CIVIL ENGINEERING

24/02/2025

Meaning of steel grade

🔴B500DWR

📌B: (Bar)
It is the code for bars used in reinforced concrete and is usually not written on the bar
📌500:
Guarantee stress or yield stress of steel in megapascals and is the value considered in the design of structural elements with the exception of:
1) Longitudinal reinforcement in columns is reduced to 420 megapascals
2) Stem reinforcement (canes) in columns and beams is reduced to 420 megapascals
3) Reinforcement used to resist piercing shear in slabs is reduced to 350 megapascals.
📌D: (Ductility)
A degree of ductility (A, B, C, D) and D is the only degree acceptable for structures resistant to earthquake loads.
C is the ductility class is C, which means T/Y = 1.15

📌W: (Weld)
Means that the steel is allowed to be welded and if it is replaced by a dash (-) it means that the steel is not allowed to be welded and in this case it cannot be used in any structural element with welding joints such as axial tension elements (tie) or frame sections that resist moments in which overlapping joints are not allowed.
📌R: (Rough)
The type of bar in terms of texture has protrusions and is P in the case of smooth iron.

24/02/2025

Gernal Points Need to know on Site

1️⃣ Concrete Quality Control

• Workability Check (Slump Test) - ASTM C143 / IS 1199

Standard Slump Values:

Beams & Slabs: 75-100 mm

Columns & Footings: 150-175 mm

Pavements: 25-50 mm

• Compressive Strength Test (Cube Test) - ASTM C39 /IS 516

Required Strength at Different Ages:

7 Days: ~65% of 28-day strength

28 Days: 100% of design strength

• Curing Duration - ACI 308 / IS 456:2000

Minimum Curing Time:

Normal Concrete: 7 Days

High-Strength Concrete: 14 Days

In Hot Weather: Keep surfaces moist & prevent rapid evaporation

2️⃣ Reinforcement Inspection

• Concrete Cover for Reinforcement - ACI 318 / IS 456:2000

Standard Cover Requirements:

Slabs: 20-25 mm

Beams: 30-40 mm

Columns: 40-50 mm

Footings: 50-75 mm

• Lapping of Reinforcement Bars - IS 456:2000 / BS 8110

Standard Lap Lengths:

Tension Zone: 50D

Compression Zone: 40D

(D = Diameter of Bar)

3️⃣ Soil Compaction & Testing

• Field Density Test (FDT) - ASTM D1556 / IS 2720 (Part 28)

Compaction Standard:

Achieve 95%-100% of Maximum Dry Density (MDD)

Use sand cone or nuclear gauge method for accuracy

• Proctor Test - ASTM D698 / IS 2720 (Part 7)

Determine Optimum Moisture Content (OMC) to get maximum compaction

4️⃣ Brick & Aggregate Testing

• Silt Content in Fine Aggregate - IS 2386 (Part 2)

Silt Content Limit: ≤3% (for good-quality sand)

• Brick Water Absorption Test - ASTM C67 / IS 3495 (Part 2)

Limit: ≤20% by weight after 24-hour immersion

5️⃣ As per ACI 347-04 (Guide to Formwork for Concrete):

Vertical Formwork (Columns, Walls, Beams' Sides):

Can typically be removed after 12-24 hours, provided concrete gains sufficient strength to support itself.

Slabs (Props Left Underneath): Minimum 3-4 days

Slabs (Without Props): Minimum 7 days

Beams & Girders (With Props Underneath): Minimum 7 days

Beams & Girders (Without Props): Minimum 14 days

Footings & Retaining Walls: Minimum 1-3 days

22/02/2025

CIVIL ENGINEER Concrete interview questions and answers

Concrete

41. What to do if compressive strength is not meeting the required level?

NDT testing for concrete and if still not satisfactory then demolish.

42. What to do if slump is not meeting the required level?

Add an admixture to solve the problem. Keeping in view that the water ratio is not affected. otherwise cancelled.

43. What is NDT test of concrete?

NDT – Non Destructive Testing that include following tests
# Ultrasonic pulse velocity test
# Rebound hammer test
# Core cutting test

44. What are the different cover blocks used for protecting steel in RCC buildings?

# Pile cap 75-100mm
# Footing 50-70mm
# Column 40mm
# Beam 25mm
# Slabs 20mm-25mm
# Retaining wall 60mm
# Staircase 15mm

45. What is the minimum strength and thickness of blinding?

The minimum strength is 15N/mm2 and the thickness is 75mm respectively.

