水工隧洞混凝土缺陷处理施工措施

REV. NO.0REVISION DESCRIPTION REPUBLIC OF UGANDAMINISTRY OF ENERGY AND MINERAL DEVELOPMENTPROJECTPROCUREMENT OF EPC CONTRACT FOR600MW KARUMA HYDRO POWER PLANTEPC CONTRACTORDESIGNERHYDROCHINA HUADONG ENGINEERING CORPORATIONDOCUMENT TITLEEDITVERIFIEDAPPROVEDOWNERS ENGINEERLiu Zhi huiCHECKEDREFERENCEDATEZhang Jian pengliu YuM-GE-GE-005October,2016 ENERGY INFRATECH PRIVATE LTD.NEW DELHI , INDIAThis document is the sole property of MEMD and may not be published or made available to third porties without prior written consent.

Karuma Hydropower Plant and Associated Transmission Line Works

Manual For Concrete Defects Repairing Of TRT Lining

Ref: M-GE-GE-005

(Revision 0)

THE EMPLOYER: THE EPC CONTRACTOR:

THE GOVERNMENT OF REPUBLIC OF UGANDA, SINOHYDRO CORPORATION LIMITED REPRESENTED BY THE MINISTRY OF ENERGY AND MINERAL DEVELOPEMENT

October, 2016

CONTENT

1. Purpose ............................................................................ 错误！未定义书签。 2. Main Defects of Concrete Works..................................................................... 1 3. Major Techinical Measures For Repairing ....................................................... 1

3.1 Dislocation .............................................................................................. 1 3.2 Grout Leakage ........................................................................................ 2 3.3 Honey Comb ........................................................................................... 2 3.4 Pitted Surface ......................................................................................... 2 3.5 Cavity ...................................................................................................... 2 3.6 Local Depression and Groove ................................................................ 3 3.7 Reinforcement Exposure ........................................................................ 3 3.8 Crack and Cold joint................................................................................ 4 3.9 Protruded Reinforcement End ................................................................ 5 4. Quality Control ................................................................................................ 5

1. Purpose

To insure concrete quality shall meet standard and contract requirements after concrete repairing procedures.

2. Main Defects of Concrete Works

Common defects maybe occur in concrete works mainly include dislocation, grout leakage, honey comb, pitted surface, cavity, local depression and groove, reinforcement exposure, cold joint, cracks, protruded reinforcement end and so on.

3. Major Techinical Measures For Repairing

Once the type of the defect is identified, relative special-assigned personnel will be arranged to treat the various defects occur in different construction positions.

3.1 Dislocation

Repair methods for dislocation mainly include chiseling and polishing, then backfilled with equivelent strenth as the concrete. Different methods will be adopted according to different situation.

1) If the dislocation is not more than 20mm, grinding machine shall be used for polishing the surface to form a slope of 1:10.

2) If the dislocation is more than 20mm, pneumatic pick shall be used to trim the surface to form a slope of 1:10.

3) If only appearance requirement, fine aggregate concrete or mortar which is one grade higher than the original concrete shall be used for compacting and leveling the surface.

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3.2 Grout Leakage

The leaked grout shall be cleaned away. If in some positions, it’s hard to remove the grouting artificially. In such portions, grinding machine will be used for polishing and triming the surface and then use high pressure water to flush the surface.

3.3 Honey Comb

To chip away the loose material in the honey comb artificially or by pneumatic pick, and then use high pressure water flush the surface. Fine concrete or mortar, one grade higher than original concrete, shall be used for repairing the defect in the sequence of leveling, compaction and troweling. If honey comb occurres on overflow surface, intake, water channel or other water passage surfaces, firstly chip away the loose material in honey comb artificially or by pneumatic pick, wash the surface by high pressure water, dry the surface, and then use epoxy mortar which is one grade higher than original concrete to repair the defect in the sequence of leveling , compaction and troweling.

3.4 Pitted Surface

If pitted surface occurres on the surface with structure requirement or water passage surface, grinding machine shall be used for polishing and leveling the pitted surface. The surface shall be washed by high pressure water. If only requirement, mortar which is one grade higher than original concrete shall be used for repairing the defect in the sequence of leveling, compaction and troweling.

