What is dry mix mortar?

Dry-mixed mortar is mainly divided into two categories: ordinary mortar and special mortar. Ordinary mortars include: masonry mortar, plastering mortar, floor mortar, etc.; special mortars include: tile adhesives, dry powder interface agents, external thermal insulation mortars, self-leveling mortars, waterproof mortars, repair mortars, internal and external wall putties, caulking agents, grouting

 

Dry-mixed mortar is a mortar supplied in a commercial form. The so-called commercial mortar is not mixed on site, but mixed in a centralized manner in the factory. According to the production and supply form, commercial mortar can be divided into premixed (wet) mortar and dry-mixed mortar.

Definition

1. Ready wet-mixed mortar

Ready wet-mixed mortar refers to a mortar mixture made of cement, sand, water, fly ash or other admixtures, and admixtures, which are mixed evenly in a certain proportion in the factory, transported to a designated location by a mixer truck, and used under specified conditions. Commonly known as premixed mortar.

2. Ready dry-mixed mortar Dry-mixed mortar refers to a powdered or granular mixture of fine aggregates and inorganic binders, mineral admixtures, and other admixtures produced by a professional manufacturer, dried and screened, mixed in a certain proportion, and then added with water and mixed according to the instructions at the construction site to form a mortar mixture. The product can be packaged in bulk or bagged. Dry-mixed mortar is also called dry-mixed mortar, dry powder, etc.
3. Ordinary dry-mixed masonry mortar refers to premixed dry-mixed mortar used for masonry projects;
4. Ordinary dry-mixed plastering mortar refers to premixed dry-mixed mortar used for plastering projects;
5. Ordinary dry-mixed floor mortar refers to premixed dry-mixed mortar used for building floors and roofs (including the surface layer and leveling layer of the roof).

6. Special dry-mixed mortar (Special ready dry-mixed mortar) refers to special building and decorative dry-mixed mortar with special performance requirements, external insulation plastering mortar, self-leveling floor dry-mixed mortar, interface agent, finishing mortar, waterproof mortar, etc. Compared with traditional preparation processes, dry-mixed mortar has many advantages such as stable quality, complete varieties, high production efficiency, excellent quality, good construction performance, and easy use.

Classification of dry-mixed mortar

Dry-mixed mortar is mainly divided into two categories: ordinary mortar and special mortar. Ordinary mortars include: masonry mortar, plastering mortar, floor mortar, etc.; special mortars include: tile adhesives, dry powder interface agents, external thermal insulation mortars, self-leveling mortars, waterproof mortars, repair mortars, internal and external wall putties, caulking agents, grouting materials, etc.

1. Masonry mortar

Masonry mortar refers to mortar used for masonry of block-shaped building materials such as bricks, stones, and blocks.

2. Plastering mortar

The mortar of plastering mortar is required to have good workability and be easy to spread into a uniform and smooth thin layer for easy construction; it must also have a high bonding strength, and the mortar layer must be able to bond firmly to the bottom surface and not crack or fall off after long-term use. Plastering mortar can protect buildings and walls. It can resist the erosion of buildings by natural environments such as wind, rain, and snow, improve the durability of buildings, and achieve a smooth, smooth and beautiful effect.

3 Tile Adhesive

Tile adhesive, also known as tile glue, can be used to bond ceramic tiles, polished tiles and natural stones such as granite. Specially designed bonding mortars can bond inorganic rigid decorative blocks according to different substrates (such as wood boards, cement fiber boards), facing materials and various extreme climatic conditions (such as humidity and temperature differences).

4 Interface mortar

Interface mortar, also known as interface treatment agent, can not only firmly bond the base layer, but also its surface can be firmly bonded by the new adhesive. It is a material with two-way affinity. Due to the different surface characteristics of the substrate, such as porous highly absorbent materials, smoother low-absorbent materials, non-porous non-absorbent materials, and the cohesive force generated by the shrinkage and expansion of the subsequent covering materials of the substrate, resulting in bonding failure, etc., it is necessary to use an interface treatment agent to enhance the bonding force between the two materials.

5 External thermal insulation mortar

External thermal insulation mortar: It uses lightweight aggregates with high toughness and excellent crack resistance (such as polystyrene foam particles or expanded perlite, vitrified microspheres, etc.), combined with high-quality dry-mixed mortar additives such as fiber, cellulose ether, latex powder, etc., so that the mortar has thermal insulation performance, good construction performance, crack resistance and weather resistance, and is easy to construct, economical and practical. At the same time, it meets the needs of energy-saving buildings and has the characteristics of light weight, heat insulation and heat preservation. (Common ones include polymer bonding mortar, polymer plastering mortar, etc.)

6 Self-leveling mortar

Self-leveling mortar: It provides a suitable flat, smooth and solid paving base on an uneven base (such as the surface to be renovated, mortar layer, etc.) to set up various floor materials. For example, fine leveling materials for carpets, wooden floors, PVC, tiles, etc. Even for large areas, efficient construction can be carried out.

