Two or more additives, sometimes as many as a dozen, are mixed into one component to become a special additive for a particular type of dry-mixed mortar to simplify the mortar process formula and reduce user inventory. This component product is usually called a composite dry mortar product additive.
Composite dry-mixed mortar additives are not simply compounded but are formulated based on screening and comparing original formulas, many tests, and repeated testing. When formulating such additives, various types of components should also be considered. Additives are carefully tested and accepted, and the proportions must be constantly changed during mass production to meet the standardized factory specifications. A composite dry-mixed mortar additive model is often only suitable for one or two to three types of dry mortar.
Composite dry-mixed mortar additives guide production technology and reduce production costs. The technical performance of this type of additive requires cutting-edge technology, and the promotion and application require simplicity.
Fiber
Cement is a cementitious material and has good construction performance. Hardened cement mortar has high compressive strength. However, as a base material, it also has inherent severe defects. The tensile strength is far lower than its compressive strength. It is a typical brittle material, cast iron material, with poor crack resistance; there are a large number of dry shrinkage cracks and temperature cracks in the components; these cracks will continue to change and develop over time; small cracks will eventually develop into large cracks. Due to these reasons, the cracking of cement products and components and the expansion of these cracks can reduce the structure’s impermeability, reduce the product’s strength and stiffness, and ultimately lead to the deterioration of the structural matrix and shorten the service life.
The most direct and effective way to overcome the defects of cement and its products is to incorporate fibers into the cement base material. In addition to the various functions it should have, qualified commercial mortar must also have functions such as crack resistance, seepage resistance, burst resistance, freeze-thaw resistance, impact resistance, wear resistance, aging resistance, and ultraviolet resistance. The new fibers added to cement mortar can be natural inorganic or manufactured inorganic fibers or composite fibers and metal fibers mixed with various fibers.
Adding fiber to cement mortar can prevent the expansion of original defective cracks in the mortar matrix and effectively prevent and delay the emergence of new cracks; improve the compactness of the mortar matrix, prevent the intrusion of external moisture, and improve water resistance and impermeability; improve the frost resistance and fatigue resistance of the mortar matrix and improve its durability; enhance the rigidity of the mortar matrix, increase toughness, reduce brittleness, and increase the deformation force and impact resistance of the mortar matrix; improve the surface properties of cement mortar to make its surface more dense, delicate, smooth, beautiful, and resistant to aging; the use of high-strength and high-modulus fibers can improve the tensile strength of the mortar matrix.
Mortar mixed with fibers has many advantages over ordinary plain mortar. Specifically, it enhances crack resistance and improves the ability to resist cracks. It also enhances the toughness of the material. Even after micro-cracks occur, the fibers can resist the pull of external forces; high-strength and high-modulus fibers can enhance the tensile strength, flexural strength, and shear strength of the mortar matrix, strengthen the resistance to freeze-thaw effects and improve the fatigue resistance of the mortar. The above advantages have promoted the gradual expansion of the fiber-reinforced cement mortar application fields, which can be used in all fields of dry mortar.
The principle of fiber crack resistance is that if high-strength and high-modulus fibers are uniformly and disorderly dispersed in the cement mortar matrix when the cement mortar matrix is subject to external forces or internal stress changes, the fibers will play a specific role in limiting and limiting the expansion of hindering effect.
