Hydrated Lime (Calcium Hydroxide) is a white powder that forms alkaline aqueous solutions. Hydrated Lime is used in water treatment, asphalt, mortar and plaster, and pulp and paper industry. It is used as a flocculent in water and wastewater treatment and adjusting pH. In the paper industry, Hydrated Lime is an intermediate in the causticizing step of making pulp.
The combination of calcium hydroxide mixed with activated carbon has several important applications in environmental and industrial applications; air pollution control, water treatment, soil stabilization, and carbon capture. In air pollution control the mixture can be used in flue gas treatment to remove acidic gases such as sulphur dioxide (SO2) and Hydrochloric acid (HCl). The activated carbon aids in adsorbing heavy metals and dioxins, while the hydrated lime neutralizes the acidic gases. In soil stabilization hydrated lime improves the soil's physical properties and the activated carbon serves in adsorbing any organic pollutants present. Hydrated lime can be used in processes like calcium looping for capturing carbon dioxide (CO2) from industrial emissions, while the activated carbon in the mix can enhance the CO2 capture efficiency.
In construction, Hydrated Lime is an additive in asphalt, which improves cohesion and retards the aging process. It is a component of many building products, including mortar and plaster. Hydrated lime particles form polar molecules that intercept and deflect cracks by reducing the rate of oxidation and aging in asphalt. Numerous road departments throughout North America have found that incorporating 1% to 2% hydrated lime mass into hot-mix asphalt add years to the life of a highway making the addition very cost effective. The hydrated lime reduces stripping, rattling, cracking, and aging of the pavement.
The Hot Mix Asphalt Mixtures (HMA) with hydrated lime reduces the moisture damage and stripping of aggregates sensitive to moisture. The Lime reduces the design asphalt content; improves toughness and resistance to fracture growth at low temperatures; reduces age hardening of the asphalt binder; and increases mixture stability and durability based on the literature in North America. See attached TDS, SDS, and HMA/Lime Literature with three academic papers: 1. How to Add Hydrated Lime to Asphalt - An Overview of Current Methods by National Lime Association Sept., 2003. 2. The Benefits of Hydrated Lime in Hot Mix Asphalt updated by Peter E. Sebaaly 2006 and 3. Using Hydrated Lime in Hot Mix Asphalt Mixtures in Road Construction by G. Kollaros, E.Kalaitzaki, and A. Athanasopoulou in 2017.