46. What are SRC and GGBS?

# SRC is sulphate-resisting cement concrete and is used in substructure areas. where sulphate attacks are high. (Ratio is 65% of SRC and 35% of OPC)

# GGBS is ground granulated blast furnace slag cement concrete also used in substructure area (Ratio is 70% of GGBS and 30% of OPC)

47. What are the factors affecting durability of concrete?
v Contaminated air
v Harsh weather
v Backfilling soil having through sulphates and chloride
v Contaminated water pe*******on through soil having harmful chemicals
v It means concrete have proper impermeability

48. Why waterproofing of the substructure is done?

To reduce sulphates and chloride attacks that reduce durability.

49. What are the types of waterproofing of concrete?

# Bitumen emulsion
# Bitumen emulsion plus sheet
# Epoxy-based emulsion
# Epoxy-based emulsion plus sheet
# Cementitious materials
# Inject materials in water tank & GRP lining in water tanks.

50. What is self-compacting concrete? or Self-Consolidating Concrete (SCC)

It needs no vibration and flows under its own weight. Its slumps are 550mm to 750mm. Its used in congested areas where we can’t place the vibrate easily.

18/02/2025

Pouring a concrete slab

17/02/2025

Marble cutting Machine

16/02/2025

Stunning view of beam steel 😜

14/02/2025

Project Management terminologies
E𝗻𝗴𝗶𝗻𝗲𝗲𝗿𝗶𝗻𝗴:

FS = Feasibility Study
FEED = Front End Engineering Design
DED = Detail Engineering Design
TRM = Technical Review Meeting
TBE = Technical Bid Evaluation
SDRL = Supplier Document Register List
IFR = Issued for Review
IFA = Issued for Approval
IFC = Issued for Construction
AFC = Approved for Construction
MDR = Manufacture Data Record
ITP = Inspection and Test Plan
TPI = Third Party Inspector
MRIR = Material Receiving Inspection Report
RFI = Request for Inspection
PIM = Pre-Inspection Meeting
NCR = Non-Conformance Report
IRN = Inspection Release Notes
SRN = Shipping Release Notes
PL = Packing List
MOM = Minutes of Meeting
TQ = Technical Query
FAT = Factory Acceptance Test
SAT = Site Acceptance Test
BOM = Bill of Materials
BOQ = Bill of Quantity
MTO = Material Take Off
MRO = Material Request Order
TOC = Top of Concrete
TOG = Top of Grouting
COG = Center of Gravity
TOS = Top of Support
BOP = Bottom of Pipe

𝗣𝗿𝗼𝗰𝘂𝗿𝗲𝗺𝗲𝗻𝘁:

PO = Purchase Order
WO = Work Order
RFP = Request for Proposal
RFQ = Request for Quotation
KOM = Kick Off Meeting
DP = Down Payment
CO = Change Order
FOB = Free on Board
FOT = Free on Truck
DAP = Delivered At Place
DDP = Delivered Duty Paid
ETD = Estimate Time Delivered
ETA = Estimate Time Arrived
LT = Lead Time
PB = Performance Bond
WB = Warranty Bond

𝗖𝗼𝗻𝘀𝘁𝗿𝘂𝗰𝘁𝗶𝗼𝗻:

CEP = Construction Ex*****on Plan
JSA = Job Safety Analysis
JS = Join Survey
CPM = Critical Path Method
MEP = Mechanical Electrical Plumbing
PPE = Personal Protective Equipment
QA = Quality Assurance
QC = Quality Control
WBS = Work Breakdown Structure
RBS = Risk Breakdown Structure
SOP = Standard Operational Procedure

13/02/2025

Grouting, in the context of construction, is a specialised process that involves injecting a fluid-like material into gaps, voids, or spaces within structures. Its purpose is to improve structural integrity, enhance load-bearing capacity, and provide stability to various elements of a construction project.

25/01/2025

22/01/2025

Some important notes on formwork.

20/05/2024

Rib slab beam reinforcement

19/05/2024

What's this ?
Comments

02/03/2024

Recommended slumps of concrete:
1 Concrete for road construction 20 to 40 mm
2 Beams and slabs 50 to 100 mm
3 Mass concrete 25 to 50 mm
4 Normal RCC works 80 to 150 mm

02/03/2024

Concrete template limit
10°C to 32°C