

This means the roles and responsibilities of a civil site engineer is not specific for every construction site. These changes based on the activities and site conditions of the project. But in brief, the site engineer must possess certain basic roles and responsibilities for the execution and completion of the project.

The site engineer should possess basic knowledge about the practical construction procedures in site, along with the details of how they are planned. This idea of planning and coordination will help him to have proper execution of the activities in the site with desired performance.

A site engineer is very essential for a construction project. The responsibilities of a site engineer are wide as he must provide sufficient advice and supervision when there are any technical issues, or for proper management and for the preparation of day to day reports of the construction works.

The responsibilities that is put on a site engineer in construction is mentioned briefly in below:

1. Construction Site Responsibilities

The site engineer is the person who spends most of his time at the construction site compared with other managers or designers. Site engineers are updated daily about the coming day’s design and activities based on which he implements them at site.

The top members of the construction organization get a clear picture about the daily activities happening at the site through the site engineer.

2. Travelling

The site engineers are supposed to move from one site to another (based on the size of the project or number of projects) for any special needs. He must also be required to reach with the procurement of resources to get the materials as per the correct specifications if any discrepancies happen.

This means every sector of activities say its design, materials or execution, the site engineer has the role of advice.

3. Technical Activities

Site activities like establishment of the level and the survey control, which is required for the control of contracts must be performed by site engineer in required conditions. The works have to be set out as per the contract drawings. This requires checks at regular basis on the construction site.

The records maintained have to be accurate and they have to satisfy with the organizational and the legal requirements.

The site engineer has to face any unexpected difficulties raised from the technical side at any point of time. He must study the problem and resolve it in the most efficient manner as possible.

4. Preparation of Reports and Schedules

The site engineer is the one who have to ensure that the site have adequate resources to complete the tasks. This is conducted by having procurement schedules for the jobs carried out and liaise with the procurement department regarding the same.

A report on the future works to be carried out at site are prepared and produced by site engineers two weeks ahead. This is carried out in conjunction with the site agent.

The site engineer is responsible for keeping site diaries and the respective sheets for allocation.

5. Site Engineer for Health and Safety

For highly dangerous work site, the site engineer will take up the role of safety engineer. He has to ensure that the work carried out by the workers and other related activities are as per the safety regulation of the respective state or area.

Every construction organization must possess a safe working culture and practice. Its implementation and practice of following is supervised by the site engineers. There may be other safety, health officers for the organization, but ensuring safety is a common need.

Other responsibilities are to undergo construction activities that will promote the environmental compliance. Each work has to be carried out safely within the deadline.

6. Quality Assurance by Site Engineer

As we know, quality is a parameter that have to be kept in practice from the initial stage of planning to the end of the project. The major issues with design and documentation can be corrected during the construction by the site engineer based on advice from the structural engineers.

Any undesirable activities in construction brings high loss of quality and money. The site engineer assures quality by the following means:

  • Promoting the best construction practices
  • Undergo activities and practices that comply with the procedures of the company and the specification.
  • Assures the work is completed and delivered without any defect and delay
  • One must highlight value engineering opportunities

7. Communication and leadership duties

As the site engineer have to know the technical details from the above levels and make it in practice in the site, he must be efficient enough to coordinate the information that is communicated. He must take up the detail from the higher levels accurately and pass them to the below contractors, supervisors or labor workers. It not how efficiently you as a site engineer understand the idea, but it’s on how you convey it to your sub-workers. This will reflect to have the need for leadership quality to convey and make the workers do the work.

SAFETY IN CONSTRUCTION:

Workers / employees‘ life safety is valuable asset. Work force can be protected and also workers compensation cost can be reduced by improving safety and preventing accidents. The code summarizes the basic safety and health requirement for public works.

Safety practices and regulation

Proper safety practices and regulation will help in avoiding or at least in reducing accidents and fatalities. Hazards such as adverse site conditions, exposure to excess heat & cold, electricity, dust, deafening sound, booms and arms of machines are to be studied and analyzed before providing programme to operators of plants and other personnel at site. Even visitors should follow these safety programmes. IS codes for safety & health shall be followed during safety practices and regulation.

