7+ Important points regarding Grouting System of a Dam Structure

Saad Iqbal | 🗓️Modified: June 16, 2015 | ⏳Read Time: 4 min | 👁Post Views: 149
The joints between waterstop are to be formed by heat fusing as per recommendations of the supplier. 
The contraction joints shall be pressure grouted with cement grout no sooner than 3 months after placement of the last lift of concrete at the joint to be grouted and when approved. 
V notch grout groves shall be formed in the contraction joints as indicated on the drawings. 
All pipe and fittings to be embedded in concrete shall be thoroughly cleaned of all dirt, grease, grout and mortar immediately. Before being embedded in the concrete. The pipe and fittings shall be firmly held in position during the placing of concrete. All parts of the grouting system shall be maintained free from water, dirt and other foreign substances. 
The edges of the cover plates adjacent to the concrete face shall be plastered with a stiff cement mortar or other approved material as shown on the drawings. This material shall insure closing of all openings between the plates and the face of the concrete to exclude cement, water and fresh mortar but shall permit opening between plate and concrete under pressure during grouting operations. Any indication of restrictions shall be corrected immediately before continuing the placement of the advancement placement.  
At such times as the engineer may direct, the grout system shall be tested to his satisfaction by forcing a current of air under pressure through it. Any pipe or grout groove that becomes clogged before the grouting of the joint is complete, for any cause, shall be opened or the contractor shall drill such holes, cut the concrete, and install such other pipes and fitting that in the opinion of the engineer will satisfactorily substitute for the blocked portion of the system. 
All grout and vent system headers should be checked and cleared of any obstructions. The compartment to be grouted shall first be checked for water tightness at half the maximum allowable pressure well in advance of start of grouting to avoid delays. Necessary repairs shall be made if leaks are found.
The pipes for grouting shall be color coated to allow easy identification in the field. 
Extra grout pipes shall be installed in order to have redundancy in the system in case one set of pipes get choked. 
All grout for pressure grouting contraction joints shall consist of Portland cement mixed with water in approved proportions. To prevent the grout from setting too quickly, the temperature of water used shall not be above 21 0C. 
The contraction joint shall be flushed with water and water left in the joint prior to grouting. A lean grout starter mix of water cement ratio of 3:1 by volume shall be forced in through the groove at the bottom of the grout lift while the value in the return header at the top of the lift. Pumping will continue until undiluted grout appears at the outlets of the top groove. Both outlet valves will then be closed and the pressure built up slowly until the prescribed maximum is reached. The pressure applied to the bottom of the lift shall be such that the resulting pressure at the top will be approximately but no in excess of 200 KPA. The grout will then be given time to spread out in the joints, during which time the pressure may drop, in the top as directed. This will be repeated until the joints hold the prescribed pressure for 30 minutes and until the grout has set at which time the grouting will be completed. 

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