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<p>Soil stabilization plays a crucial role in road construction, enhancing the engineering properties of natural soil and providing a stable foundation for roads. There are two primary soil stabilization methods: mechanical and chemical.</p>
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<h3 class="wp-block-heading">Mechanical Stabilization in Road Construction</h3>
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<p>Mechanical stabilization involves mixing various grades of soil to achieve a desired grade and improve stability by altering the particle size distribution.</p>
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<h3 class="wp-block-heading">Chemical Stabilization in Road Construction</h3>
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<p>Chemical stabilization involves the treatment of soil with chemical agents to enhance its properties. Common agents include Portland cement, lime, and asphalt binders.</p>
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<h4 class="wp-block-heading">Cement Stabilization in Road Construction</h4>
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<p>Cement stabilization is a technique that combines water, soil, and Portland cement, which is then mixed and compacted to create a high-density layer. Generally, 5% to 14% of Portland cement by volume is used. Most soils, except organic soils and soils containing sulfates, can be stabilized using Portland cement.</p>
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<p><strong>Steps in Cement Stabilization:</strong></p>
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<li><strong>Pulverize the Soil:</strong> Thoroughly pulverize the soil before mixing it with cement. The existing roadway material is scarified to the required depth if it’s to be used.</li>
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<li><strong>Mix Cement with Pulverized Soil:</strong> The required amount of Portland cement is mixed with pulverized soil, either on the road or in a central plant. In road mixing, cement is delivered in bulk and spread uniformly, while in plant mixing, the soil is mixed with cement and water in a controlled environment.</li>
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<li><strong>Compact the Mixture:</strong> Compaction should occur promptly before the mixture sets. For road mixing, compaction should be completed within one hour, while plant-mixed material allows up to two hours.</li>
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<li><strong>Cure the Layer:</strong> To prevent moisture loss, a thin layer of bituminous material, such as RC-250 or MC-250, is applied.</li>
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<h4 class="wp-block-heading">Lime Stabilization in Road Construction</h4>
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<p>Lime stabilization is one of the oldest methods used in road construction to improve soil properties. It’s effective for both base and sub-base stabilization. Materials commonly used include calcium hydroxide and dolomite.</p>
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<p><strong>Steps in Lime Stabilization:</strong></p>
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<li><strong>Cation Exchange:</strong> Adding lime to fine-grained soil initiates cation exchange, replacing sodium and potassium with calcium and magnesium, which reduces the soil’s tendency to swell with moisture increase.</li>
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<li><strong>Ensure Desired PI Values:</strong> Most suitable clayey materials should have a PI value less than 10.</li>
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<li><strong>Analyze and Mix Correctly:</strong> The quantity of lime is determined based on reducing plasticity and increasing soil strength, often between 3% to 10% by dry weight of the soil.</li>
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<p><strong>Carbonation Prevention:</strong> Ensure the stabilized layer does not dry out during hardening to prevent surface loosening from carbonation.</p>
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<h4 class="wp-block-heading">Asphalt Stabilization in Road Construction</h4>
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<p>Asphalt stabilization aims to waterproof and bind natural materials, improving soil durability and cohesion.</p>
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<p><strong>Steps in Asphalt Stabilization:</strong></p>
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<li><strong>Waterproofing:</strong> This helps maintain water content and reduce surface water penetration, protecting the subgrade from moisture increase.</li>
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<li><strong>Soil Mixing:</strong> The mixing of soil with asphalt binders can be performed in a plant or roadside. Plant mixing automates the combination of water and bituminous materials, while road mixing uses rotary speed mixers.</li>
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<li><strong>Layer Spreading and Compaction:</strong> The mixture is spread evenly in uniform layers and compacted thoroughly using suitable rollers.</li>
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<p>Soil stabilization in road construction ensures a durable and reliable road infrastructure, utilizing techniques like cement, lime, and asphalt stabilization to improve soil properties and ultimately enhance road safety and longevity.</p>
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