Grouting works

The amount of drilling and grouting that will be required is approximate and the Contractor shall be entitled to no extra compensation above the unit prices bid in the schedule for this specification by reason of increased or decreased quantities of drilling and grouting work required, the time required, or the locations, depth, type or nature of foundation treatment. 

The actual grouting work specified herein shall be performed by a qualified Contractor with a minimum of five (5) years direct, continuous and recent experience in performing waterproofing chemical grouting work in similar conditions on at least six (6) different projects. 

Payment for grouting work should be explicitly detailed. Methods will depend on the type of specifications and local practice. Typical of domestic practice is the following excerpt from a basement waterproofing spec for a West Coast power utility ... 

Table 7.12. Concrete/grouting works Coastal construction hazards and...

Typical uses include the production of non-dispersible underwater concrete and reduction of the accumulation of bleed water in mass concrete placed in deep forms. Consequently, AWAs are useful in mass concrete work because they prevent the formation of laitance on the surface of the concrete and thereby reduce the excessive cleaning between successive lifts. The admixtures also reduce the voids formed under horizontal reinforcing bars. Therefore, bond to steel increases and potential corrosion problems are reduced. The admixtures are also used in conjunction with WRAs in oil-well cementing grouts to reduce pipeline friction and rapid water loss and grouting of pre- and post-tensioned concrete ducts [47]. New valves and control devices under development in Europe and Japan used in conjunction with AWA will likely advance the field on underwater concrete. 

Grouting technologies have been commercially available for many years, however, new techniques are also being developed. In addition, there is considerable work being done to test the performance of alternative grouts in different subsurface environments using different installation techniques. 

As early as 1859 Wright mentioned the binding property of elementary sulfur (1), but up to the 1930s mixtures of sulfur and stone powders were used exclusively to grout foundation screws. The first references in the literature to the chemical and physical properties of sulfur mortar are found in the works by Duecker and Payne (2,3,4,5). The sulfur mortar described by them contained about 60 wt % sulfur and therefore only a small amount of aggregate. It was used as a sealing... 

There are four distinctly different types of Portland cement. Only types I and II are used for grouting, type I (often referred to as ordinary Portland cement), almost exclusively. Type II (high early strength cement) differs from type I primarily in its finer particle size. This provides more reactive surface area, and thus more rapid setting, often desirable in structural work. Grouters, however, are more interested in the finer particle size, which permits penetration into finer voids and cracks. Typical grading analysis of various cements are shown in Figure 9.1. 

Special equipment is needed to place compaction grout. Pumping pressures of up to 1000 psi may be needed, although most field work is done in the 400 to 600 psi range. Piping and hoses must be at least two inches in diameter. Pumping rates generally fall within 1 to 4 cubic feet per minute. 

Compaction grouting is often done to lift and level slabs and structures, as well as to prevent further settlement. Such work requires close control of the changing elevations, to prevent damage to the structure. 

The viscosities of four different grouts, as measured by a Stormer viscosimeter, are shown in Fig. 10.5. Viscosities, of course, vary with percent (dissolved) solids, and the chart is presented in that fashion. The usable viscosities of the various materials depend on the minimum desirable field concentration of solids. Thus, while it is obviously possible to work with a 20% sodium silicate solution in the Joosten process (a viscosity of between 3 and 4 cP), a gel would not form at that low a concentration, and it would be misleading to claim a 4 cP viscosity. In a similar fashion, other silicate formulations can be used to give either low viscosity of high strength, and it is misleading to list those values simultaneously as if they were the properties of the same fluid. 

Figure 10.5 Viscosities of several chemical grouts. Heavy lines indicate the concentrations normally used for field work. 

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