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.

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.

In this post, I will describe what a Health and Safety File looks like and how to set one up.

A Health and Safety File shall include the following documentation:

• A Health and Safety Policy
• A Health and Safety Plan
• Certification of Employees
• Certification of Equipment
• Laws and Legal Notices

The documentation shall be organized in a lever arch file with the above mentioned tabs.

Health and Safety Policy
This policy shall include the Health and Safety beliefs of the company, duly signed by the company directors.

Health and Safety Plan

• Include Health and Safety Plan
• Include emergency route to hospital

Employees
Include all the documentation to prove that the employees have been suitably trained, are well experienced and were given the required Personal Protective Equipment. This can be done by attaching:

• Nominate employee representative and first aider on site.
• A certificate of the first wider shall also be inserted.
• Certificates of attendance of employees to H&S courses,
• Listing Experience of employees,
• Medical certificates of employees where applicable
• A signed list by each employee who was given the Personal Protective Equipment,
• List of toolbox talks duly signed by the employees receiving talk.

Equipment

• Include List of all equipment on site.
• Include VRT tests and copy of log book of each vehicle
• Include maintenance schedule of equipment
• Include engineer certificates of cranes and other equipment
• Include brochures of equipment on site
• Include certificates of chains and slings.

Method Statements

• Include method statements and risk assessment (MSRA) for the main works and insert in file.

Laws and Legal Notices

• Print the following laws and legal notices and insert in the Laws and Legal Notices Tab. These can come in handy on site.

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.

Each project can have several ITRB’s for different stages. For example, you can have an ITRB for:

• Laying of services,
• Laying of concrete
• Asphalt works
• Laying of unbound materials
• Precasting of precast elements etc.

The ITRB consists of several copies of a simple template collated together in a binded folder.

The template is divided into two parts:
A) Contractor’s Request

• The contractor first writes the request reference number sequentially.
• Then he describes the request – for example “Visual Inspection on Type 1″,
• Contractor writes the date the request was made and when the task will be ready for instruction.
• The date when the contractors Quality Assurance team has been notified is also listed.

B) Supervisor’s comments

• When the task is ready for inspection, the supervisor will carry out a site inspection
• He shall write his comments in the ITRB.
• If the task is executed satisfactorily then the works may proceed.
• If the task is not up to standard, remedial works are to be carried out and a new inspection request has to be prepared by the contractor.
• If the request listed in the ITRB makes reference to tests carried out on site, then these test results shall be attached to the ITRB and they shall have the same request number they relate to.

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.

2. LEVELS

Use the String Method to check the levels at 3 points along the carriageway.

Take surveyed points every 10m,
A) On the gutter of both sides of the carriage way,
B) On the underlying material on the left, middle and right side of the carriage way,

Compare the surveyed points on the gutter with the:
A) proposed levels in the construction drawings.
B) existing surveyed levels on the underlying material and make sure that there is enough space for all the asphalt layers. I am attaching a sample spreadsheet to help you with this task.

If there is not enough space for all the asphalt layers then the existing unbound material has to be scarified and re-laid to the appropriate levels accordingly.

If the existing underlying material is found to be too low, do not add layers less than 150mm thick above it to correct levels. Layers thinner than 150mm will form ‘biscuit’ layers which are to be avoided. The problem can be resolved by first scarifying the existing unbound material to a depth where the new layer and the scarified layer are 150mm thick.

3. VISUAL INSPECTION

The minimum thickness of Type 1 layers shall be 150mm. Any layer smaller than that will create thin 'biscuit layers' which have to be removed prior to asphalt laying.

Check that:

• All unbound material next to manholes is properly compacted,
• All loose material is removed
• There is no debris such as wood, plastics in the unbound material. Remove any such materials.
• There are no ‘biscuit’ layers. Remove all such layers.
• The unbound surface is swept and free from dust.
• The side of the gutter is coated with Tar.

New Road Construction Concepts

This is just a short post highlighting EU’s vision for 2040. It attempts to build reliable, green, safe, smart, and human infrastructure and the vision is outlined in the document commonly known as NR2C. Read more by following the link New Roads Construction Concepts.

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.

Step 1 : Determine the Size of the Manhole

A manhole is a link between an underground service and the surface above it, through which the service can be accessed and maintained.

The size of a manhole depends on:

• the pipe diameter.
• the depth between the road level and the crown of the pipe.

Shallow manholes come in two sizes:

• 900x700mm, known as Manhole Type A which is used for small diameter pipes up to 500mm diameter.
• 1000x1050mm, known as Manhole Type B, for pipes ranging from 500mm up to 900mm diameter.

