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SECURITY AND SAFENESS GMS Ben Luc Long Thanh Expressway Project Package A5 Civil Works Km 32+450 to Km 35+900 CONSTRUCTION METHOD STATEMENT FOR AGGREGATE SUBBASE, BASE COURSES AND ASPHALT TREATED BASE[.]

CONSTRUCTION METHOD STATEMENT FOR AGGREGATE SUBBASE, BASE COURSES AND ASPHALT

TREATED BASE COURSE

TABLE OF CONTENTS

I AGGREGATE SUBBASE AND BASE

II ASPHALT TREATED BASE COURSE

I AGGREGATE SUBBASE AND BASE

1 Reference standards

All the material was tested and approved by Engineer before using The Contractor shall submit to the Engineer to know about the source

of material and the Engineer will approve these sources before the material is delivery to site Where the material does not meet the requirements of Technical Standards, the Contractor shall provide materials from other sources The transportation of materials from the processing stage will be accompanied by the manufacturer's certificate and report of testing to indicate that material in accordance with the requirements of the specification

The following Standards in their latest edition shall be particularly applied to the works covered by this Specification Section:

TCVN 8859:2011 Graded Aggregate Base and Subbade Pavement –Specification for Construction and Acceptance TCVN 8864:2011 Standard Test Method for Measuring Road PavementSurface Roughness Using a 3.0 m Straight Edge 22TCN 332-06 Testing procedures on definition of CBR value for soiland macadam in laboratory 22TCN 333-06 Procedures of soil and macadam compaction in laboratory 22TCN 346-06 Testing procedure on definition of compaction of roadfoundation and embankment by sand cone method AASHTO T104 Soundness of Aggregate by use of Sodium or MagnesiumSulphate. AASHTO T180

Standard Method of test for Moisture-Density Relations of Soils Using a 4.54-kg (10-Ib) Rmmer and a 457-mm (18-in) Drop

2 Material

Materials of construction must, before putting in the work, be tested to check the grain composition analysis, the best moisture if meet the technical standards and regulations approved by the Engineer will be allowed to spread

In addition, all construction materials of macadam aggregate foundation must meet the technical requirements specified in the Regulations and Specification

Table 1 : Grading Requirement for Aggregate

Standard (mm)

Mass Percent Passing

Dmax= 37.5mm Dmax= 25mm Dmax =19mm

19 58 - 78 67 - 83 90 - 100 9,5 39 - 59 49 - 64 58 - 73 4,75 24 - 39 34 - 54 39 - 59 2,36 15 - 30 25 - 40 30 - 45 0,425 7 - 19 12 - 24 13 - 27 0,075 2 - 12 2 - 12 2 – 12 Table 2 : Aggregate Subbase and Base Properties

No Properties Aggregate Test Method

Base Subbase

1 Los-Angeles wear of

aggregate (LA), %

≤ 35 ≤ 40 TCVN7572-12:2006

2 Soaked CBR at maximum drydensity ≥100 - 22TCN332-06

3 Liquid Limit (WL), % ≤ 25 ≤ 35 AASHTO T89-02 (*)

4 Plasticity Index (Ip), % ≤ 6 ≤ 6 AASHTO T90-02 (*) 5

PP Index = Plasticity Index Ip

x % material passing portion 0.075mm

≤ 45 ≤ 60

6 Percent by weight of

aggregate with diamond or flattened shape, %

≤ 18 ≤ 20 TCVN 7572-2006

(**)

7 Compacted Density (Kyc), % ≥ 98 ≥ 98 AASHTO T180

No Properties Aggregate Test Method

Base Subbase Note:

(*) Liquid Limit, Plasticity Index are specified by test with material passing sieve

0,425mm

(**) Aggregate with diamond or flattened shapes is sieve with thickness or width is

less than 1/3 length or equivalent;

- Test is conducted with various sieves of diameter of more than 4.75mm and account for more than 5% of sample quantity;

- Aggregate with diamond or flattened shapes content of taken sample is average results certified for each sieve

Aggregate with a Dmax = 37.5mm is appropriate for Sub-base

Aggregate with a Dmax = 25mm is appropriate Base course;

3 Equipment and checking

The Contractor shall arrange the construction equipment with good quality for the implementation of project

All kinds of construction equipment have been tested and registered for its activities And they are mobilized for the project was approved by the Engineer.Use of equipment with the best performance, ensure high productivity, good quality, low cost, and reducing of the hard work for employees

Technology chain must focus on synchronous and the balance between plant productivity and manual labor It must be based on characteristics of the Works and construction technology, Schedule, scope of work and other requirement in the Projects

Regular and timely improvement of construction equipment and manual labor in order

to ensure consistency, balance and facilitate the application of advanced construction technology

Constantly improve the management level, technical level and take the repair construction equipment, well observed periodic maintenance and repair for equipments

