Strength and mechanical behavior of short polypropylene fiber reinforced and cement stabilized clayey soil

It is well known that organic matter may affect the cementing process in soils, but what happens when cement is added to an organic soil? Both the organic matter content and the nature of this orga...

Influence of the nature of organic compounds on fine soil stabilization with cement

We propose a new view on yield stress materials. Dense suspensions and many other materials have a yield stress—they flow only if a large enough shear stress is exerted on them. There has been an ongoing debate in the literature on whether true yield stress fluids exist, and even whether the concept is useful. This is mainly due to the experimental difficulties in determining the yield stress. We show that most if not all of these difficulties disappear when a clear distinction is made between two types of yield stress fluids: thixotropic and simple ones. For the former, adequate experimental protocols need to be employed that take into account the time evolution of these materials: ageing and shear rejuvenation. This solves the problem of experimental determination of the yield stress. Also, we show that true yield stress materials indeed exist, and in addition, we account for shear banding that is generically observed in yield stress fluids.

An attempt to categorize yield stress fluid behaviour

The objective of this study was to evaluate the effectiveness of self-cementing fly ashes derived from combustion of sub- bituminous coal at electric power plants for stabilization of soft fine-grained soils. California bearing ratio CBR and resilient modulus Mr tests were conducted on mixtures prepared with seven soft fine-grained soils six inorganic soils and one organic soil and four fly ashes. The soils were selected to represent a relatively broad range of plasticity, with plasticity indices ranging between 15 and 38. Two of the fly ashes are high quality Class C ashes per ASTM C 618 that are normally used in Portland cement concrete. The other ashes are off-specification ashes, meaning they do not meet the Class C or Class F criteria in ASTM C 618. Tests were conducted on soils and soil-fly ash mixtures prepared at optimum water content a standardized condition, 7% wet of optimum water content representative of the typical in situ condition in Wisconsin, and 9-18% wet of optimum water content representative of a very wet in situ condition. Addition of fly ash resulted in appreciable increases in the CBR and Mr of the inorganic soils. For water contents 7% wet of optimum, CBRs of the soils alone ranged between 1 and 5. Addition of 10% fly ash resulted in CBRs ranging between 8 and 17 and 18% fly ash resulted in CBRs between 15 and 31. Similarly, Mr of the soil alone ranged between 3 and 15 MPa at 7% wet of optimum, whereas addition of 10% fly ash resulted in Mr between 12 and 60 MPa and 18% fly ash resulted in Mr between 51 and 106 MPa. In contrast, except for one fly ash, addition of fly ash generally had little effect on CBR or Mr of the organic soil.

Stabilizing Soft Fine-Grained Soils with Fly Ash

Clayey soils are usually stiff when they are dry and give up their stiffness as they become saturated. Soft clays are associated with low compressive strength and excessive settlement. This reduction in strength due to moisture leads to severe damages to buildings and foundations. The soil behavior can be a challenge to the designer build infrastructure plans to on clay deposits. The damage due to the expansive soils every year is expected to be $1 billion in the USA, £150 million in the UK, and many billions of pounds worldwide. The damages associated with expansive soils are not because of the lack of inadequate engineering solutions but to the failure to identify the existence and magnitude of expansion of these soils in the early stage of project planning. One of the methods for soil improvement is that the problematic soil is replaced by suitable soil. The high cost involved in this method has led researchers to identify alternative methods, and soil stabilization with different additives is one of those methods. Recently, modern scientific techniques of soil stabilization are on offer for this purpose. Stabilized soil is a composite material that is obtained from the combination and optimization of properties of constituent materials. Adding cementing agents such as lime, cement and industrial byproducts like fly ash and slag, with soil results in improved geotechnical properties. However, during the past few decades, a number of cases have been reported where sulfate-rich soils stabilized by cement or lime underwent a significant amount of heave leading to pavement failure. This research paper addressed the some fundamental and success soil improvement that used in civil engineering field.

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Fundamentals of soil stabilization

The method of soil stabilization is well known and has been used throughout the world for many decades to improve some soil properties. Although many researchers have studied the effect of adding a...

Hélène Tremblay

Papers

Influence of the nature of organic compounds on fine soil stabilization with cement

Mechanical improvement and vertical yield stress prediction of clayey soils from eastern Canada treated with lime or cement