Lime (material)

Lime Composition and Sources Lime is primarily composed of calcium oxides and hydroxides, recognized as a mineral with the chemical formula CaO. Originating from its use in building mortar, lime is sourced from rocks like limestone, chalk, marble, coral, sea shells, calcite, and ankerite. It finds extensive applications in building materials, engineering, chemical feedstocks, sugar refining, and wastewater treatment. Production and Uses of Lime Lime is produced by slaking quicklime with water to create hydrated lime. Common uses include binding mortar in masonry works, whitewashing walls, and in building materials like lime mortar, plaster, render, concrete, and limestone blocks. The qualities of lime products are influenced by factors such as composition, slaking method, and curing process, affecting characteristics like workability, bond strength, setting time, and resistance to sulfates. Lime Cycle and Building Materials Classification The lime cycle involves the conversion of limestone to quicklime by heating, then to slaked lime by hydration, and back to calcium carbonate by carbonation. Lime used in building materials is classified as pure, hydraulic, or poor lime, which can be natural or artificial. Different types of lime are used in various applications like lime mortar, plaster, render, concrete, and whitewash, each with specific qualities influenced by factors like workability, bond strength, setting time, and hydraulicity. Types of Lime in Building Materials Types of lime include pure lime, semihydraulic lime, hydraulic lime (natural and artificial), and poor lime, each with distinct characteristics and applications. Hydraulic lime is further categorized based on clay content and setting time, with varying strengths from feebly to eminently hydraulic. Mortars with different hydraulicity levels can be tailored for specific requirements like strength, durability, and workability. Specific Lime Varieties and Applications Type S hydrated lime, commonly used in the United States, is added to Portland cement to enhance plasticity and water retention. Kankar lime is derived from kankar, a form of calcium carbonate, while selenitic lime contains added gypsum plaster and is known for its quick setting properties. Roman concrete, a historic application of lime, utilized lime and volcanic ash to create durable concrete through a pozzolanic reaction, showcasing the longevity and sustainability of limebased materials.