Terrasil molecules are diluted in water at room temperature. When water enters Terrasil in contact with the soil, Terrasil molecules are attracted by the polar groups (Silanol Group) of the soil and remain attached until the water evaporates, at which time they form a chemical covalent bond by condensation. This bond (Siloxane) is extremely strong and does not revert in conditions of humidity, ultraviolet radiation or
temperature.
One see the aggregate is covered by hundreds of millions of hydrophobic molecules, the soil will be repellent to water, which has a very important effect on the characteristics of the soil.
Effect on maximum density and compaction
By adding TERRASIL to the compaction water, an extraordinary lubrication of the soil particles is produced, which present less friction between them, improving the redistribution of the particles and the efficiency of the compaction effort.
It is usual to achieve in work conditions densities of between 99%-103% of the maximum density achieved in the laboratory even in slightly different humidity conditions than the optimal compaction.
Effect on soil bearing capacity - CBR -UCS- MR
The reorganization of the particles resulting from the increased initial lubrication, the higher density and the fact that moisture cannot spread easily, produces significant increases in the soil’s bearing capacity, demonstrated in several articles and in multiple tests, regardless of the measurement method used.
CBR (California Bearing Ratio)
Depending on the dosage of the product and the type of soil, the increases in the support capacity measured by the CBR test increase between 200% and 400%, with the most extreme soils (CBR<4% and CBR>50%) showing the least gain.
In general, the CBR increases with the curing time.
Resilient Module (Mr)
The effect on the resilient module of stabilization with TERRASIL is very important and gains are obtained across the entire range of cyclic load confinement pressures even at reduced dosages of Terrasil (0.3-0.5 kg/m3).
The improvements in the resilient module have a significant impact on reducing thickness and improving the durability of the tracks.
According to the criteria of the AASHTO standard, any value higher than 40,000 psi (275 Mpa) for bases and sub-bases must be discarded for thickness reduction.
With TERRASILl it is relatively simple to achieve these maximum values in subbase and granular base.
Resilient module in subbase
In the following case a Mr of 70 Mpa (10.000 psi) becomes about 270 Mpa (39500 psi) with 0.4 kg/m3 of Terrasil.
Effect on the resilient module in granular bases
Terrasil significantly improves the resilient module (Mr) of the materials, as an example are indicated the material of a granular base.
It should be noted that although the increase in module obtained with Terrasil is greater, the design is limited to Mr of 40,000 psi so it does not reflect the full potential of the solution.
Unconfined Compression (UCS)
Since Terrasil is not a cementitious material, the unconfined compression test, especially in dryer, yields reduced increments (compared to cementitious stabilizers).
However, increments of at least 30%-100% can be expected depending on the cohesive or non-cohesive nature of the material.
The improvements in unconfined compression values are also dependent on the curing time of the samples and are observed both in Terrasil and in the combination of Terrasil with cement or lime.
Effect on permeability
With low dosages of Terrasil, the matric suction of the soil and the permeability in saturation is reduced, so the soil will remain below the saturation humidity (unsaturated condition) during the whole life of the track.
In the unsaturated condition, the soil behaves elastically, without suffering permanent deformation and, if the maximum acceptable load (designed from the Resilient Module) is adequate, the treated soil layer will not be fatigued.
Absorption by capillarity and free swelling is reduced or eliminated, provided that the floors have a free swelling of less than 20%, it will be possible to reach the no
swelling.
In addition to the lower absolute permeability, the permeability values in all humidity ranges are practically zero until saturation humidity is reached. Even in this case, the permeability coefficient is very low and equivalent to 0.01 cm / day.
Effect on other tests
In addition to the tests mentioned above, we have extensive and varied information on the effect of Terrasil on soils evaluated under other methods that seek to solve specific problems of a route and are briefly mentioned here:
Durability test of soil-cement
The durability test involves subjecting the samples to 12 moisture-abrasion cycles with a maximum loss of 2% of mass.
The soils treated with Terrasil and cement exceed the 12 cycles while soils only with Terrasil or only with cement cannot pass the test.
An untreated soil would not exceed the first cycle and a soil with cement would only exceed 4 cycles.
Indirect traction
It is a test that is performed on cohesive materials or in the presence of cement.
In general, TERRASIL not being a cementing agent should not increase the value of indirect traction and, however, if this effect has been observed both in soils with TERRASIL and in soils with TERRASIL and cement and in soils with TERRASIL and asphalt emulsion in low dosage.
In addition to the increase in indirect traction, a higher TSR (ratio between dry and immersion traction) is observed.
Marshall Flow and Stability
A soil with good grading combined with cement (1%-3%), Zycobond and Terrasil will have a higher bearing capacity than an asphalt mix while maintaining its flexibility characteristics and excellent resistance to moisture.
Estas capas de “Super Suelo” pueden usarse como sustitución de capas de base asfáltica y aportan una estructura excelente a la vía.
En estos casos, sugerimos ensayar la estabilidad de Marshall en inmersión en agua a 60ºC y comprobar su durabilidad con el tiempo.
Adicionalmente, se pueden realizar ensayos de fatiga como el ensayo de fatiga a flexión de viga en tres puntos, con el objetivo de asegurar su durabilidad en el tiempo.