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Measurement of surface roughness by surface irregularity test
#3mlongstraight edgemethod
#surfaceirregularitytest


The 3m Straight Edge Method is a simple and widely used technique for measuring surface irregularities. Here's a step-by-step guide:

Equipment Needed
1. 3m long straight edge (aluminum or steel)
2. Wedges or shims
3. Measuring tape or ruler
4. Level (optional)

Test Procedure
1. *Place the straight edge*: Position the 3m straight edge along the surface, perpendicular to the direction of travel.
2. *Ensure levelness*: Check that the straight edge is level, using a level if necessary.
3. *Measure the gap*: Measure the gap between the straight edge and the surface at the midpoint and at 1m intervals along the length of the straight edge.
4. *Record the readings*: Record the measurements in millimeters or inches.
5. *Calculate the irregularity*: Calculate the surface irregularity index (SII) or international roughness index (IRI) using the measured values.

Acceptance Criteria
The acceptance criteria vary depending on the project specifications, but typical limits are:

For highways: 3-5 mm
For airport runways: 2-3 mm
For urban roads: 5-10 mm

Advantages
1. Simple and inexpensive
2. Quick to perform
3. Provides a good indication of surface irregularity

Limitations
1. Limited accuracy for complex surfaces
2. May not detect small-scale irregularities
#civilworldofficial
#pqcwork
Measuring the surface roughness of Pavement Quality Concrete (PQC) is crucial to ensure a smooth and safe riding surface. Here are the common methods:

Methods
1. *Straight Edge Method*: A 3m long straight edge is placed on the surface, and the gap between the edge and surface is measured.
2. *Profilograph Method*: A profilograph is a device that measures surface roughness by tracing the surface profile.
3. *Laser Profilometer Method*: A laser profilometer uses laser technology to create a high-resolution profile of the surface.
4. *Sand Patch Method*: This method measures the texture depth of the surface by applying a known volume of sand to the surface.

Parameters Measured
1. *International Roughness Index (IRI)*: Measures the roughness of the surface.
2. *Ride Number (RN)*: Measures the smoothness of the surface.
3. *Mean Profile Depth (MPD)*: Measures the average depth of the surface profile.
4. *Texture Depth (TD)*: Measures the depth of the surface texture.

Acceptance Criteria
The acceptance criteria vary depending on the project specifications, but typical limits are:

IRI: 1.5-2.5 m/km
RN: 4-6
MPD: 0.5-1.5 mm
TD: 0.5-1.5 mm

Importance
Measuring PQC surface roughness is essential to:

1. Ensure a smooth and safe riding surface.
2. Prevent accidents caused by uneven surfaces.
3. Reduce vehicle wear and tear.
4. Extend the lifespan of the pavement.
#constructionmethodologyofcivilwork