CHAPTER 3
CLAY SOIL STABILIZATION
Treatment procedures that are available for stabilizing expansive soilsinclude:
• Prewetting:
Prewetting is based on the theory that increasing the moisture content in theexpansive foundation soils will cause heave to occur prior to constructionand thereby eliminate problems afterward (Chen, 1975).
• Moisture Control:
Moisture control methods are applied around the perimeter of structures inan attempt to minimize edge wetting or drying of foundations (Das, 1990).
• Soil Replacement:
Removal of expansive soils and replacement with nonexpansive soils is onemethod to provide stable foundation material (Nelson and Miller, 1992).
• Compaction Control:
Expansive soils expand very little when compacted at low densities and highwater contents, but expand greatly when compacted at high densities andlow water contents ( Abduljauwad, 1993; Chen, 1975).
• Chemical Stabilization:
Chemical additives, such as lime, cement, fly ash, and other chemicalcompounds, have been used in soil stabilization for many years at various degrees of success. The effectiveness of these additives depends on the soilconditions, stabilizer properties, and type of construction (i.e. houses, roads, etc.). The selection of a particular additive depends on costs, benefits,availability, and practicality of its application (Al-Rawas et al. 2002).
Wood ash was used to stabilize the clay soilin this study and a few in quantity of lime is also used in this study.
3.1 Wood Ash
These are soils consisting predominantly of unaltered mineral material that have no surface/sub-surface horizon attributed to soil forming processes (unless buried under a 730cm thick deposit from the Holocene) (Avery, 1980;). These soils do not normally have continuous vegetation cover (Avery, 1980). They occur in very recently formed soil and may have a superficial organic or organo-mineral layer less than 5cm thick. Sometimes they have a buried horizon below 30cm of depth. (Thompson, 2007; Jarvis, 1984).
Vertisols can be used as soils for foundations of buildings. However, the foundation has to possess a wiggle room to let the foundation move easily along the earth. However, the foundation is made too tight then there might be some future consequences. An example is the Houston Black soil located between the red river and San Antonio.
Loose soil from digging animals is easier for plants to grow in compared to the hard compacted soil found where there are no digging animals
It may seem like we will never run out of soil, but soil conservation is a critical issue in Texas today. So if the entire farming community implemented at least one type of soil conservation effort we would widely improve our agriculture benefits. These benefits would include saving energy, by using less diesel fuel for tractors. Implementation of these farming practices could save water and reduce several types of diseases and pests that farmers encounter when planting their crops. This is no time to be cutting corners on expenses because the United States spends about $37.6 billion each year on soil
Franklin D Roosevelt once said, “the history of every Nation is eventually written in the way in which it cares for its soil.” The United States began seeing sustainable management practices in farms, and healthier soil through this act. In 1982 through 2007, the United States soil erosion had declined by 43%” (Montanarella, 2015). Every year the United States loses about $400 billion dollars due to crop soil that is eroded. Soil is a limited resource and the largest resource for growing food, accommodating diverse ecosystems, and providing food resources. Therefore laws, acts, and provisions are necessary to protect this natural resource.
While all ethics involved are important, this one might be the most critical, due to the strong reliance we have on the natural Earth cycles in permaculture. Soil repairing and building is a great technique that we spent a lot of time on during this course and one that Bane speaks highly of (Bane, 2012, p. 28). This practice caters to EarthCare by rehabbing the land we are able to improve the Earth, as well as improve our own yields and benefits.
Believe it or not, the soil around your home in New Braunfels will have an impact on its foundation. You have three key factors that will determine the amount of pressure. First, it depends on the types of soils that you have around your foundation. Second, it depends on the moisture of the soil. Finally, the pressure will depend upon how deep the foundation has been dug. A deeper foundation tends to be better for areas with expansive soils because it reduce the pressure. Oshan Foundation Solutions has helped countless people over the years struggling with a crumbling foundation. We are professionals who understand the value of your time, which is why when we do an estimate, we will also give you a deadline.
Throughout central and southern Mexico, there are high rates of precipitation. Therefore with all the precipitation and solar energy, some of the richest soils are produced in the heart of Mexico. With these accommodations, mostly infertile yellowish soils are produced that are high in iron oxides and also aluminum hydroxide (“Mexico Geography and Climate”). These rich-in base soils are easily crumbled and are continuously farmed annually. But with the continuous farming with these soils, sheet erosion is starting to effect the soil and cause problems within the environment (“Encyclopedia of the Nations”).
If you have made some of the mistakes listed below, don't be too hard on yourself because unless you've completed a fair amount of research on the topic, any one of these oversights are easy to make. Before getting to them, some background information on expansive clay soil is necessary.
How has clay and more specifically its use, changed the world and the lives of people? Or rather what is clay? Some people think it’s just dirt, but is that really all it is? To find out we have to know more about clay. Its chemically composed of hydrous aluminum silicates, and sometimes it might have little amounts of iron, potassium, sodium, calcium, and magnesium. It´s also composed of dead plant, animal parts, including minerals. Nearly all the ingredients of soil. Over time water breaks up all the plants, animals, and minerals, pulverizing it deep in the ground, and the bigger particles are removed through the rocks and sand. Leaving behind silt to over time become beds of clay. With this composition, clay becomes a useful and unique substance
Soil amendments may need to be made depending on what you want to grow and what your soil test reveals. Lime or sulfur can be added to raise or lower pH respectively. Gypsum, perlite, vermiculite, and sand can be added to improve aeration, drainage, or moisture retention. Peat moss or compost can be added to improve fertility and soil structure over time. All of these amendments can be purchased at your local garden store; just remember to follow label directions to avoid over-amending your soil and causing conditions unfavorable for plant growth.
If the soil is too weak to take even a small height of embankment vacuum preloading can be used. In this method to accelerate consolidation settlement atmospheric pressure is used in spite of surcharge load.
The secondary compression for over consolidated soil is much smaller than that of normally consolidated soil. The secondary settlement can be reduced or even eliminated either by increasing the time of temporary overloading or by using a heavier overload.
There are many correlations that are useful in identifying potentially expansive soils. It may also be possible to identify them
Microbial Induced Calcite Precipitates (MICP) is a new and sustainable technology used to improve the properties of construction materials. This technique works by introducing bacteria solution (e.g., Sporosarcina pasteurii, B. megaterium, Spoloactobacilus, Clostridium and Desulfotomaculum) into the soil matrix, and then injection of a chemical solution consisting of urea and one of calcium salts (e.g., calcium chloride and calcium acetate) into the soil matrix several times.