Influence of Bentonite Cement on the Pumpability of Compaction Grouts


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Title: Influence of Bentonite Cement on the Pumpability of Compaction Grouts

Author(s): Roy Borden and Daniel M. Groome

Publication: Special Publication

Volume: 83


Appears on pages(s): 115-128

Keywords: admixtures; bentonite; compacting; grout; grouting; viscosity; workability.

Date: 10/1/1984

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.