1.     OBJECTIVE

The purpose of this method statement is to describe the activities and methods for the construction of plastering work.

 

2.     PLANT AND EQUIPMENT

2.1.  Portable Concrete Mixer

2.2.  Bar Benders

2.3.  Bar Cutters

2.4.  Circular Saw (Table Type)

2.5.  Portable Electric Grinders

2.6.  Portable Electric Jigsaws

2.7.  Mobile Crane

2.8.  Mixer Truck

 

3.     CONSTRUCTION METHOD

3.1.  Mix Design

3.1.1.     Request for design mix based on the concrete grades specified on structural drawings from the Ready Mixed Concrete Supplier.

3.1.2.     Submit the proposed design mix to client / client’s representative for approval.

3.1.3.     Strength test shall be carried out during the progress of work.

 

3.2.  Trial Mixes

3.2.1.     The trial mixes of each mix designs shall be carried out at Site in presence of the engineer using proposed plants and equipment and mixing methods.

3.2.2.     Fresh concrete test shall be carried out in accordance with EN 12350-2:2009.

3.2.3.     Six concrete cubes shall be taken from each trial mix, 3 tested at the age of 7 days and other 3 at 28 days. And also shall be cured in accordance with En 12390.

3.2.4.     Correlations between 7 and 28 days result shall be ascertained from trial mixing and testing.

 

3.3.  Material

3.3.1.     Cement

3.3.1.1.    Cement will delivered on site from supplier packed in cement bags of 50kg per each bags. With each shipment of cement, the supplier shall provide manufacturer certificate that shows the cement has been tested.

3.3.1.2.    Cement stored outside shall be covered with tarpaulin or canvas.

 

3.3.2.     Aggregates

3.3.2.1.    Aggregates shall be naturally occurring sand, gravel or stone, crushed or uncrushed except otherwise specified and shall comply with M.S.29.they shall be free from adhering coatings and shall not contain any harmful material, insufficient quantity so as not to affect adversely the strength, durability and permeability of the concrete.

3.3.2.2.    Test shall be carried out an samples of the supply at intervals as directed by the client representative or whenever there is a change of source. Any batch of aggregate found non-compliance with requirement shall be withheld from batching.

3.3.2.3.    Aggregate shall be handled and stored to minimise segregation and contamination and store in open stockpile on stabilized ground.

 

3.3.3.      Water

3.3.3.1.    Water will be supplied from local water supply authority and shall comply with requirement of MS 28. It shall be clean.

 

3.3.4.     Admixtures

3.3.4.1.    Suitable admixtures may be used in the concrete mixes with the prior approval of or as directed by the client representative.

3.3.4.2.    All requirement and sampling, acceptance test, uniformity test, independent test, chloride content, information to be provided by the manufacturer including compliance certificates and markings shall be in accordance with specification.

3.3.4.3.    Additional test shall be carried out at the request of client representative.

 

3.3.5.     Steel Reinforcement

3.3.5.1.    Steel reinforcement comprises hot rolled mid steel, high yield steel, steel fabric reinforcement, etc.

3.3.5.2.    Manufacturer’s test certificate shall be generally accepted as proof of soundness. Additional test shall be carried out at the request of client representative to confirm the characteristics strength of steel reinforcement.

3.3.5.3.    Steel Reinforcement shall be in clean and free from loose rust, mill scale, oil, grease, paint, dirt or anything which may reduce its bond with concrete.

3.3.5.4.    Bars shall be of their correct lengths and bent to the exact shapes required before being fixed in the work. Bar shall be cut and bent cold by the application of slow steady pressure or in a bar bending machine.

3.3.5.5.    Reinforcing steel shall not be welded without the prior approval from the Engineer.

 

3.4.  Work Methodology

3.4.1.     Formworks

3.4.1.1.    General

3.4.1.1.1.   Formworks shall include all temporary or permanent forms required for forming the concrete together with all temporary construction required for their support.

3.4.1.1.2. When the use of proprietary type (system) of formwork are proposed by the Main Contractor, the supplier or manufacturer shall submit the relevant design endorsed by a Professional Engineer, together with the warranty of their products to the Main Contractor.

3.4.1.2.    Fabrication

3.4.1.2.1. The type and treatment of any lining (plywood, metal, plastic, timber, etc.) of the forms shall be selected correctly in accordance to the concrete finish required.

