Dry powder mortar is a semi-finished mortar made of raw materials in the factory through accurate batching and uniform mixing. It can be used only by adding water and stirring at the construction site. Due to the variety of dry powder mortar, it is widely used. One of its biggest features is that its thin layer plays the role of bonding, decoration, protection and cushioning. For example, the mortar with the main bonding function mainly includes masonry mortar, mortar for wall and floor tiles, pointing mortar, anchoring mortar, etc.; the mortar with the main effect of decoration mainly includes various plastering mortars, putty for interior and exterior walls, and colored decorative mortar. etc.; waterproof mortar, various corrosion-resistant mortars, ground self-leveling mortar, wear-resistant mortar, thermal insulation mortar, sound-absorbing mortar, repair mortar, mildew-proof mortar, shielding mortar, etc. are used for protection. Therefore, its composition is relatively complicated, and it is generally composed of cementing material, filler, mineral admixture, pigment, admixture and other materials.
1. Binder
Commonly used cementing materials for dry mix mortar are: Portland cement, ordinary Portland cement, high alumina cement, calcium silicate cement, natural gypsum, lime, silica fume and mixtures of these materials. Portland cement (usually Type I) or Portland white cement are the main binders. Some special cements are usually required in the floor mortar. The amount of binder accounts for 20%~40% of the dry mix product quality.
2. Filler
The main fillers of dry powder mortar are: yellow sand, quartz sand, limestone, dolomite, expanded perlite, etc. These fillers are crushed, dried, and then sieved into three types: coarse, medium, and fine. The particle size is: coarse filler 4mm-2mm, medium filler 2mm-0.1mm, and fine filler below 0.1mm. For products with very small particle size, fine stone powder and sorted limestone should be used as aggregates. Ordinary dry powder mortar can be used not only crushed limestone, but also dried and screened sand as aggregate. If sand is of sufficient quality to be used in high-grade structural concrete, it must meet the requirements for the production of dry mixes. The key to producing dry powder mortar with reliable quality lies in the mastery of the particle size of the raw materials and the accuracy of the feeding ratio, which is realized in the automatic production line of dry powder mortar.
3. Mineral admixtures
The mineral admixtures of dry powder mortar are mainly: industrial by-products, industrial waste and some natural ores, such as: slag, fly ash, volcanic ash, fine silica powder, etc. The chemical composition of these admixtures is mainly silicon containing calcium oxide. Aluminum hydrochloride has high activity and hydraulic hardness.
4. Admixture
The admixture is the key link of the dry powder mortar, the type and quantity of the admixture and the adaptability between the admixtures are related to the quality and performance of the dry powder mortar. In order to increase the workability and cohesion of the dry powder mortar, improve the crack resistance of the mortar, reduce the permeability, and make the mortar not easy to bleed and separate, so as to improve the construction performance of the dry powder mortar and reduce the production cost. Such as polymer rubber powder, wood fiber, hydroxymethyl cellulose ether, hydroxypropyl methyl cellulose, modified polypropylene fiber, PVA fiber and various water reducing agents.
Post time: Apr-26-2024