Methodology For Laying of Mastic Asphalt (12 mm thick) on Bridge Deck.

Laying of Mastic Asphalt (12mm thick) on Bridge Deck.

   1.1      General

     1.  Objective of the Method Statement:

The purpose of laying of Mastic Asphalt is to prepare the Bridge decks for impermeable surfacing.

    2.   Scope of the Method of Statement:

This work consists of laying in a single layer of 12 mm thick homogeneous mixture to yield a plastic and voidless mass.

1.2 Temporary Works

Road diversion, drainage diversion etc. shall be done as per site requirement, creating least interference to the flow of traffic.

   1.3  Surveys

As paving area is confined the levels of the Mastic Asphalt only to be checked and controlled before and during the laying process.

   1.4      Utilities

Not Applicable.

1.5 Traffic Arrangements and Control

During the process of laying Mastic Asphalt the traffic will not be opened as already the existing bridge is used for the traffic. Anyhow our construction vehicles, which are carrying mix, shall be effectively controlled by our safety stewards / supervisors.

1.6 Access

The carriageway is easily accessible by the team who are going to work as well as for the vehicles as necessary embankment shall be completed by the time.

1.7  Work Sequence Programme

1.8 Work Methodology

a)   The base on which the Mastic Asphalt is to be laid shall be prepared, shaped and conditioned to the specified levels, grade and cross fall   (camber) before the tackcoat application. The surface shall be carefully  prepared free from dust and Foreign material using broom.

a)  Binder may be heated to the temperature appropriate to the grade used and applied on the base at the rate of 3 kg/10sqm. Care shall be taken for providing a uniform unbroken spread of bitumen over the surface.

c)   The preparation of Mastic Asphalt consists of two stages.

1.       The first stage shall be mixing of filler and fine aggregates and then heating the mix to a temp. of 170⁰C to 200⁰C.

2.        The required quantity of bitumen shall be heated to 170 – 180⁰C and added to the heated aggregates.

3.       Initially the filler alone is to be heated in the cooker for an hour and then half the quantity of binder is added. After heating the mix for sometime, the fine aggregates and the balance binder are to be added and further cooked for about one hour.

4.        The second stage is incorporation of coarse aggregates and cooking the mixture for a total period of 3 hours. During cooking and mixing, care shall be taken to ensure that the contents in the cooker are at no time heated to a temp. exceeding 200⁰C.

d)   The Mastic Asphalt shall be deposited in the prepared surface where it is spread and level with the help of wooden rafters. The temp.of the mix at the time of laying shall be around 170⁰C. The thickness is ensured with the 12 mm wooden reapers. Physical joints are fused with the gas burners.

1.8.  Plant and Equipment:

Mastic cooking machine, burner for heating bitumen, sprayer for tack coat application and compressor for air cleaning surface.

1.9         Safety:

1        The mixing area will be safeguarded for minimum man entry as there are chances of fire mishaps surrounding to the mixture.

2       The Tack coat applicator shall be wearing hand glows and gumshoes to avoid the burning injury on legs and arms due to hot bitumen.

3        All the people working in the paving area shall be insisted for PPE application throughout the job period.

4          The people who are working with the heavy machinery shall be given pep talks about the safety awareness before starting the work.

The contractor will submit an Inspection request form to the Engineer at each relevant stage of works.

Element	Visual Inspection	Quality Control Testing	Survey Check
Checking of Mastic Asphalt surface / Bridge Deck surface
Tack Coat
Finished Work

1.10 Measurement for Payment:

Mastic Asphalt will be measured in terms of surface area of laying in Sq.m.