碎石基层施工方案翻译-4月6日修改(共9页)

1、精选优质文档-倾情为你奉上Crushed Stone Base Construction Programme1. Purpose and Basis of the Programme1.1 Purpose: To guide the base construction in accordance with the Specification.1.2 Basis of the Programme1.2.1 Design DrawingsDWG. No.: TS-001/2 TS-002/2 CS-001/2CS-037/2 CRS-001/2CRS-070/21.2.2 Specificatio

2、nsWoreta-Woldiya Road Upgrading Project CONTRACT 2: Gob Gob - Gashena Bidding Documents Volume Ib Section Vi - Technical Specification：Part 1：General Specification 1205 Workmanship and Quality Control 1219 Remedial Work 3200 Placing and CompactionPart 2：Particular Specification 3407 Classification o

3、f Fill 3408 The Capping Layer 3700 Crushed Stone Base1.2.3 Other StandardsBS812: PART 1BS812: PART 3AASHTO T96AASHTO T104AASHTO T180 DAASHTO T1912. GeneralThe Woreta-Woldiya Road Upgrading Project Contract 2: Gob Gob Gashena with the initial station of 98+878.63 and terminal station of 184+800 has a

4、 total length of 85.92137Km. The base course will be crushed stone base with a quantity of m3.According to the general programme, the construction of base course will be divided into two sections to cover the part from Sta.134+300 to Sta.184+800 and Sta.134+300 to Sta.98+684 respectively. The road-m

5、ixing method and plant-mixing method will be adopted for the construction.3. MaterialsThe crushed aggregate will be employed as the material for base layer and the grading will conform to the grading given in Table 3702/1. The Aggregate Crushing Value will be no more than 25%, the Loss by abrasion w

6、ill not exceed 35%, the Loss of Sodium Sulphate Soundness will not exceed 12% and the Loss of Magnesium Sulphate Soundness will not exceed 15%.Flakiness Index: 35% Max.Liquid Limit: 20% Max.Plasticity Index: 6% Max.CBR: 80% Min.Sand equivalent: 25% Min.The material shall be plastic enough to be well

7、 compacted.Table-3702/1 Grading envelope crushed stoneSieve size (mm)Percentage Passing (by weight)Tolerance on target Grading (% passing by Mass)50.010037.595-100±2.019.060-80±6.09.540-60±8.04.7525-402.3615-300.68-22±6.00.0755-10±2.04. Workmanship4.1 Road-mixing methodThe p

8、rocess for road-mixing method will be as follows:Preparation of underlying layer Setting out Transportation and placing of aggregate Watering Mixing Shaping Rolling Maintenance.Prior to the commencement of any base course construction, a trial section of not less than 1000m2 in area will be laid to

9、demonstrate the suitable construction methodology including suitable equipment, mixing, paving method, rolling speed and passes and inspection etc., loose thickness and suitable length for execution. 4.1.1 Preparation of underlying layer and setting outThe underlying layer (subbase) will be checked

10、and approved complying with the quality requirement with an even and sound surface and specified crown before the commencement of base construction. Then the centreline will be reinstated over the underlying layer and one peg will be installed at an interval of every 15 to 20m for straight line and

11、every 10 to 20m for smooth curve to fix the contour line of the base course. And the indicating stake will be stand on the edge of both base sides, clearly marking the position of design level and loose thickness for the base.4.1.2 Transportation and placing of aggregateThe mixing ratio of crushed s

12、tone and chips will be calculated in accordance with Table-3702/1 Grading envelope crushed stone. The quantity of loose material will be calculated using the coefficient of loose laying (obtained from the test), compaction thickness, dry compacted density, width of base and intended placing length.

13、The paving area and stockpiling distance of the loading material will be calculated.The aggregate will be delivered before placing by dump truck with uniform loading capacity and the unloading distance will be strict controlled over the underlying layer.The underlying layer will be watered to suitab

14、le moisture content and where the area of which is too wet will be dried out to required moisture then spread by grader. Where oversize materials and layer exceeding the required thickness exist, it will be removed by hand and area without aggregate will be made good with qualified materials. The de

15、leterious material will be removed and the loose thickness will be checked to reach designed requirement. The traffic will be forbidden over loose crushed stone layer except the water truck.4.1.3 WateringThe water content will be tested on loose crushed stone layer and suitable content will be 1% mo

16、re than optimum water content. The water will be equally added into the material to avoid excess moisture if the water content is not satisfactory.4.1.4 MixingOn the completion of placing, the mixing frequency will be fixed by the test and the mixing will be carried out with grader. The aggregate wi

17、ll be mixed uniformly without segregation of coarse and fine materials and the water content will be 1% more than optimum water content. 4.1.5 ShapingThe shaping of the work will be initially carried out by grader after mixing the aggregate uniformly. It will be bladed more than one time, if necessa

18、ry, from both sides to the center of the road for straight line section and from inside to outside of the road for smooth curve. The surface after shaping will be rolled quickly by grader to expose the existing unflatness. The defects and discrepancies will be scarified, re-mixed and leveled. Then t

19、he materials exceeding the road level will be bladed out of the road by grader. The shaping work must have required slope and crown. The special care must be taken to make the joints clean and neat. In the process of shaping, the traffic and segregation of coarse and fine materials will be forbidden

20、. 4.1.6 RollingWhere the water content of mixture after Shaping arrives at the optimum water content or 1% more than optimum water content, the vibratory roller of 20T will be employed to roll full width of the surface. The rolling will be started from both shoulders to road center for straight line

