Effective Soil Stabilization for Stronger Foundations
Recently, we got an opportunity to look at a couple particular projects using gunnite as a method of soil stabilization. You can basically think of gunite as concrete that’s applied by spray. Spraying concrete requires an incredibly heavy and strong type of pump and hose rig setup. Concrete is simply heavy, in almost any form, even with a variety of different admixtures to make it flow and stick better. Even air entrained concrete or concrete mixed with insulative type materials, while lighter than typical concrete, is still very heavy. Therefore, it takes a very large and powerful type pump and set up to actually eject concrete like this through a nozzle type gun that sprays it through the air.
These projects are interesting, not only because of the large scale, but they are executed relatively quickly at a relatively low cost. All these things are comparative because even though we say they’re relatively “low cost”, they are still extremely expensive but more because of their scale and less because of the efficacy of the methodology. In fact, overall, it’s a relatively or comparatively efficient method of installing a massive type of retaining wall. This is not a actual retaining wall, but it has similar properties and works in similar ways.
The hillside in the picture below is at over a 65° angle at some of the steepest points.
Often, when we’re talking about geotechnical type of design and support, we consider the conditions of repose. The natural repose of soils repeatedly shows that soil will generally and naturally reposition themselves over time. Different types of soils will reposition at different angles or slopes. Sand, for example, will often reposition itself to a 30 to 35° angle.
We provide this detail in an approximate range because it’s not precise and depends on several variables. The moisture content of the sand can increase the angle of repose significantly, to a point. (Beyond a certain point, when sandy soils are overly hydrated, the sand can become slurry and actually significantly increase the amount of repose.) Also, the particle size and shape will also affect the angle of repose. Larger particles with sharper angles will have a higher degree of reproach, in most cases.
Like many types of landforms, over time, this particular hill will eventually erode and wash out and or even collapse in parts or slide off into the roadways below. In cases where construction and development is happening and or things are being built at the base of land masses with significant incline or slope, it can be important to stabilize the soil. Typically, when we talk about the everyday type of masonry restoration that applies to retaining walls, such as tuck pointing into a repointing, we’re generally referring to retaining walls that are built to transition between different grades.
Often the near horizontal surfaces of these near planar land areas, there will either be landscaped or hardscaped terraces as part of the overall stabilization. Commonly we work on properties like that here in Washington DC. Often, even being familiar with the particular nuances of individual properties, you can pick up on what areas have more hills and dramatic grades just by driving down the street. Where there are often slopes in the streets, there will often be similar slopes in the adjacent properties.
In the pictures above and below, you can see examples of weeps that have been installed at this area of gunite. You can see the gunite has a relatively rough texture, in some cases, gunite can be treated and even smoothed or screeded after it is shot from the application rig or gun. Here though, the rough texture of the concrete is left untouched and raw.
The next picture below shows that rough surface more closely.
We can Help
Our company focuses on historic restoration more than modern building upkeep, maintenance, and construction, but our company understands both types of construction very well and a full picture well-rounded approach is needed in any niche in the construction industry. Although we focus on historic restoration, repointing, tuckpointing and historic brick repair, our company also has technical knowledge and competencies in the areas of modern and contemporary construction as well as we become one of the leaders in that area of the market today. Understanding both historic and modern or contemporary construction is useful because both aspects help understand the challenges and potential solutions for challenges in building science and construction.
We can help with a variety of historic masonry restoration needs and upkeep, from modest tuckpointing and or repointing to complicated and extensive historic masonry restoration. Infinity Design Solutions is a historic restoration specialist contractor specializing in both historic masonry restoration such as tuckpointing our repointing, and brick repair. If you have questions about the architectural details or facade of your historic building in Washington DC, reach out and say hello and if we can help we’ll be glad to assist you. You can email us or call us on the telephone at the following link: contact us here.
