Tuesday, January 17, 2012

Spur Ranch Rd, Explanation of the Curing Process

From: Michael McDermott
Organization: RoadPacker Group Ltd
Date: Mon, 16 Jan 2012 21:36:09 -0700
To: 'Bob Sherwin' <bob@thesherwingroup.com>
Subject: Spur Ranch Rd

Dear Bob,  Please pass this on to Jim, that he may send it to his residents. We have just returned from viewing the Spur ranch roadway after hours of continuous  rain and snow. You and I were also on the roadway at 8 am this morning to view the condition of the roadway after 14 hours of rain and snow that had fallen on to it. So let me lay out clearly what has happened here and give you my prognosis for the short and long term condition of the road.
Firstly the higher quality soil that were recently imported by you at a great cost in order to repair and improve the previous roadway has responded as I expected it to do. We have been able to achieve greater compaction level thus a higher level of impermeability making it more difficult for moisture/water to penetrate the stabilised soil.
When a clay based soil such as we have on the Spur Ranch Rd. is stabilised with the RoadPacker stabilisation products, the chemical activity that takes place is that the product works directly to remove the absorbed water within the clay particle and make it an adsorbed water solution attached to the clay particle ready for expulsion from the soil through a greater realignment of the clay particles as a result of super plasticisers that are added to the RoadPacker stabiliser formulations resulting in greater compaction of the soil and also increasing the impermeability of the treated/stabilised surface through compaction.
[See below for an additional explanation of absorption and adsorption. -Jim]
This means that when properly applied to a suitable soil for treatment, the RoadPacker Plus product will remove the moisture from the soil and increase the density of the soil. Once the stabilised/treated soil has been properly cured, the stabilised roadway will repel water from entering into the structure of any soil. This is evidenced by roads that we have in place in Canada, Russia, Northern China and many other Northern Hemisphere countries suffers winter freezing temperatures and which are still in place and working properly after 13 winters/springs of torrential rains and sub-zero (-20 to 40 c below) climatic conditions.
What we have here at Spur Ranch today is a soil that whilst strongly compacted and rendered impermeable to water/moisture, is a soil that is still in its infancy/initial stages of curing with a volume of moisture still trapped under the surface of the soil that has not yet been expelled by the chemical action of the RoadPacker Plus in relations to the mineralogy of the soil.
The normal curing period for a clay based soil treated with RoadPacker Plus is 5 to 6 days. During that time, the soil will de-hydrate at an elevated level/speed forcing hairline cracks to appear in the in the surface of the soil/roadway which have to be controlled by an application dosage of 1 part RP Plus to 1,000 parts water to slow down the speed of the cracking and bring the road/soil back to a closely sealed surface. This process requires that the roadway needs to be sprayed twice a day to achieve this.
What is happening here is that due to the freezing temperatures that we are seeing here in Santa Fe at the moment during both the day and throughout the night, we are having difficulty in letting the curing process take place effectively. Thus whilst the soil of the roadway is stabilised effectively and has increased dramatically in density, the surface of the soil still bears a small amount of moisture that we have not yet due to the continuous low seasonal temperatures, been able to dispel from the soil/roadway.
With the weather forecast showing higher temperatures for the remainder of the week and clear sunny weather, I am confident that we can complete the curing process to a point where the soil/roadway will in fact reach the point where is will repel any future rains and moisture from the surface and allow normal traffic operations on its surface.
We will first thing tomorrow, tidy up the 2 to 3  millimetres of loose surface material and allow the roadway to be re-compacted and incorporated into the already compacted and dense roadway that is already there. The remaining 2 or 3 sections already chemically treated but not yet compacted will be completed within the next 48 hours after we have dried out the existing soil.
I hope that this explanation gives you and your residents a clearer insight as to what is going on here. This technology works well be it must be allowed to cure properly to be effective.

Best regards,
Editorial Comment (Jim): For our road, adsorbed water refers to molecules of water that are bound to the surfaces of the clay particles by electrical forces. These forces are a result of the electrostatic attraction resulting from polarized electrical charges induced in both the water and the clay. (Recall that unlike charges attract.) In effect, the water molecules are stuck to the surfaces of the clay.

Absorbed water, by contrast, refers to molecules that diffuse into a material and mix with it. Absorption is thus a bulk process and not a surface process.

As Mr. McDermott explained above, the RoadPacker chemicals are designed to extract absorbed water from the bulk of the clay, and change it into adsorbed water that resides on the surface of the clay particles. In effect, this process squeezes out the water from the clay, which ultimately ends up on the surface of the road where it can evaporate. When that happens, the dirt/clay mix is very dense and impermeable to water. At least that’s the theory. We’ll wait and see what happens.


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