Penetrability due to filtration tendency of cement-based grouts

TLDR: The possibilities of sealing structures are of great importance from both an economical and environmental point of view as discussed by the authors, and Grouting as a method of strengthening and sealing rock, soil and concrete is widely used.

About: This article is published in Tunnelling and Underground Space Technology.The article was published on 2008-07-01 and is currently open access. It has received 121 citations till now. The article focuses on the topics: Cement.

Figures

Figure 5.2, Ordinary-distribution plot of a grain curve.

Table 6.17, Results from the filtration experiments in the physical model.

Figure 5.9, Outline of the physical model (Saaidi, 2004).

Figure 5.3, Pictures taken in 1000x magnification. To the left, co and to the right fine grains.

Figure 6.47, Statistical analysis of the W/C ratio after filtration, as a function of type of cement. Predicted concerns the predicted W/C ratio of the mixture after the mixture has passed the slot according to eq 6.2.

Figure 6.48, Statistical analysis of the W/C ratio after filtration, as a function of type of superplasticisers. Predicted relates to the predicted W/C ratio of the mixture after the mixture has passed the slot according to eq 6.2.

Frequently asked questions

Q1. What is the reason why a grout has a better penetrability?

This phenomenon of decreased packing ratio of grains (increased porosity), is probably an important reason why grouts with a high W/C ratio have a better penetrability than a grout with lower W/C ratio.39 

Q2. What is the importance of a low yield and viscosity value of the grout mixture?

In order to achieve a good penetrability (filtration tendency and rheology) of the grout mixture, it is probable according to performed filtration tests, of importance to have a relatively low yield- and viscosity value of the mixture. 

Q3. What is the basic idea of using measurement methods for filtration tendency?

The basic idea of using measurement methods for filtration tendency is to identify the mesh or slot aperture when plug formation occurs at the mesh or slot entrance (measurement of the passed amount of mixture through the used slot or mesh aperture before plug formation occurs). 

Q4. What is the principle behind the rule of a thumb regarding soil grouting?

The behaviour for cake filtration and deep bed filtration has been the basic idea behind the rule of a thumb regarding soil grouting. 

Q5. How can the probability of a plug formation be evaluated?

In the current model the probability of plug formation near the slot entrance can be evaluated by using the grain concentration and the grain flow velocity as indicating parameters. 

Q6. What is the work of finding the parameters that influence the filtration tendency?

The work of finding essential parameters from the grain size and grain size distribution, that influence the filtration tendency is probably much a work of finding representable parameters to characterize the grain size and grain size distribution. 

Q7. What is the effect of a higher W/C ratio on the filtration tendency of cement?

According to performed tests the filtration tendency is more influenced by an increased W/C ratio in fine grained mixtures compared to mixtures containing coarser grains. 

Q8. What can be expanded and developed to improve the filtration tendency of grouts?

The performed filtration tests of grouts can of course be expanded and developed by using, for example, several other grain size distributions, other types of cements and other test equipment. 

Q9. Why is the grain size distribution more inclined to agglomerate at the crack entrance?

Due to difference in shape of grains in the mixture, it can be proposed that irregular (larger angularity) grain shapes are more inclined to agglomerate at the crack entrance than grains with a regular shape.•