Posted: May 21st, 2012 | Filed under: 0900 Road Pavements (Bituminous Materials) | No Comments »
Switch OFF vibration in good time before reversing.
Pre-roll without vibration if there is a low pre-compaction by the paver.
Select vibrator frequency on asphalt mix type and laying thickness in line with recommendations from the roller manufacturer. Compact surface layers with high frequency rates. Thick layers from 8cm onwards shall be vibrated with low frequency rates.
DO NOT use excessive speed as you might create the washboarding effect.
Use static compaction when moving downhill. Use vibration only when moving uphill.
When the asphalt temperatures reach 100 degrees celsius switch off vibration to avoid the risk of crushing the aggregates, and will eventually lead to cracks. For the same reason, compact thin asphalt layers only with low vibration effects and few passes or better still entirely without vibration.
With dense mixtures, too much compaction at high temperatures may lead to bitumen being pushed to the surface layer. Consequently, the skid resistance of the road surface will be lowered.
Posted: May 20th, 2012 | Filed under: 0900 Road Pavements (Bituminous Materials), Quality Assurance | No Comments »
1. Start compaction as early as possible.
2. Drive with the driven drum towards the paver to avoid the formation of ripples and cracks. Combination rollers should be used with the rubber tyres towards the paver.
3. To avoid mix material sticking, drums and tyres must be lightly sprayed with water. They should be moist but not wet.
4. DO NOT use vibration when the machine is at a standstill. This will avoid the formation of waves.
5. Drive smoothly and do not change direction in jerky movements. The use of an automatic speed control system can improve the rolling quality.
6. Switch the vibration on only when the machine is moving. Switch the vibration off in good time before reversing.
7. If the road is cambered start compaction from the lower edge and overlap each pass towards the higher edge.
8. Steer and offset the machine only on compacted material to avoid shoving of asphalt.
9. Never stop the roller on hot mix material since the machine will probably cause deformation of the layer.
10. ALWAYS park the machine at an oblique angle to the direction of the work so that any marks can be smoothed out later.
Posted: February 13th, 2012 | Filed under: Quality Assurance, TM Specifications for Road Works | No Comments »
A sample page from an ITRB
Quality Assurance plays a very important role in construction works. It has to be carried out and the process must be well documented. The QA process is documented in an INSPECTION TEST REQUEST BOOK commonly known as an ITRB. Read the rest of this entry »
Posted: January 29th, 2012 | Filed under: 0600 Earthworks, 0700 Road Pavements (General), 0800 Road Pavements (Unbound Materials), Quality Assurance | No Comments »
In this post we will discuss the three main points to be checked prior to asphalting works to make sure that the underlying materials are up to standard.
1. PLATE BEARING TESTS
Plate bearing tests shall be carried out on the compacted unbound layer as per testing frequency required by the contracting authority. Make sure that:
is greater than the required bearing capacity Ev2 stipulated in the road structure catalog (usually should be greater than 180n/mm2).
the ratio between Ev2 and Ev1 is less than 2.2.
Read the rest of this entry »
Posted: September 8th, 2011 | Filed under: 0500 Drainage and Service Ducts, TM Specifications for Road Works | No Comments »
Most underground services need to be accessed to carry out repair and maintenance works. They can be accessed through manholes, which consist of a vertical shaft allowing a person to get into a chamber below ground level. The type and size of manhole depends on the type of action required for repair and maintenance works to the service. Each entity has its own requirements for its own manhole.
Manholes can be divided into two categories:
- Series 1500 Manholes for motorway communication ducts.
- Series 500 Manholes for sewer and storm water networks, including catch pits, inspection chambers and draw pits.
In this post, the latter manhole will be described.
Posted: August 20th, 2011 | Filed under: 1100 Kerbs, Footways and Paved Areas, Links | No Comments »
- The proper laying of concrete block paving is clearly explained in AJ McCormack’s website.
AJ McCormack’s authoritative website offers in depth, well researched information and clear diagrams describing the proper installation of concrete block paving. Topics include:
Should you know of any other websites about concrete paving blocks, please share it by writing the link in the comments below.
