路拌法天然砾石水稳基层的英文施工方案.doc

Works Programme for Gravel Cement Stabilization Base ProgrammeI. Main construction methodThe base for the section of OGINGA ODINGA Road (KURA Project) shall be 150mm cement treated natural gravel material layer with cement content 2.5%. The natural gravel material shall be hauled to the field with 15T tippers, spread by the graders, blended by the pulmixer and compacted by the rollers. II. Construction of trial sectionThe 100m full-width trial section is scheduled to construct between km0+800 - km0+900 in advance before the overall commencement of base layer.1. The purpose of construction for trial section The purpose of trial section is to verify the following aspects:a) the proposed construction program and method are feasible or not;b) the deployment and matching of construction equipment and personnel are reasonable or not;c) the relationship between the rolling passes of roller, rolling methods and compaction density;d) to confirm the loose coefficient and loose depth of material spreading;e) to verify the range of tolerance between construction mix proportion and designed mix proportionThe trial section shall provide construction guidance and data for the overall construction.2. The data required to be collected during construction of trial sectionThe trial section must be undertaken under the direction of Engineer. The following details should be recorded: l the types of equipment and equipment quantity;l mixing time for stabilization layer; l rolling passes and method for rollerl loose paving thickness, level and moisture content of mixture before compacted;l actual thickness, level, moisture content and density of mixture after compacted;3. Testing items for the trial roadThe natural gravel material and cement shall be tested as per the Technical Specification before the commencement of trial road. The mixture and structural layer shall be carried out tests in laboratory as per the requirements of Technical Specification during the construction process and after construction finished. Only if the above tests data reach the requirements, the trial road can be approved. After getting the approval from the Engineer, the testing data will be the basis for our overall construction, and the trial section can be one part of the road, otherwise the Contractor shall find out the reasons and undertake the construction again.III. Preparation Works before Construction1. Construction setting-outa) Centrelines, the edge of shoulder and the edge of carriageway (total 5 points) of top level of base layer shall be calculated as per the interval of 20m, and then submitting the information to Engineer for approval.b) The centre and side lines shall be set out on site as per the interval of 20m, and the permanent wood controlling pegs (55cm) shall also be erected 50cm outside of the side pegs. The levels for the stabilization layer shall be controlled with string method.2. TestingThe gravel material and cement shall be tested completely before the commencement of trial road. The mix proportion (natural gravel material with cement) shall also be approved by the Engineer. The testing data, such as optimum moisture content, the maximum dry density and cement mixing proportion etc. shall be confirmed.IV. Construction methoda) The natural gravel material shall be hauled to the field with 15T tippers, and the required quantity for every chainage shall be dumped by the levelers calculation strictly. b) The dumped gravel material shall be spread and dry-mixed once by the grader to enable the labors to select and throw the big coarse size rocks (size over 5cm) out. After leveling, the material shall be slightly compacted by the roller and checked by the leveler to calculate if the gravel material satisfies the quantity for the stabilization layer.c) After confirmation for the gravel material, the lime shall be used to mark every one square meter to guide the site personnel to spread the cement uniformly on the surface of the natural gravel material.d) Pulmixer shall be used to dry-mix the gravel material and cement initially to ensure the two kinds of material are uniformly blended.e) The water tankers shall be used to spray enough water to the surface of the mixed material, following, the pulmixer shall be used to blend the mixture.f) After properly mixing, the roller shall be used to undertake the initial compaction, and the levels shall be cut with the string method.g) After finishing cutting levels, the mixture shall be compacted two passes with roller. Levels shall also be confirmed by the leveler as soon as possible, if any chainages levels need to be corrected slightly, the grader shall be mobilized to shape the surface to the design levels. On the completion of the levels, the steel roller plus tyred-roller shall be used to finish the compaction for the stabilization layer.IV. Curing1) Within 4 hours after compaction, the water shall be slightly sprinkled to keep the base surface damp, and then the minimum thickness of 0.1 mm polythene film shall be used for covering. Such films shall overlapped 50cm at the joints. The clean gravel material shall be piled on the joints and the edge of polythene film to keep the covering in place.2) Minimum curing period is 7 days. During the curing period, the workers shall be sent to patrol and prevent children or livestocks damaging the base layer. If any damage happens, repairing activities shall be undertaken