Horizontal Foundation Cracks Above Grade

Expansive Soil Problems and Solutions. Expansive soil, also called shrink swell soil, is a very common cause of foundation problems. Depending upon the supply of moisture in the ground, shrink swell soils will experience changes in volume of up to thirty percent or more. Foundation soils which are expansive will heave and can cause lifting of a building or other structure during periods of high moisture. Wet basements run the risk of growing mold. Discover a few simple, lowcost steps to drying out a wet basement from the experts at This Old House. You do your annual inspection and see the dreaded foundation crack. See why cracks occur, what to do to repair them what you should watch for. T i p s o n S caffold Sa fet y These tips and suggestions are designed to promote safety in the use of steel scaffolding. They are intended to deal only with some. Conversely during periods of falling soil moisture, expansive soil will collapse and can result in building settlement. Either way, damage can be extensive. Expansive soil will also exert pressure on the vertical face of a foundation, basement or retaining wall resulting in lateral movement. Shrink swell soils which have expanded due to high ground moisture experience a loss of soil strength or capacity and the resulting instability can result in various forms of foundation problems and slope failure. Expansive soil should always be a suspect when there is evidence of active foundation movement. In order for expansive soil to cause foundation problems, there must be fluctuations in the amount of moisture contained in the foundation soils. If the moisture content of the foundation soils can be stabilized, foundation problems can often be avoided. A major structural problem with your home is probably every homeowners worst nightmare. Find information about how foundation problems can effect the value of. BEST MANAGEMENT STANDARDS FOR FOUNDATION REPAIR JUNE 2012. These Standards were prepared by a licensed State of Wisconsin registered structural engineer. A foundation is defined as the basis on which a thing stands, is founded, or is supported any part of a structure that serves to transmit the load to the earth or. I will be following up on this concept a bit later. Clay Structure the Molecular Sandwich. UP/images/story/2012/87761937.jpg' alt='Horizontal Foundation Cracks Above Grade' title='Horizontal Foundation Cracks Above Grade' />The expansion potential of any particular expansive soil is determined by the percentage of clay and the type of clay in the soil. Clay particles which cause a soil to be expansive are extremely small. Their shape is determined by the arrangement of their constituent atoms which form thin clay crystals. Clays belong to a family of minerals called silicates. The principal elements in clay are silicone, aluminum and oxygen. Silicone atoms are positioned in the center of a pyramid structure called a tetrahedron with one oxygen atom occupying each of the four corners. Aluminum atoms are situated in the center of an octahedron with an oxygen atom occupying each of the eight corners. Because of electron sharing, the silicon tetrahedrons link together with one another to form thin tetrahedral sheets. The aluminum octahedrons also link together to form octahedral sheets. The actual clay crystals are a composite of aluminum and silicon sheets which are held together by intra molecular forces. There are many other elements which can become incorporated into the clay mineral structure such as hydrogen, sodium, calcium, magnesium, sulfur, etc. The presence and abundance of various dissolved elements or ions can impact the composition and behavior of the clay minerals. For a group of prominent and highly expansive clay minerals called smectites, one octahedral sheet is sandwiched between two tetrahedral sheets to create the mineral structure. In expansive clay, groupings of the constituent clay crystals will attract and hold water molecules between their crystalline sheets in a sort of molecular sandwich. Water Dipoles. Water molecules consist of two hydrogen atoms sharing electrons with a single oxygen atom. Mahjong Para Windows Vista Descargar Gratis here. The water molecule is electrically balanced but within the molecule, the offsetting charges are not evenly distributed. The two positively charged hydrogen atoms are grouped together on one side of the larger oxygen atom. The result is that the water molecule itself is an electrical dipole, having a positive charge where the two hydrogen atoms are situated and a negative charge on the opposite or bare oxygen side of the molecule. The electrical structure of water molecules enable them to interact with other charged particles. The mechanism by which water molecules become attached to the microscopic clay crystals is called adsorption. Age Of Empires 3 Full Version For Pc Windows 8. Because of their shape, composition and resulting electrical charge, the thin clay crystals or sheets have an electro chemical attraction for the water dipoles. The clay mineral montmorillonite, which is the most notorious in the smectite family, can adsorb very large amounts of water molecules between its crystalline sheets and therefore has a large shrink swell potential. When potentially expansive soil becomes saturated, more and more water dipoles are gathered between the crystalline clay sheets, causing the bulk volume of the soil to increase or swell. The incorporation of the water into the chemical structure of the clay will also cause a reduction in the capacity or strength of the soil. During periods when the moisture in the expansive soil is being removed, either by gravitational forces or by evaporation, the water between the clay sheets is released, causing the overall volume of the soil to decrease or shrink. As the moisture is removed from the soil, the shrinking soil can develop gross features such as voids or desiccation crack. These shrinkage cracks can be readily observed on the surface of bare soils and provide an important indication of expansive soil activity at the property. Magic Powder. Expansive clays have the ability to generate tremendous pressure on structures such as concrete foundations. These high pressures are the key to the destructive power of expansive clay in creating foundation problems. I have heard that these pressures can be on the order of 1. I have a quick story to illustrate the kind of pressure we are talking about. A number of years ago I built a custom home for my brother the lawyer. He wanted a big pad graded on his hillside lot and when I couldnt talk him out of it, I hired an Indiana man named Marion to do the grading. In order to avoid foundation problems, we were required to over excavate so that we could put down a uniform layer of fill. Marion started in with a big track loader but only a few feet down he started uncovering some rocks that wouldnt budge. Marion was game to try removing the rock and he went at it with tremendous zeal. Unfortunately, he might as well have been trying to move the Rock of Gibraltar. This was not Indiana limestone it was California blue granite. We then considered using dynamite but soon discovered a less dramatic solution we had holes drilled in the rock, poured in a magic powder and added water. The next morning the massive granite rocks lay split wide open. The main ingredient in the magic powder was a silicate with oxides of calcium, silicone and aluminum in other words expansive clay Expansion Potential. Potentially expansive soils which can cause foundation problems are identified by soils engineers by measuring the percentage of fine particles in a particular sample. If over 5. 0 of the particles in a sample are able to pass through a number 2. Cdc Serial Driver Windows Xp on this page. Regardless of the percentage of fines in a particular sample, a significant presence of clay minerals in a sample can indicate a possible expansive soil problem. Clay particles are generally considered to be smaller than silt particles but the true distinction between the two has more to do with origin and shape. Silt particles are products of mechanical erosion and could actually be viewed as very small sand particles. Clay particles are products of chemical weathering and are characterized by their sheet structure and composition. In order to determine the potential expansion of soils on a particular property, a soils engineer will take representative samples at the jobsite and return them to the lab for testing. Clay soils are often tested to determine their plasticity index. The plasticity index is a measure of the range over which the clay sample will retain its plastic characteristics.