The Functions of Common Mortar Additives Such as Rubber Powder
Release Time:
2020-05-15
Source:
1. Redispersible Latex Powder
Redispersible latex powder is a powdered organic binder produced by spray-drying a specially formulated emulsion (a polymeric polymer). Upon contact with water, this powder rapidly redisperses into an emulsion that exhibits the same properties as the original emulsion: after the water evaporates, it forms a film characterized by high flexibility, excellent weather resistance, and strong adhesion to a wide range of substrates.
Redispersible latex powder is an indispensable basic ingredient in dry-mix mortars. It enhances mortar performance by improving strength, increasing bond strength to various substrates, and boosting flexibility and deformability, as well as compressive strength, flexural strength, wear resistance, toughness, adhesion, water retention, and workability. Moreover, the hydrophobic nature of latex powder imparts excellent waterproofing properties to the mortar. Redispersible latex powder is primarily used in dry-mix mortars such as interior and exterior wall putties, tile adhesives, tile grouts, dry-mix interface agents, external thermal insulation mortars for exterior walls, self-leveling mortars, repair mortars, decorative mortars, and waterproof mortars; structurally, these are all high-molecular-weight copolymers—either binary or ternary copolymers.
2. Polycarboxylate Superplasticizer
An efficient water-reducing admixture for construction materials that, when used with mineral binders—such as ordinary Portland cement, calcium chloride cement, and calcium sulfate cement—exerts a combined effect of electrostatic repulsion and steric hindrance. Compared with conventional water reducers, this product exhibits superior anti-flocculation performance and longer-lasting effectiveness. Polycarboxylate-based water reducers, as a new generation of admixtures, offer high water reduction, low dosage requirements, high performance, minimal slump loss, excellent compatibility with cement, low shrinkage, aesthetically pleasing concrete microstructure, and the ability to meet the demands of various specialized structural applications. Meanwhile, the price of polycarboxylate water reducers is steadily declining, increasing the likelihood that batching plants will increasingly adopt these admixtures in low-grade concrete mixes.
3. Defoamer
Defoamers are surfactants specifically formulated for cement- and gypsum-based dry-mix mortars. They exhibit excellent dispersibility, rapid defoaming performance, high stability, broad compatibility, chemical inertness, and require only low dosages. Defoamers effectively eliminate or suppress microbubbles generated during the construction or manufacturing of building materials, resulting in a smooth, even surface finish, a dense internal structure, and enhanced product performance. They also impart outstanding long-term durability and shear stability while increasing compressive strength. Powdered defoamers are increasingly being used in modern building materials. In mortar applications, defoamers inhibit foam formation and destabilize existing foam. The underlying mechanism is as follows: defoamers penetrate the liquid film, reducing its viscosity and creating a new interface with lower surface tension, which diminishes the film’s elasticity, accelerates liquid drainage, and ultimately leads to thinning and rupture of the film. Today’s defoamers used in mortar products are typically formulated as composite systems consisting of a primary active ingredient combined with one or more auxiliary additives.