3.4.1.2.2. The carpentry working area shall be located in the designated fabrication yard at site.

3.4.1.2.3. The subcontractor‘s supervisors shall check and select the right type of formwork for the works. The formworks shall be checked for twist, bowness, squareness, length, size, pinholes, stain and etc.

3.4.1.2.4. The Foremen of each carpentry gang shall be responsible for marking out the dimension and size for fabrication.

3.4.1.2.5. The Supervisor will check the fabricated components such as base panel, side panel, and boxed form and curved form for straightness squareness and security of nails etc.

3.4.1.2.6. Every fabricated components shall be properly stacked bundled and tied together for easy handling. Each bundle shall be marked using tag or by inscribing with waterproof marker pen indicating the designated area to used.

 

3.4.1.3.    Storage Handling and Transportation

3.4.1.3.1. When the component is scheduled to be used as per Work Programme, Site Agent shall make arrangement for delivery to the designated locations.

3.4.1.3.2. Truck will be used for the transportation of fabricated component to the designated area. Mobile crane will be used to lift the materials to the truck. Unloading at designated area can be executed either by a mobile crane or tower crane depending on the location.

 

3.4.1.4.    Placement of Lean Concrete

3.4.1.4.1. Lean concrete shall be placed on a well formed, dry sub-base for the purpose of separating the structural concrete with sub-base material during the placement of structure concrete. Formwork installation shall be done on the lean concrete.

 

3.4.1.5.    Installation

3.4.1.5.1. The surveyor will first step up a reference line offset from the nearest TBM or from a previously constructed structure with established survey data.

3.4.1.5.2. The subcontractor’s Supervisor shall determine the side line of the structure by offsetting from the given reference line using string and measuring tape.

3.4.1.5.3. For structure above ground level, the use of theodolite and plumb bob will be required to assist the supervisor in determining the side line and also to check the verticality of the form.

3.4.1.5.4. Before installation of formwork, the supervisor shall survey the level of the lean concrete and ensure that the base is clean.

3.4.1.5.5. or horizontal structures above ground level, base formwork shall be first placed and adjusted to the required level through height controlling jacks incorporated in the metal props and scaffolds  frames.

3.4.1.5.6. For columns, formworks are put into position after placement of reinforcement steel bars.

3.4.1.5.7. In the case of horizontal structures, one side of the form shall be erected initially along the stringed side line. Temporary struts and shores are placed to hold the form in position.

3.4.1.5.8. After the placement of steel bars the other side of the formworks shall be erected. Straightness and verticality check executed and struts secured in place together with horizontal braces to maintain the required width throughout.

3.4.1.5.9. Where holes are needed in formwork to accommodate projecting reinforcement, services or fixing devices, care shall be taken to prevent loss of grout when removing formworks.

 

3.4.1.6.    Preparation before Concreting

3.4.1.6.1. Before concreting the subcontractors’ Supervisor shall ensure that all forms are thoroughly cleaned out and free from sawdust, shaving dust, mud or other debris by using air compressor.

3.4.1.6.2. The inner surfaces of formworks except for permanent formwork or unless otherwise approved by the Supervising Engineer, shall be coated with mould oil diesel or other approved material to prevent adhesion of the concrete. Such release agents shall not come into contact with the reinforcement. For any exposed surface only one release agent shall be used throughout the entire area.

3.4.1.6.3. All formworks after preparation shall be inspected by the Supervising Engineer immediately prior to concrete.

 

3.4.1.7.    Striking of Forms

3.4.1.7.1. The Subcontractor shall inform the Supervising Engineer and obtain his approval before striking any formwork.

3.4.1.7.2. The removal shall be done in such a manner as not to damage the concrete and shall take place at times to suit the requirement for its curing.

3.4.1.7.3. The minimum periods between concreting and the removal of form are given in Table 2 Appendix A.

3.4.1.7.4. Where it is intended that forms are to be reused, it shall be cleaned and made good by the subcontractor to approval of the Supervising Engineer.

 

 

3.4.2.     Steel Reinforcement

3.4.2.1.    Material delivery storage and handling

3.4.2.1.1. Reinforcement steel bars shall be delivered to site progressively and in accordance to the delivery schedule.

3.4.2.1.2. Reinforcement shall be secured against displacement. Unless specified otherwise, the actual concrete cover shall be taken as the distance between face of concrete to the nearest steel surface.

3.4.2.1.3. Reinforcement temporarily left projecting from the concrete or other joints shall not bent out of position during the periods in which concreting is suspended except with the approval of Supervising Engineer.

3.4.2.1.4.