7 Waterproofing mortar is a cement-based waterproof material. It is a waterproof material with cement and filler as the main components. It achieves waterproof function requirements by adding polymers, additives, admixtures or special cement to mix dry mortar. This type of material is called JS composite waterproof coating in the market.

 

8 Repair mortar

Some repair mortars are only for aesthetic reasons, to carry out decorative repairs on concrete that does not contain steel bars and has no load-bearing function. Some are to maintain and re-establish structural stability and function, to repair damaged load-bearing reinforced concrete structures. It is part of the concrete repair system and is used for repairing and restoring roads, bridges, parking lots, tunnels, etc.

9 Interior and exterior wall putty Putty is a thin layer of leveling mortar, which is divided into single-component and two-component. It is an auxiliary material for architectural decorative coatings and is used in conjunction with latex coatings.

10 Sealing agent is also called grouting agent, which is used to fill the joints between tiles or natural stones, provide beautiful surfaces and bonding and waterproofing between facing tiles. Protect the tile base material from mechanical damage and the negative effects of water penetration.

11 Grouting material is a cement-based grouting material with shrinkage compensation function. It has micro-expansion and produces micro-expansion in both the plastic stage and the hardening period to compensate for shrinkage. It is often used for shrinkage compensation, early strength, high-strength grouting, repair, and forming a high-strength, dense, and impermeable hardened body. It can obtain good fluidity at a low water-cement ratio, which is conducive to construction pouring and maintenance and coating construction.

Analysis of dry-mixed mortar problems

At present, dry-mixed mortar is in a rapid development stage. The use of dry-mixed mortar can effectively reduce resource loss, improve project quality, and improve the urban environment. However, dry-mixed mortar still has many quality problems. If it is not standardized, its advantages will be greatly reduced and even counterproductive. Only by strengthening quality control in all aspects such as raw materials, finished products, and construction sites can the advantages and functions of dry-mixed mortar be truly brought into play. Analysis of common causes

01 Cracks

There are four most common types of cracks: uneven settlement cracks in the base layer, temperature cracks, drying shrinkage cracks, and plastic shrinkage cracks. Uneven settlement of the base layer Uneven settlement of the base layer mainly refers to cracks caused by the sinking of the wall itself. Temperature cracks Temperature changes can cause thermal expansion and contraction of materials. When the temperature stress caused by temperature deformation under constraint conditions is large enough, temperature cracks will occur in the wall. Drying shrinkage cracks Drying shrinkage cracks are referred to as shrinkage cracks. As the water content of masonry such as aerated concrete blocks and fly ash blocks decreases, the materials will experience greater shrinkage deformation. The shrunken materials will still expand when wet, and the materials will shrink again after dehydration. Plastic shrinkage The main reason for plastic shrinkage is that in a short period of time after the mortar is plastered, the water content is reduced when it is in a plastic state, resulting in shrinkage stress. Once the shrinkage stress exceeds the bonding strength of the mortar itself, cracks will occur on the surface of the structure. The plastic shrinkage of the plastering mortar surface is affected by time, temperature, relative humidity and the water retention rate of the plastering mortar itself. In addition, design negligence, failure to set grid strips according to the requirements of the specifications, no targeted crack prevention measures, unqualified material quality, poor construction quality, violation of design and construction regulations, masonry strength that does not meet the design requirements, and lack of experience are also important causes of wall cracks.

 

2 Hollowing

There are four main reasons for hollowing: untreated surface of base wall, rush to plaster before wall curing time is insufficient, too thick single-layer plastering, improper use of plastering materials. Untreated surface of base wall, dust on the wall surface, residual mortar and isolation agent during pouring are not cleaned up, smooth concrete surface is not coated with interface agent or sprayed and roughened, and water is not sprayed in advance before plastering to fully moisten, etc., which will cause hollowing. Rushing to plaster after insufficient wall curing time. Plastering starts before the wall is fully deformed, and the shrinkage of the base and plastering layers is inconsistent, resulting in hollowing. Too thick single-layer plastering When the wall is not flat or has defects, it is not treated in advance, and the plastering is eager to succeed and survive at one time. The plastering layer is too thick, causing its shrinkage stress to be greater than the mortar bonding force, resulting in hollowing. Improper use of plastering materials The strength of the plastering mortar does not match the strength of the base wall, and the shrinkage rate is too different, which is another reason for hollowing.

 

3 Surface sanding

Surface sanding is mainly due to the small proportion of cementitious materials used in the mortar, too low sand fineness modulus, excessive mud content, insufficient mortar strength leading to sanding, too low mortar water retention rate and too fast water loss, inadequate or no maintenance after construction leading to sanding. 04 Powdering and peeling Powdering and peeling are mainly due to the low water retention rate of the mortar, poor stability of the components in the mortar, too large proportion of admixtures used, and some powder floating up due to rubbing, smearing and polishing, gathering on the surface, resulting in low surface strength and powdering and peeling.