FLOOR SCREED WORKS

1.0 OBJECTIVE

1.1  To describe the procedure, for laying of floor screed for the contract no GTC.101/ED/01 Engineering, Procurement, Installation and Commissioning (EPIC) of Ras Laffan Utilization Project –Buildings and utilities and support service Phase 1-Utilities.

2.0 SCOPE

2.1 Applicable to all the buildings in at Service Base Area, Service Berth Area, FSO Marine and Telecom buildings.

3.0 REFERENCE

3.1  Project Approved Drawings

• Qatar Petroleum standard Spec. Vol. 1, section 9.39

4.0 PROCEDURE

4.1 MATERIALS APPROVAL:

4.1.1 Material approval shall be obtained from QP for the screed ingredients such as sand, cement, water, floor hardener, joint fillers etc before proceeding with actual work.

4.2 SURFACE PREPARATION:

4.2.1 The surface of the concrete base must be clean firm and rough to ensure a good bond. This shall be achieved by hacking thoroughly  to remove all laitance and to expose the aggregate over the whole area, followed by sweeping clean and hosing down to remove all dust.

4.2.2 The base shall be soaked with water for at least 12 hours and surplus water removed before laying commences.

4.3 LAYING OF SCREED:

4.3.1 Prior to laying the screed a thick brush coat of wet cement grout shall be applied to the damp surface of the base concrete and shall be well scrubbed in. The brush coat must not be applied more than 10 minutes before it is covered with screed cement and sand mortar shall be composed of one part of cement to three parts of sand by volume. Screeds shall be laid in one coat to the thickness shown on the drawings, laid level or finished to falls, cross falls and slopes as required. Screed boards shall be used at perimeters and at intervals not exceeding 2m to ensure even thickness or regular falls.

4.3.2 The mix shall only contain sufficient water to evenly spread to a thickness approximately 10 mm greater than the required thickness of screed. The screed shall be then thoroughly compacted by tampering and drawing off to the required level with a screed board.

4.3.3 The screed shall be laid in alternate length of the bays maximum 15m² with pain butt joints and the length of the bay shall not exceed 11/2 times the width. Movement and construction joints in the base shall be carried through the screed.

4.3.4 Final surfaces of the screeds shall be floated or trowel led as required by the finishing materials to be laid there on.

4.3.5 Tolerance for screeds including screeds laid to falls should be 63 mm in 3m in any position. There shall be no depression causing water to lie on surface. 

4.3.6 As soon as the bay is completed and has hardened sufficiently to prevent damage to its surface it shall be covered with polyethylene or similar sheets, which shall be adequately lapped and held down. The screed shall not be allowed to dry out for a minimum period of 7 days and no traffic shall be permitted on the surface during this time.

4.4 SITE CLEARANCE:

4.4.1 On completion of screeding work,  arrangements shall be made for curing of the screed and then the site shall be cleaned, clear off all the excess mortar/screed materials, rubbish etc. from the site to rubbish skip.

4.4.2 Request for Inspection shall be submitted to QP for final inspection and acceptance.

5.0 RECORDS :

• Material approval report.

• Inspection reports.

• Checklist.