Browsing by Subject "Soil stabilization"
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Item Influence of grout mix design and placement procedures on the integrity of installed soil nails(Texas Tech University, 2004-12) Turner, John BThe evolution of methods to stabilize vertical soil walls includes a technique referred to as soil nailing. This technique utilizes steel tendons embedded in cementitious grout to bind a consolidated soil mass together sufficiently to prevent sloughing of the soil mass as its face is excavated. This thesis summarizes an effort to determine the factors related to the grout and its installation which affect wall stability. This research found that proper installation of grout materials will occur only where the grout is placed using a tremie pipe or grout tube which reaches the full length of the soil nail tendon. Additionally, this study shows that grout consistency can be selected to suit the installer and that, installed properly, any grout of sufficient strength which can be pumped using a general purpose concrete or grout pump should properly fill the soil nail borehole and embed the tendon.Item Influence of moisture content in granular bases on pavement performance(Texas Tech University, 1998-08) Hossain, Md. MosharrafNot availableItem Monitoring and performance evaluation of a road reconstruction project with lime stabilized fine-grained subgrade(Texas Tech University, 1997-05) Wright, Norman EdwardThe use of lime as a soil stabilizer is well documented in the literature. From a historical view point, the first project in modern times which used lime was built in 1948 at Fort Sam Houston in Texas. Army roadways had failed and needed to be reconstructed within a limited budget. Lime was used as a cost effective measure and mixed with the existing roadways. The Army constructed the two block section of roadway while the Texas Highway Department conducted the initial laboratory tests (National Lime Association, 1977). Because of the success of the initial project, both the Army and Texas Highway Department have used lime for soil stabilization.Item Sulfate Induced Heave: Addressing Ettringite Behavior in Lime Treated Soils and in Cementitious Materials(2012-02-14) Kochyil Sasidharan Nair, Syam KumarCivil engineers are at times required to stabilize sulfate bearing clay soils with calcium based stabilizers. Deleterious heaving in these stabilized soils may result over time. This dissertation addresses critical questions regarding the consequences of treating sulfate laden soils with calcium-based stabilizers. The use of a differential scanning calorimeter was introduced in this research as a tool to quantify the amount of ettringite formed in stabilized soils. The first part of this dissertation provides a case history analysis of the expansion history compared to the ettringite growth history of three controlled low strength mixtures containing fly ash with relatively high sulfate contents. Ettringite growth and measurable volume changes were monitored simultaneously for mixtures subjected to different environmental conditions. The observations verified the role of water in causing expansion when ettringite mineral is present. Sorption of water by the ettringite molecule was found to be a part of the reason for expansion. The second part of this dissertation evaluates the existence of threshold sulfate levels in soils as well as the role of soil mineralogy in defining the sensitivity of soils to sulfate-induced damage. A differential scanning calorimeter and thermodynamics based phase diagram approach are used to evaluate the role of soil minerals. The observations substantiated the difference in sensitivity of soils to ettringite formation, and also verified the existence of a threshold level of soluble sulfates in soils that can trigger substantial ettringite growth. The third part of this dissertation identifies alternative, probable mechanisms of swelling when sulfate laden soils are stabilized with lime. The swelling distress observed in stabilized soils is found to be due to one or a combination of three separate mechanisms: (1) volumetric expansion during ettringite formation, (2) water movement triggered by a high osmotic suction caused by sulfate salts, and (3) the ability of the ettringite mineral to absorb water and contribute to the swelling process.