Safety Programme:

Safety programme is an integral part of the construction operations. As effective safety programme must instill a sense of safety consciousness in every worker from top to bottom. Protecting equipments must be provided to workers while performing hazardous jobs. The following are normally provided depending on type and nature of work.

  • Helmet
  • Gum boots
  • Gloves
  • Goggles
  • Apron
  • Safety saddles
  • Portable lights
  • Fire extinguishers
  • Safety belts
  • Gas masks
  • Oxygen or air breathing apparatus
  • Face mask
  • Ear protector.

Accident reporting:

Any accident that interrupts or interferes with orderly progress of the activity causing personal injury (either fatal or non fatal) or property damage must be properly investigated by the safety officer / qualified person and is to be submitted with the following details by the field engineers and / or Assistant Executive Engineers.

Name of employee injured

Identifying data such as date, time, Department, name of supervisor and operation being performed

Description of accident, injury, first aid provided, shifting to the hospital

Description of the unsafe condition that caused the accident

Description of the unsafe act that caused the accident

Recommendations to prevent reoccurrence of such accident in future Such accident reports are generally used for future safety measures and are very helpful in reducing the number of similar accidents.

Safety tips in construction:

There are a number of safety lacunae which need rectification to minimize health hazards in construction industry.

The contractor should ensure that all the personnel engaged in construction activity are well trained about safety.

Before starting of the day of work, the workers should be apprised about the possible hazards and risks involved and procedure to overcome such hazards.

The workers involved at site shall be re-trained after every successive project.

The contractor should ensure that all his personnel are insured as per prevailing Government rules.

The construction site should be fully equipped with all the required safety equipment’s including first aid facility.

Over working: The illiterate workers engaged in construction industry should be educated about their working time and their wages. Overtime shall be avoided as far as possible.

The contractor should ensure that proper communication system at the plant site, office premises and at work site and also telephone numbers of emergency, nearest hospital or clinic, ambulance, police, fire force and other required contract numbers.

Safety measures by the contractors

The Bureau of Indian standards stipulate several codes for safety management, material handling, storage, safety precautions health‘s etc. The contractors are required to follow the IS codes for safety during constructions which are listed below are prominently displayed.

Safety Management Codes in construction work IS

3696 (I):1996 for scaffoldings: Revised 1987 IS

3696 (II):1966 for Ladders: Revised 1991

IS 3764:1966 for Excavation works: Revised 1992

IS 4130:1976 for Demolition of Buildings: Revised 1991

IS 7205:1974 for erection of steel structures

IS 5121:1969 for piling and other deep structures

IS 5916:1970 for construction involving hot bituminous material

IS 8969:1978 for erection of concrete framed structure

Material Handling, Storage and safety precautions:

IS 7969:1975 Satety Code for Handling

IS 4082:1977 Stacking and Storage

IS 4081:1986 (R2010) Safety code for Blasting and Related Drilling operations

IS: 818:1968 (Ref – 03) Safety and health requirements – in Electric and Gas welding and cutting operations

IS: 6922:1973 criteria for safety and design of structures – subject to underground blasts

IS: 7293:1974– safety code for working with construction machinery.

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Following are few general points to remember for civil site engineers to make the construction work easier while maintaining quality of construction:

  • Lapping is not allowed for the bars having diameters more than 36 mm.
  • Chair spacing maximum spacing is 1.00 m (or) 1 No per 1m2.
  • For dowels rod minimum of 12 mm diameter should be used.
  • Chairs minimum of 12 mm diameter bars to be used.
  • Longitudinal reinforcement not less than 0.8% and more than 6% of gross C/S.
  • Minimum bars for square column is 4 No’s and 6 No’s for circular column.
  • Main bars in the slabs shall not be less than 8 mm (HYSD) or 10 mm (Plain bars) and the distributors not less than 8 mm and not more than 1/8 of slab thickness.
  • Minimum thickness of slab is 125 mm.
  • Dimension tolerance for cubes + 2 mm.
  • Free fall of concrete is allowed maximum to 1.50m.
  • Lap slices not be used for bar larger than 36 mm.
  • Water absorption of bricks should not be more than 15 %.
  • PH value of the water should not be less than 6.
  • Compressive strength of Bricks is 3.5 N / mm2.
  • In steel reinforcement binding wire required is 8 kg per MT.
  • In soil filling as per IS code, 3 samples should be taken for core cutting test for every 100m2.

Density of Materials:

Material Density
Bricks 1600 – 1920 kg/m3
Concrete block 1920 kg/ m3
Reinforced concrete 2310 – 2700 kg/ m3
Curing time of RCC Members for different types of cement:
  • Super Sulphate cement: 7 days
  • Ordinary Portland cement OPC: 10 days
  • Minerals & Admixture added cement: 14 days

De-Shuttering time of different RCC Members

RCC Member De-shuttering time
For columns, walls, vertical form works 16-24 hrs.
Soffit formwork to slabs 3 days (props to be refixed after removal)
Soffit to beams props 7 days (props to refixed after removal)
Beams spanning upto 4.5m 7 days
Beams spanning over 4.5m 14 days
Arches spanning up to 6m 14 days
Arches spanning up to 6m 21 days
Cube samples required for different quantity of concrete:
Quantity of Concrete No. of cubes required
1 – 5 m3 1 No’s
6 - 15 m3 2 No’s
16 – 30 m3 3 No’s
31 – 50 m3 4 No’s
Above 50 m3 4 + 1 No’s of addition of each 50 m3

 Recommended Valves of Slumps for Different Concrete Mixes

Type of Concrete Slump Range In mm
Heavy mass construction 25-50
pavements 20-30
Bridge deck 25-75
Beams and slabs 50-100
Columns, retaining walls and thin vertical members etc. 75-150
vibrated concrete 12-25

CONCRETE MIX DESIGN AS PER
IS 10262:2009

Data for Mix Proportioning

The following data are required for mix proportioning of a particular grade of concrete:

  1. Grade designation
  2. Type of cement
  3. Maximum nominal size of aggregate
  4. Minimum cement content
  5.  Maximum water-cement ratio
  6. Workability
  7.  Exposure conditions
  8.  Maximum temperature of concrete at the time of placing
  9.  Method of transporting and placing
  10.  Early age strength requirements, if required
  11.  Type of aggregate
  12.  Maximum cement content
  13.  Whether an ad mixture shall or shall not be used and the type of admixture and the condition of use        

Step 1: Determination of  Target mean Strength of concrete

ft= fck+1.65.s

Where,  

ft= target mean compressive strength at 28 days in N/mm2

fck = Characteristic compressive  strength of concrete at 28 days  in N/mm2

S = standard deviation in  N/mm2 ( refer table 1 given below)

Table 1 : Assumed Standard Deviation 

Sl No Grade of Concrete Assumed Standard Deviation (N/mm2)
1 M 10 3.5
2 M 15
3 M 20 4.0
4 M 25
5 M 30 5.0
6 M 35
7 M 40
8 M 45
9 M 50
10 M 55

Choose  w/c ratio against max w/c ratio for the requirement of durability. (Refer Table 2  and Table 3 given below).

Step II : Selection of  Water Cement (w/c)  Ratio

Table 2 : Durability Criteria As per IS 456: 2000 ( For Aggregates of 20 mm nominal maximum size)

Exposure Plain Concrete Reinforced Concrete
Min Cement in Kg/m3 Max w/c Min Grade Min Cement in Kg/m3 Max w/c Min Grade
Mild 220 0.60 -- 300 0.55 M 20
Moderate 240 0.60 M 15 300 0.50 M 25
Severe 250 0.50 M 20 320 0.45 M 30
Very Severe 260 0.45 M 20 340 0.45 M 35
Extreme 280 0.40 M 25 360 0.40 M 40

Table 3 : Adjustment to minimum cement content for aggregates other than 20 mm nominal max size aggregates As per IS 456: 2000

Sl No Nominal Max Aggregate Adjustment to minimum cement content in Table 2 in Kg/m3
1 10 +40
2 20 0
3 40 -30

 Step III:  Selection of water content

The quantity of maximum mixing water per unit volume of concrete can be determined from table 4 and table 5 given below.

