Double-Surface-dressing-双表处施工英文版.doc

Method Statement for Double Surface Dressing rev 04
UPGRADING PERAMIHO JCT TO MBINGA ROAD TO BITUMEN STANDARD
Method Statement for Double Surface Dressing
A. Personnel:
Team leader 1 (Wang Shizheng)
Mr. Zhang will be responsible for the works and all instruction issued on site could be directed to him. He has a good command of English. He is able to brief in detail on this method statement before the works commence.
1. Chainman 3
2. Surveyor 1
3. Chip Spreader Operator 1
4. Rubber Roller Operator 2
5. Mechanical Sweeper Operator 1
6. Dump Truck Driver 4
7. Bitumen Distributor Operator 1
8. Transport Light Truck Driver 1
9. Pick-up Driver 1
10. Flagman 2
11. Experienced Labor 8

B. Equipment
1. Chip Spreader 2
2. Mechanical Sweeper 1
3. Rubber Roller 2
4. Bitumen Distributor 1
5. Dump Truck 4
6. Transport Light Truck 1
7. Pick-up 1
Two thousand meters of half lane width are expected to be placed each day, that is to say, one thousand meters of full lane width per day.

C. Method Statement
Layer pavement method is adopted for double surface dressing. Usually by this method, a layer of bitumen shall be first spread followed by the spreading of a layer of aggregate. The construction procedure of double surface dressing is indicated below:
Preparation of surface
Initial rolling
1st Layer：
Aggregate
Rolling
1st Layer： 80/100 Bitumen
2nd Layer：
80/100 Bitumen

2nd Layer：
Aggregate

Broom drag
and final rolling

The details of procedure as following:
1. Preparation of surface
Ahead of double surface dressing construction, clean surface should be prepared so as to expose the majority of aggregate. Meanwhile, bumpy and rough road sections must be repaired and leveled. The weatherglass will be used to monitor the temperature of the road surface, whenever the temperature of the road surface falls below the temperature that be depicted in section 4304(a) of the Standard Specification for Road Works, no blinder shall be sprayed. No bituminous work shall be done during foggy or rainy weather.
Where newly constructed base or shoulder areas are to be sealed, the surfaces shall be checked for compliance with the surface tolerances and all other requirements specified. Any portions that do not meet these requirements shall first be either corrected or removed and reconstructed before they are sealed.
The road will be demarcated the area of the primed base to be sealed by means of setting out wire lines down each edge of the specified seal width.
2. Spreading of bitumen
After the full seepage of the prime coat bitumen, the first layer of bitumen will be spread following the requirement of specification. The bitumen should be spread homogenously without the phenomenon of blank space or accumulation. Spreading length of bitumen shall corporate with the capacity of aggregate spreader and the spreading of aggregates long time after spreading of bitumen must be avoided Concrete kerbing and channeling as well as any other structures adjacent to the road shall be protected against staining by bitumen being sprayed.
The test for spreading rate of the binder and aggregates shall be done before spreading works, the actual rates of application of binder and aggregate to be used in the construction will be determined by the engineer after finishing the test. The bitumen will be heated by bitumen heating plant in camp and be transported to site by the bitumen distributor, at the same time the bitumen can be heated whenever by bitumen distributor’s heating system on site.
In the joints between binder sprays, the armor plate (length: 1.5m) or building paper (length: 1.5m) will be used to cover the joints to prevent additional binder application onto the previously treated section.
3. Aggregate
Aggregates are to be spread once the bitumen spreading is completed. According to the specification, sufficient quantity shall be spread homogeneously. The superposition or blank space of aggregates should be prevented. In the occasion of aggregate gap in certain part, timely manual filling is to be conducted. The aggregate shall comply with the requirements given in Section 4502(b) in the Standard Specification for Road Works 2000 TANZANIA.
4. Rolling
① Initial rolling of aggregate
Immediately after the aggregate has been applied, rolling shall be commenced. A self-propelled 16 tons pneumatic-tyred roller shall be used to the case. Rollers shall operate parallel to the center line of the road, from the shoulders inwards the crown of the road, until the entire surface has been covered at least three times with the wheels of the roller.
② Broom drag and final rolling of aggregate
After the bituminous binder has set-up sufficient to prevent any aggregate from being dislodged, the surface shall be slowly dragged with a broom drag to ensure even distribution of the aggregate. After completing the spreading of the aggregate, the surface shall be rolled with the same procedure of initial rolling.
5. The joint between adjacent section
a) Longitudinal joint：Double surface dressing construction is half width construction. One edge of first half width is the edge of base. After the completion of first half width construction, it is required to treat the other edge:
l Align this edge to make it regular
l Utilize instruments to clear the parts beyond the alignment, inclusive of aggregate and excessive bitumen, so as to dress and tidy the edge.
b) Transverse joint: Prior to construction the following day, same treatment like method a) needs to be performed for ending part of double surface dressing which was done last day.
Construction of next half width and next day could be followed as items no.1- no.4 mentioned above. Provided that the third half width construction is required on site, previous working procedures can be repeated.

D. Measurement and Payment
The work shall be measured and paid for under section 4500: Double Surface Dressings.

E. Environmental protection
1. This work will be executed in accordance with Section 1700: Environmental Protection and Waste Disposal.
2. The construction will also be executed in accordance with the approved ESMP.
3.
F. Health & Safety
The construction will be executed in accordance with the approved HSMP.

G. Traffic Control
The traffic will be a single lane when double surface dressing, half width will be constructed and another half width will be as diversion, traffic will be transferred from one half to another half. Few occasions may occur that there will be a diversion outside of the road, in which situation traffic will be transferred from road to the diversion. The assigned persons will carry out the relevant traffic control work, the road signs will be installed in accordance with the sketch “Typical single lane traffic control details” Appendix C) in the latest version of the TMP.
H. Quality Control
The temperature of weather and bitumen will be recorded at intervals of every 20 minutes, to insure the temperature’s meeting the section 4304(a) of the Standard Specification for Road Works. The spreading rate of bitumen and aggregate shall be tested every 200m, and the density of aggregate shall be tested each 5000 m3. TFV, Grading and Flakiness tests shall be conducted in accordance with Table 7105/1 in Section 7109 (b) of the Standard Specification for Road Works.
Sinohydro Corporation Ltd. Page 5 of 5