Equipping with proper facilities for the technical maintenance and repair of construction equipment, corresponding to equipped capacity

Construction equipment and material shall be managed and organized and stable in the construction group as well as highly specialized

The management and use of materials, equipment (including use, maintenance and moving) must comply with the specification of manufacture and competent authorities for the driver, operator …Assign the driver, driver and operator to match with trained professionals and workers of skills

The vehicles, construction machines were put into operation, ensuring the technical reliability and safeness For these vehicles, construction machines must be registered for safety, before being put into execution, must fulfill the registration test under the provisions of the competent authorities of the State of Vietnam

The technical maintenance must be done by the competent group To organize a team

of professional maintenance and repair techniques for each type of construction equipment and machines

Construction Equipment in the surface layers include as follows:

1 Bulldozer ≥110 HP each 03

2 Excavator 0,8-1,2m3 each 04

3 Asphalt concrete mixing plant 100 ton/h 02

4 Aggregate Spreader 110 HP each 02

5 Asphalt concrete machine with automatic tenso≥ 6m each 02

6 Roller 16 - 25ton each 04

7 Steel roller 10 – 12 ton each 04

8 Rubber-tired roller ≥20T each 04

9 Dump trucks ≥8m3 each 12

Equipment for surveying work

- Waterlevel : 02 each

- Ruler, mirror, rod : 04 each

- Meter for accuracy 0,1 mm : 02 each

Equipment at site:

- Equipment for checking of the moisture : 01 set.

- Equipment for checking the flexibility of soil : 01 set

- Equipment for checking the soil liquid : 01 set

- Standard sieve : 01 set

- Circle knife for taking sample of soil : 01 set

- Taking the soil sample by pouring of sand : 01 set

4 Construction of aggregate Base and Subbase layers

4.1 Preparation of road form.

After the completion of road base, the preparation the road mold in according to the specification, including repair of defects on the top of road base K98, in the detail as follows:

- Repair the all defects on the road, to clean the surface, to wet the surface

- Setting up the road mold before commencement of work The contractor will carry out the repair the road mold to ensure its accuracy, sufficient dimension in shape To construct the fish bone ditch both sides of road with distance of 10 -15m, to set up 01 water drainage trench

4.2 Equipment and Manpower

The Contractor spread the macadam aggregate by the sprayer, in combine with the grader (approved by Engineer and Employer)

Spread layer thickness is allowed a maximum of 18cm (after compacting), spreader has the vibration bar to ensure the density  90% immediately after spreading

The test equipment in the construction process:

- Dice control the thickness and ruler for slope

- The standard sieve and balance for analysis of grain

- The sand equivalent weight measure test (to check for dirt)

- Equipment determine the moisture content of base and subbase

- Fully equipped the devices for testing of macadam aggregate in lab and site of Contractor

- Testing set for the sand pouring to check the density

Other construction equipment beside of the spreader:

Dump truck

Water spray equipment in all phases of construction: tank truck, water pump with tap, water sprayer with portable showers watering by hand

The compaction equipment:

- Static steel roller 10 - 12T

- Vibration roller 16-25 T

- Static steel roller 10 – 12T

5 Execution of base and aggregate subbase foundation

5.1 Construction of aggregate Subbase

The thickness of the macadam aggregate layer type 2 is 40cm, so it is divided into 3 layer for the construction, the below layer of 18cm thickness, and the upper layer of 14cm thickness to facilitate the construction as well as the moving

5.2 Testing spreading

Equipment for the work must be mobilized to site and setting up the construction site before commencement of work The construction equipment includes of transportation truck, water spraying equipment including tank truck, pump with hose, hand watering sprayer, spread machine, the compaction means including steel rollers 10-12 T, Bomag vibrator, SAKAI vibrator 16 - 25T

Determining the spreading coefficient

The spreading coefficient K is determined by formula:

Cmax K

Ksp =

Ctn

In which :

- Cmax: The maximum dry density of macadam aggregate according to standard result of testing density

- K: is defined density equal to or greater than 0.98

- Ctn: dry density of macadam aggregate has not been compacted (according to my experience can get Ksp = 1.28  1.38)

5.3 Construction technology of macadam aggregate includes of the following steps:

Material preparation: Subbasebe watered at the stocking yards for ensuring that the humidity is greater than the optimum moisture content from -2% ÷ 2%

Transportation of subbase

Grading and spreading of subbase

Rolling and compacting to specified density

Maintenance of subbase and spraying of the asphalt to the upper layer.