21、 and smooth curve without superelevation and from inside shoulder to outside shoulder for curve with superelevation. The overlap width will be one half width of the wheel when rolling. The rear wheel of the roller must exceed the joint of two adjacent sections. The suitable rolling speed will be 1.5

22、 -1.7Km/h in the first two passes and then changed into 2.0 -2.5Km/h. The rolling passes will be as specified in the trial section. The stabilized crushed stone surface will be maintained moisture during rolling and watered to avoid rapid evaporation. The surface which appears as springing, loosenin

23、g or scaling will be scarified, re-mixed or replaced with suitable materials to required quality. Prior to the completion of rolling, the grader will be adopted in leveling work for the purpose of required crown and superelevation. Care must be taken to blade the material exceeding the surface level

24、 out of the road. The defects and discrepancies in local area will be left to remedy when placing the base layer. The turning or emergent braking of roller on the completed section or rolling section will be forbidden to ensure undamaged surface.4.1.7 Areas inaccessible to mechanical equipmentThe ma

25、terials on the area that cannot be reached by the equipment will be placed by hand with loose thickness of each layer not more than 100mm. The density will be tamped with the vibrating tamper to the required density.4.1.8 MaintenanceThe completed base will be watered, bladed or cleaned by water truc

26、k, broom drag and sweeper, keeping maintenance until such time as the prime coat is applied. The unprimed base course will not be open to traffic unless otherwise approved or designated by the Engineer.4.1.9 Joint treatment(a) Transverse joint treatmentThe overlapping of two sections will be mixed,

27、shaped and compacted together. A length of 5-8m in the first section left uncompacted after mixing will be mixed, shaped and rolled with the second section to design requirement.(b) Longitudinal joint treatmentThe base course will be divided into two parts from the centerline of the road for constru

28、ction when the temporary road cannot be got. Therefore, the longitudinal joint will be overlapped to mix. The side of first part with a width of 300mm will be overlapped with the second part for mixing, shaping and rolling to design requirement. 4.2 Plant-mixing methodThe process for plant-mixing me

29、thod will be as follows:Preparation of underlying layer Setting out Transportation and placing of aggregate Rolling Maintenance.Prior to the commencement of any base course construction, a trial section of not less than 1000m2 in area will be laid to demonstrate the suitable construction methodology

30、 including suitable equipment, mixing, paving method, rolling speed and passes and inspection etc., loose thickness and suitable length for execution. 4.2.1 Preparation of underlying layer and setting outThe underlying layer (subbase) will be checked and approved complying with the quality requireme

31、nt with an even and sound surface and specified crown before the commencement of base construction. Then the centreline will be reinstated over the underlying layer and one peg will be installed at an interval of every 15 to 20m for straight line and every 10 to 20m for smooth curve to fix the conto

32、ur line of the base course. And the indicating stake will be stand on the edge of both base sides, clearly marking the position of design level and loose thickness for the base.4.2.2 Transportation and placing of aggregateThe aggregate will be watered by sprinkling using water tank and mixed uniform

33、ly by loader in stock pile then delivered to construction site by dump truck. The spreader will be employed to carry out spreading work as per specified crown, width and thickness.The segregation of fine and coarse materials will be eliminated by appointed persons. The accumulation of coarse materia

34、l will be treated with fine material to mix uniformly and evenly. On the contrary, the fine material will be treated using coarse material.4.2.3 RollingWhere the water content of mixture after paving with spreader arrives at the optimum water content or more than optimum water content, the vibratory

35、 roller of 20T will be employed to roll full width of the surface. The rolling will be started from both shoulders to road center for straight line and smooth curve without superelevation and from inside shoulder to outside shoulder for curve with superelevation. The overlap width will be one half w

36、idth of the wheel when rolling. The rear wheel of the roller must exceed the joint of two adjacent sections. The suitable rolling speed will be 1.5 -1.7Km/h in the first two passes and then changed into 2.0 -2.5Km/h. The number of rolling passes will be as specified in the trial section. 4.2.4 Areas

37、 inaccessible to mechanical equipmentThe materials on the area that cannot be reached by the equipment will be placed by hand with loose thickness of each layer not more than 100mm. The density will be tamped with the vibrating tamper to 95% of required AASHTO T180 density.4.2.5 MaintenanceThe compl

38、eted base will be watered, bladed or cleaned, keeping maintenance until such time as the prime coat is applied. The damaged base part caused by the opening of the road to traffic will be scarified and restored. 4.2.6 Joint treatment4.2.6.1 Joint treatment in the same layer(a) Transverse joint treatm

39、entThe mixture near the spreader left uncompacted will be rolled and compacted with the mixture paved in the following day. Special attention will be paid to the water content of the mixture. The water if necessary will be added into the mixture to specified requirements.(b) Longitudinal joint treat

40、mentThe half width construction method will be employed in this Project when the detour road cannot be constructed. Therefore, the longitudinal joint will be joined vertically. When the construction of the first half width starts, the wooden form or steel form will be made as bracing for the side ne

41、ar the other half width. The height of the forms will be the same as the compacted thickness of the mixture. And the forms will be removed prior to the construction of second half width. Alternatively, a slope will be formed in the area of 30cm near the uncompacted boundary when the forms are not applied to the first half width construction. Therefore, prior to the construction of the other half width, the uncompacted area and the portion doesnt meet the crown requirements will be scarified and watered and then leveled and rolled with the placed mixture.4.2.6.2 Joint treatment in differe