3.5 Cavity

To chip away the loose aggregate in the cavity until the completed and compacted concrete surface be exposed. Inverted trapezoidal shape is most proper for chipping shape (The chipping line is better perpendicular to facade of

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the surface or counter-slope with the included angle in the range of 45°~90° is most proper. Circular arc-shape chipping shall be avoided. Consequent-slope with an included angle between chipping line and surface more than 90° shall be avoided, because the filling material is hard to sticking under such condition). Then, wash the regular chipping surface by high-pressure water. Fine aggregate concrete one grade higher than original concrete shall be filled into the chipping area followed by compaction, leveling.

3.6 Local Depression and Groove

First of all, remove loose materials within the groove and the depth of chipping shall be according with the thickness of steel bar cover (mostly 3-5cm). The shape of chipping is preferred to be inverted trapezoidal (The chipping line is better perpendicular to facade of the surface or counter-slope with the included angle in the range of 45°~90° is most proper. Circular arc-shape chipping shall be avoided. Consequent-slope with an included angle between chipping line and surface more than 90° shall be avoided, because the filling material is hard to sticking under such condition).Then wash the regular groove with high pressure water and backfill the groove with mortar that is one grade higher than original concrete followed by compaction, leveling and troweling.

3.7 Reinforcement Exposure

Remove the concrete around exposed steel bar within 3-5cm (including the surface of steel) and the depth of chipping shall be according with the thickness of steel bar cover (mostly 3-5cm). The shape of chipping is preferred to be inverted trapezoidal (The chipping line is better perpendicular to facade of the surface or counter-slope with the included angle in the range of 45°~90° is most proper. Circular arc-shape chipping shall be avoided. Consequent-slope with an included angle between chipping line and surface more than 90° shall be avoided to make sure the filling material is easy to sticking, shaping regular groove and the steel

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fully exposed). Then wash the groove and steel with high pressure water and backfill the fine concrete or mortar that is one grader higher than original concrete in the sequence of compaction, leveling and troweling.

3.8 Crack and Cold joint

Concrete crack, according to their occurrence, is divided into surface crack、deep crack、penetrating crack. As to the surface crack, mostly there is no need to repair. Only when it occurs in the position which is required for the structure、overflowing and anti-seepage, the surface crack shall be sealed with cement mortar or epoxy mortar. The other cracks shall be dealt with through different methods on the basis of their location and width.

1) As to the crack and cold joint, if there is no requirement for the structure, overflowing and anti-seepage and the width of crack is not more than 1mm, it will not be repaired. And if the width of crack is more than 1mm, it shall be repaired through chipping the crack to become a trapezoidal trench (width 50mm and depth 30-40mm). Then wash the surface by high pressure water and backfill the trapezoidal trench with micro-expanding mortar in the sequence of compaction, leveling and troweling.

2) Upstream Split Crack: As for the upstream split crack, it shall be disposed by chipping the crack to be a trapezoidal trench (width 100mm and depth 50-70mm), and wash the surface with high pressure water, dry the surface with fire, then paint epoxy resin and backfill the trapezoidal trench with epoxy mortar in time followed by compaction, leveling and troweling.

3) Surface crack of concrete：Steel rebar spanning the crack will be used to prevent development of the cracks, and the distribution of the steel bars will be decided by the employer’s and contractor’s engineers jointly.

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4) As for the concrete crack of the construction work position which have structured and water scouring resistance requirements, send the surface, drill holes along the crack, and then grout.

3.9 Protruded Reinforcement End

As for the end in non-overflow surfaces, cut the end, and make it 1cm deeper than the surface ,then fill with grade of M20 motar. As for the end in overflow surfaces, cut the end, then remove the concrete around the center of the end within 50 mm and30 mm deep. Then wash it by high pressure water and backfill the hole with epoxy mortar in the sequence of compaction, leveling and troweling.

4. Quality Control

According to the standard and construction measure, construction quality shall be controlled strictly in order to make sure construction quality shall meet contract requirements concrete repair procedures.

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