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International Concrete Abstracts Portal

Showing 1-5 of 10 Abstracts search results

Document: 

SP83-08

Date: 

October 1, 1994

Author(s):

David W. Moller, Henry L. Minch, and Joseph P. Welsh

Publication:

Symposium Papers

Volume:

83

Abstract:

The Helms Pumped Storage Project is a new hydroelectric facility located in the Sierra Nevada mountains O f California. During excavation of the underground powerhouse complex, a previously unidentified shear zone was encountered in the granitic rock. The shear zone was a near vertical plane, up to 35 ft. in stratigraphic thickness, and was intersected by several tunnels near the powerhouse. During initial water filling of the power tunnel, the shear zone became a conduit for high pressure tunnel water (818 psi), allowing it to leave the power tunnel and seep into adjoining dry access tunnels. An innovative grouting program utilizing ultrafine cement (Blaine fineness of 8,880 cm /g) and pump pressures which were increased progressively with depth (up to 700 psi) was used to create a barrier between the pressure tunnel and the shear zone. The grouting program successfully reduced ground water pressures and seepage downstream of the barrier to acceptable levels. The program demonstrated the superior penetrating capability of grout made with ultrafine cement compared to type II and type III portland cement, and indicates that ultrafine cement grout can be an effective substitute for chemical grout when the properties of a cement grout are required.

DOI:

10.14359/6341


Document: 

SP83-02

Date: 

October 1, 1984

Author(s):

Luigi P. Gonano and John C. Sharp

Publication:

Symposium Papers

Volume:

83

Abstract:

Innovative aspects of the design and construction of the concrete-lined high pressure tunnels of the Drakensberg Pumped Storage Project are described. These tunnels located in weak argillaceous rocks are prestressed and designed to remain crack-free at internal pressures up to 6.2 MPa. The extension of an innovative grouting technique developed in Europe provided an economical and technically acceptable alternative to steel liners. Design criteria for structural deformability, prestressing and creep behavior were developed using a prototype-scale test chamber. The design models and practical technology developed for interface grouting will allow the use of concrete linings in pressure tunnels with greater internal pressures and with poorer rock conditions than previously considered feasible.

DOI:

10.14359/6335


Document: 

SP83-03

Date: 

October 1, 1984

Author(s):

Della M. Roy, M. Perez, B.E. Scheetz, and P.H. Licastro

Publication:

Symposium Papers

Volume:

83

Abstract:

Changes in length and volume of cementitious grouts for use in nuclear waste isolation have been investigated, and com-pared with the behavior of other mixtures, neat cement pastes, fly-ash containing mixtures, and mixtures with high-range water reducers (‘superplasticizers’). Expansive and non-expansive for-mulations are compared with respect to their changes in length and volume, both at atmospheric pressure and elevated curing condi-t ions, including those simulating placement under pressures of up to 1600 psi hydrostatic.

DOI:

10.14359/6336


Document: 

SP83

Date: 

October 1, 1984

Author(s):

Editor: Joseph P. Welsh / Sponsored by: ACI Committee 552

Publication:

Symposium Papers

Volume:

83

Abstract:

A study and report on the application and use of cement grouting techniques. Includes chapters on: the use of condensed silica fume in grouts; design and grouting of a concrete lined high pressure tunnel; changes in length and volume of cementitious grouts; drilled pier foundation rehabilitation; acoustic emissions as a nondestructive testing method; low slump compactive tail shield grouting in soft ground; bentonite effect on pumpability of compaction grouts; ultrafine cement pressure grouting; and cold weather cement grouting and post tensioning. Note: The individual papers are also available as .pdf downloads.. Please click on the following link to view the papers available, or call 248.848.3800 to order. SP83

DOI:

10.14359/14040


Document: 

SP83-07

Date: 

October 1, 1984

Author(s):

Roy Borden and Daniel M. Groome

Publication:

Symposium Papers

Volume:

83

Abstract:

Prediciting production pumping rates is an important part of estimating the required time and resultant cost of completing a particular grouting project. Due to the very stiff nature of low-slump grouts, pumping at economical flow rates can require the use of very high pressures. In practice, numerous admixtures are used to increase the "pumpability" of these stiff grouts, as definged by the lowering of the pressure required ot achieve a given flow rate. In this experimental study, the influence of the admixture bentonite, in amounts up to 15 percent of the pozzalan content, on the flow rate versus pumping pressure relationship, was investigated in field tests using production scale equipment. Constant diplascement piston pumps were used to achieve flow rates of up to 5cu. Ft./min. resulting in pumping pressures of up to 700psi. Over the range of flow rates and resultant pressures investigated an optimum bentonite content of 5 to 10 percent was achieve a given flow rate. The optimum bentonite content was observed ot increase from approximately 5 to 10 percent as the flow rate increased from slightly less than 1 cu. Ft./min. to about 4 cu. Ft./min.

DOI:

10.14359/6340


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