The primary raw material for lime production is natural rock (limestone, dolomite, chalk, etc.) with calcium carbonate as the main component. In addition to producing lime with natural raw materials, another source of lime is by-products of the chemical industry (such as calcium carbide slag when calcium carbide is used to produce calcium hydroxide, the main component of which is calcium hydroxide), that is, slaked lime.
Lime used in construction projects mainly includes building quicklime, building quicklime powder, and building slaked lime powder.
Calcium oxide
The main component is calcium oxide CaCo3; the white color contains impurities and is light gray or grayish-yellow. It is usually used with slaked lime in dry-mixed mortar products to increase the plasticity, constructability, and bonding strength of dry-mixed mortar. Slowly carbonizing in lime mortar plastering can enhance surface strength. Like slaked lime, the dosage should not be too high. Quicklime containing impurities and insufficient fineness will cause pulp explosion due to indigestion.
Calcium carbonate
The main component is CaCo3 with two kinds: natural and artificial. The former is called heavy calcium carbonate, and the latter is called light calcium carbonate.
Heavy calcium carbonate is made by crushing the ore after selection, then dry grinding or wet grinding into powder, and then filtering, drying, and crushing. It is rough in texture, high in density, insoluble in water, soluble in acid, releases carbon dioxide, and can be used as a filler for building waterproof coatings. It is made by mechanical crushing, grinding, and sieving. Heavy calcium with high purity and whiteness is usually crushed and ground from the scraps of pure white marble. The calcium content is as high as 95%, the quality is stable, and the effect is good.
Heavy calcium carbonate is the main filler of putty in dry-mixed mortar products, which has anti-grinding and specific hiding power. It is also one of the essential fillers in architectural coatings.
Light calcium carbonate is processed from natural limestone and calcined into calcium oxide first and then made into a suspension of lime milk, next fed into Co2 to precipitate into calcium carbonate precipitate, filtered, dried, and dried crushed for the finished product.
Light calcium carbonate has fine particles, is insoluble in water, and is slightly alkaline. It should not be used with pigments that are not resistant to alkali. It is widely used as a filler in architectural waterproof coatings.
Calcium carbonate is a slightly soluble substance. Therefore, the effect of choosing calcium carbonate in the waterproof coating is similar to using quartz powder. The difference is that calcium carbonate is a weakly polar substance with a specific activity in forming polymer cement waterproof coatings. This is mainly reflected in the weak buffering property, which can adjust the pH value, thereby adjusting the hydration speed of cement and the forming process of the waterproof coating film.
