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Home > Publications > 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
SP83
October 1, 1984
Editor: Joseph P. Welsh / Sponsored by: ACI Committee 552
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
10.14359/14040
SP83-01
Pierre-Claude Aitcin, G. Ballivy, and R. Parizeau
Condensed silica fume is a by-product of the fabrication of silicon or ferrosilicon alloys. It is composed of very fine glassy spheres of quite pure silica having an average diameter of 0.1 pm. It is a very reactive pozzolan that has been found to increase drastically the compressive strength of concrete and to reduce significantly its permeability. The unique properties of condensed silica fume can also be used advantageously in grouts if condensed silica fume is used in combina-tion with a superplasticizer. The very fine silica particles give stability to the grout, there is no sedimentation of the cement particles and no bleeding. By adjusting the respective proportions of portland cement, of condensed silica fume,and of the superplasticizer a thixotropic grout can be made. The hardened grout is stronger and less porous when it contains condensed silica fume because the lime liberated during the hydration of portland cement reacts with the very fine silica particles to form a compact secondary CSH. By this way the possibility of leaching out of the lime is practically suppressed and the resistance of the grout to chemical attack should be improved.
10.14359/6334
SP83-02
Luigi P. Gonano and John C. Sharp
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.
10.14359/6335
SP83-03
Della M. Roy, M. Perez, B.E. Scheetz, and P.H. Licastro
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.
10.14359/6336
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