Step 2: Determine the Type of Construction

Shallow manholes can be constructed in block work, in-situ concrete, pre-cast concrete chambers, corrugated galvanised steel chambers. In this post we will be showing manholes constructed in blockwork and in-situ concrete.

Step 3: Excavate Terrain for Manhole Structure

After determining the minimum dimensions, excavate terrain for manhole and allow an extra 230mm on either side of the pipe for the manhole walls. The depth of excavation shall be a minimum of 150mm below invert level to allow for manhole foundations.

If the surface on which the foundation shall be placed is rock, then the surface has enough bearing capacity to construct the manhole structure. The surface shall be swept from debris and large stones.

If the surface is unbound material, then the surface shall be wetted and compacted using hand compactors.

Step 4: Lay reinforced concrete foundation

Lay A393 reinforcement mesh top and bottom as shown in the diagram. Use concrete spacers to minimum of 40mm cover around the mesh.

When you are ready to lay the concrete, wet the surface and pour a minimum of 150mm thick layer of C20 concrete (also known as ST4 concrete), up to the invert level of the pipe.

Type A Manhole

Step 5: Constructing the concrete walls

When the foundation concrete has set, lower the steel formwork into position. Make sure that there is a space of 230mm between the steel formwork and the exposed rocky face to ensure that the manhole walls are thick enough. Use an A393 mesh around the steel formwork ensuring that there is at least 40mm cover and adequate lapping, shaped into a rectangular shape. Cast the C20 concrete between the steel form and the exposed rock, up to road formation level and vibrate the concrete.

Type B manhole

Step 6: Formation of benching

C10 concrete shall be used to form the benching next to the sides of an open channel as per above-drawings.

Step 7: Roofing the manhole

The manhole shall then be roofed using a pre-cast concrete slab, consisting of 180mm thick C20 concrete with A393 mesh top and bottom, having an opening of 600x600mm.

The orientation of the manhole roof shall be in line with road features such as kerbs etc.

Other Tips:

• Avoid manhole covers from asphalted areas.
• Sometimes it is not possible to construct manhole covers out of asphalted areas.
• In this circumstance, refrain from installing manhole covers in the wheel path.
• They shall be installed next to the kerb, in the middle of the lane or on the centre line.

Step 7: Selection of manhole cover

Classification of Manholes as per EN124

Manhole covers shall be specified according to European Standard EN124, which classifies manhole covers into 6 groups, according to their intended use ranging from class A15 intended to be used in pedestrian areas only to F900 which are intended to be used in freeports and airports. Class A15 manhole covers can withstand 15kN while F900 manhole covers can withstand 900kN.

• Group 1 – A15, for light loads
• Group 2 – B125
• Group 3 – C250
• Group 4 – D400
• Group 5 – E600
• Group 6 – F900, for heavy loads

Manhole covers should be properly installed as per manufacturer’s recommendations to ensure that they perform satisfactorily. For more details you can follow the link below:

• Proper installation of manhole covers.

Shifou Mountains - Click on the image for the complete set of photographs.

I wonder if there are any Health & Safety Authorities in China. Who is going to check if these employees have all the required harnesses and minimum Personal Protective Equipment, while they are constructing a footpath along the vertiginous slopes in Shifou Mountains? I do not know if they have the minimum PPE but they sure must have nerves of steel.

AJ McCormack’s authoritative website offers in depth, well researched information and clear diagrams describing the proper installation of concrete block paving. Topics include:

• Selection of concrete paving blocks
• Setting out
• How to lay blocks in a particular pattern
• How to lay concrete blocks at edges.
• Installation of recess trays

Should you know of any other websites about concrete paving blocks, please share it by writing the link in the comments below.

Valletta Road, Zurrieq

Brief Description

Client: Transport Malta

Supervisor: Edwin Mintoff & Associates

This project was started in January 2010 and had to be completed within 36 weeks.

The Valletta Road Zurrieq Reconstruction project consisted in the laying of new services such as sewer mains, potable water mains, 6 way duct routes for telecommunication cables, Enemalta cables and a storm water network. The road was completely rebuilt. It includes reinforced C30 concrete hard shoulders on both sides. Crash barriers and new street lighting were also installed. A reservoir was built for storm water harvesting.

The project was completed on budget and ahead of schedule.

Newsclips

05.02.2010 Valletta Road to be completed by August 2010

27.07.2010 Valletta Road re-opened to traffic within budget and ahead of schedule

29.07.2010 The Valletta Road Project is completed to high standards and ahead of schedule