A parameter often used to evaluate the permeability of a porous system is the coefficient of water permeability (k) (a physical quantity that is a function of the global intercommunicating porosity of the system and, above all, of the pore size distribution that characterizes it).
It has been stated above that the granulometric requirement, although a necessary condition, is not a sufficient condition to guarantee the correct injection of a microdispersed suspension in a porous system; it is in fact necessary, among other things, that two other requirements of a more granulometric type, but rheological and Pipe Camera Rental are vital.
The low viscosity of the suspensions is required by the need to perform the intrusion in the system to be consolidated in a short time and with pumping pressures necessarily lower than those of mechanical failure of the system itself. Within certain limits the viscosity can be lowered by acting on the water/binder ratio, ie by operating with higher ratios (1 ≤ A/L <4) or by using appropriate fluidizing agents, especially required at the lower values of the aforementioned ratio.
The solid particles homogeneously dispersed in an aqueous suspension, if left in a resting state, tend to sediment under the action of gravity, separating a practically pure supernatant aqueous phase. The ratio between the volume of water thus separated and the total volume of the mixture defines the% of sedimentation, a parameter that is used as an index of the instability of a suspension as shown by Pipe Camera Rental.
On the other hand, the stability of a suspension corresponds to its intrinsic ability to keep all phases of it homogeneously dispersed, in a state of rest and under the action of gravity alone.
The instability of a suspension has a negative effect on its ability to consolidate a porous system, since the volume of really consolidated voids will not be the one corresponding to the volume of injected mixture, but only that corresponding to its sedimented fraction, ie the one complementary to the % of sedimentation.
There is a clear difference in stability between the suspensions of the microcement and those of the 525 Portland cement with the same water/binder ratio; the stability of the suspensions decreases with the increase of the water/binder ratio and with the decrease of the fineness of the dispersed phase. To improve the stability of the suspensions, especially those characterized by higher A/L ratios, suitable suspension additives can be used which significantly reduce the sedimentation.
However, these agents must be ecologically compatible with the system to be consolidated and chemically compatible with the microfine binder.