Table 4: Maximum Water content per cubic metre  of concrete for nominal maximum size of aggregate. ( For angular coarse aggregate and slump range 25-50 mm )

Sl No

Nominal Maximum size of Aggregate (in mm)

Maximum Water Content  (in Kg)

1

10

208

2

20

186

3

40

165

Table 5:  Correction to values in table 4 for other site conditions

Sl No

Condition

Correction

1

Sub – Angular Aggregates

-10 kg

2

Gravel+ Crushed Aggregates

-20 kg

3

Rounded Gravel

-25 kg

4

For every slump increase of 25 mm

+ 3 %

5

Use of Water reducing Admixture

-5 to - 10 %

6

Use of superplasticzing Admixtures

-20 %

 

Step 4 : Calculation of Cementitious Material Content

Calculate the cement content from w/c ratio and final water content arrived after adjustment. Check the cement content calculated against the minimum cement content specified in table 2. The greater of the two values shall be adopted.

Step 5 :  Proportion of volume of coarse aggregate

For w/c ratio of 0.5 , table 6 is to be used .

Table 6:  Volume of Coarse  Aggregate per unit volume of total aggregate for different zones of Fine Aggregate .

Sl No

 

Nominal Maximum size of Aggregate (mm)

 

Volume of coarse aggregate per unit volume of Total Aggregate for Different Zones of Fine Aggregate

Zone IV

Zone III

Zone II

Zone I

i)

10

0.50

0.48

0.46

0.44

ii)

20

0.66

0.64

0.62

0.60

iii)

40

0.75

0.73

0.71

0.69

Correction in Coarse aggregates values:

  • For every  +0.05 change in w/c ratio : -0.01
  • For Every -0.05 change in w/c ratio : +0.01
  • For pumpable concrete mix : - 10 %

Step 6:  Final Mix Calculations

Volume of concrete = 1 m3

                                                             Mass of water
Volume of cement =--------------------------------------
                                              (Specific gravity of cement x 1000 )
     

                                                             Mass of water
Volume of water =--------------------------------------
                                             (Specific gravity of water x 1000 )
     

                                                                           Mass of chemical admixture
Volume of chemical admixture =--------------------------------------
                                                                        (Specific gravity of admixture x 1000 )
     

Volume of all in aggregates = [a- (b+c+d)]

Mass of coarse aggregates = (e x Volume of Coarse aggregate x  Specific gravity of coarse aggregate x 1000)

Mass of fine aggregate = (e x Volume of fine aggregate x Specific gravity of fine aggregate x 1000)

Following table shows maximum bearing capacity values of different types of soils:

Types of Soil Bearing Capacity (Kg/m2) Bearing Capacity (kN/m2)
Soft, wet clay or muddy clay 5000 50
Soft clay 10000 100
Fine, loose and dry sand 10000 100
Black cotton soil 15000 150
Moist clay and sand clay Mixture 15000 150
Loose gravel 25000 250
Medium clay 25000 250
Medium, compact and dry sand 25000 250
Compact clay 45000 450
Compact sand 45000 450
Compact gravel 45000 450
Soft rocks 45000 450
Laminated rock such as sand stone & Lime stone 165000 1650
Hard rocks such as granite, diorite, trap 330000 3300

Bearing capacity of soil is the maximum load per unit area. This is the ultimate bearing capacity of soil shown in table. Dividing the ultimate soil bearing capacity by a safety factor we get the maximum safe bearing capacity of soil for design of foundations.


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