5.4 The sequence of construction as follows:

Piling of the piles, stretching wire to the level so that the macadam after spreading and compacting san will achieve the designed thickness of 12cm of layer 3 and to 14cm of layer 1,2

Macadam aggregate after exploiting in the quarries, gathered at the dump are (to check the character of macadam aggregate at the dumping area and approved by Engineer in writing) Using the excavators to load to the dump truck then transported to the site (macadam aggregate must be met the needed moisture to prevent the segregation in the transportation The loading is done by reverse bucket excavator, tires pouring into the hopper of the spreader (the height of the bottom dump truck just high the spreading layer maximum 0.50 m to avoid segregation), adjust the spreader to ensure spreader material thickness properly designed

Spreading width is calculated wider than the requires 20 cm to roll the outer edge also achieving the specified density and pressure When construction of the behind trail adjacent to in font trai is cut vertically to ensure the quality of compacting space between two adjacent trails spreading

The moisture of material is always best If it is not met the requirement, taking the adjustment by drying If the material is too dry, spray with water by shower trunk to avoid the drifting of the small particles The Contractor shall adjust moisture in yards for materials to ensure uniformity

In the construction process to regularly monitor surface elevation of macadam aggregate, the compensation or removing to the uneven areas shall be taken by worker, to ensure the macadam aggregate surface is always been flat, creating a compacting homogeneous mass, creating horizontal slope as designed

In case occurrence of segregation, ripples or improper during the spreading it must be taken the repair of it

There is a compensation after compacting, then the subgrade surface must be plough with depth of 5cm before spraying compensation

The compacting is done immediately after spraying with the sequence: preliminary rolling, tire rolling, vibration rolling and completion This process is done when the material approaches the density requirements Density of material is certified by the methods of pouring sand in the presence of the Engineer

5.5 Rolling sequence:

Rolling by Preliminary rollers 10-12T with 3-4 times / points with V = 1.5 -: - 2km / h

Use vibration roller when reaches 16-25T rolling 12 -18 times / points with V = 2.5 -:

- 3 km /h

Rolling for completion by steel roller 10-12T, with 3-4 times / points with V = 3 km / h

Number of times be determined be needed rolling through the test results to achieve density requirements

It must be wet with water during the process to compensate for evaporation of water during construction and keep the surface moisture during compacting

5.6 Density requirements:

K  98% of the entire thickness level sprayed, in the process, it is regularly checked density by the means of pouring sand

The contractor sprays test with a section of 500m2

The purpose of the tested spraying for the determination of pressure coefficient and number of rollers on a point, then giving the proposal from the construction requirements in accordance with the process and technological lines in fact in all the stages: prepare spread, compaction, quality control materials after shipment, check the availability of vehicle quality, motorcycles, to assign the proper manpower to each working assembly

After determining the coefficient of compacting pressure, compacting on a number of points and approved by the Employer and Engineer, will conduct spraying on a large scale

5.7 Spreading on a large scale

Setting up a working group for execution of foundation to undertake the work

The construction on a large scale is done as above tested section

Spreading of materials:

- Subbase is carried out by Contractor into 3 layers with calculated thickness (before rolling), so as to achieve the designed thickness

- The material is sprayed with a width greater than design 20 cm - 40cm each side

of sprayed line to ensure no streaks spreading out when rolling and necessary pressure

- Compensation and rolling, retain the moisture

Setting up the rolling line after testing rolling Use a light roller (10-12T) to do preliminary compacting subbase, then use steel rollers and vibrating rollers to achieve density requirements

Number of rolling is based the actual results of after spraying try to achieve the necessary density and optimal rolling

It must be taken the remedy immediately or compensate material to the uneven points

or ripples during the spraying if there is any segregation or has not yet reached a density requirements, material of entire such place must be replaced on new macadam aggregate, no mixing or compensation in place Check regularly to monitor the sprayed materials so that the most appropriate, avoid the disproportion or putting the material Compacting right along the edges and gradually goes to the center vertically

At the location that the roller is able to access, the worker shall use the roller by hand

to compact to the required density

On the sections with horizontal slope, compacting gradually from the low edge to higher edge higher Compacting shall be continued until no wheel rolling tracks on the surface layer, material meet the density and stability

Process rolling is conducted as follows:

- Preliminary rolling : Stability rolling the aggregate by roller 1012T

- Compacting rolling : Vibration roller 16-25T

- Completion rolling : Steel roller 1012T

Checking the density by method of sand pouring

The macadam aggregate after being completed must be met the requirement of shape, level, density, flat and approved by Engineer and Employer

6 Construction of Base

Due to base layer with thickness of 35 cm so we shall divide into 3 layers, each layer has a thickness of 12cm To facilitate the construction as well as the movement for the construction equipment, to setting up the construction execution on ½ width of road.Base is sprayed by spreader

6.1 Testing spraying

The preparation of construction machinery: already available after completion of the subbase layer

Technology for execution of base layer also includes four steps as execution of the subbase layer

6.2 Spraying on a large scale:

Being carried out the same as the execution of macadam aggregate type 2

6.3 Curing of the macadam aggregate layer

No transportation vehicles are allowed moving on the surface of the base layer before spraying of the bitumen and kept regularly to water on its surface to ensure the