Dry mix mortar is mortar supplied in commercial form. The so-called commercialized mortar does not carry out batching on site, but concentrates batching in the factory. According to the production and supply form, commercial mortar can be divided into ready-mixed (wet) mortar and dry-mixed mortar.
Definition
1. Ready wet-mixed mortar
Ready-mixed wet mortar refers to cement, sand, water, fly ash or other admixtures, and admixtures, etc., which are mixed in a certain proportion in the factory, and then transported to the designated place by the mixer truck. The finished mortar mixture under the condition. Commonly known as ready-mixed mortar.
2. Ready dry-mixed mortar
Dry-mixed mortar refers to a powdery or granular mixture that is produced by a professional manufacturer and mixed with fine aggregates, inorganic cementitious materials, mineral admixtures, cellulose ethers,and other admixtures after drying and screening in a certain proportion. Add water and stir according to the instructions on site to form a mortar mixture. The packaging form of the product can be in bulk or in bags. Dry-mixed mortar is also called dry-mixed mortar, dry powder material, etc.
3. Ordinary dry-mix masonry mortar
Refers to the ready-mixed dry-mixed mortar used in masonry projects;
4. Ordinary dry-mix plastering mortar
Refers to the ready-mixed dry-mixed mortar used for plastering works;
5. Ordinary dry-mixed floor mortar
It refers to the ready-mixed dry-mixed mortar used for building ground and roof (including roof surface and leveling layer).
6. Special ready dry-mixed mortar
Refers to special construction and decorative dry-mixed mortar with special requirements on performance, external thermal insulation plastering mortar, self-leveling ground dry-mixed mortar, interface agent, facing mortar, waterproof mortar, etc.
Compared with the traditional preparation process, dry-mixed mortar has many advantages such as stable quality, complete variety, high production efficiency, excellent quality, good construction performance, and convenient use.
Dry-mixed mortar classification
Dry-mixed mortar is mainly divided into two categories: ordinary mortar and special mortar.
The ordinary mortar includes: masonry mortar, plastering mortar, ground mortar, etc.;
Special mortars include: tile adhesives, dry powder interface agents, external thermal insulation mortars, self-leveling mortars, waterproof mortars, repair mortars, interior and exterior wall putty, caulking agents, grouting materials, etc.
1 masonry mortar
Masonry mortar Mortar used for masonry bricks, stones, blocks and other block building materials.
2 plastering mortar
The mortar for plastering mortar is required to have good workability, and it is easy to plaster into a uniform and flat layer, which is convenient for construction; it must also have high cohesive force, and the mortar layer should be firmly bonded to the bottom surface without cracking or cracking after long-term use. Falling off, 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 smooth, clean and beautiful effects.
3 tile adhesive
Tile adhesive, also known as tile glue, can be used to bond ceramic tiles, polished tiles and natural stone such as granite. The specially designed bonding mortar can And various extreme climatic conditions (such as humidity, temperature difference) to bond inorganic rigid decorative blocks.
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, and it is a material with two-way affinity. Due to the different surface properties of the substrate, such as porous strong water-absorbent material, smooth low-water-absorbent material, non-porous non-water-absorbent material, and cohesion caused by the shrinkage and expansion of the subsequent cladding material of the substrate, resulting in bond failure, etc., Both require the use of interface treatment agents to enhance the bonding force between the two materials.
5 External insulation mortar
External thermal insulation mortar: it is made of lightweight aggregates with high toughness and excellent crack resistance (such as polystyrene foam particles or expanded perlite, vitrified microbeads, etc.), combined with high-quality dry mortar such as fibers, cellulose ether, and latex powder. Additives for mixed mortar, so that the mortar has thermal insulation performance, good constructability, crack resistance and weather resistance, and it is convenient for construction, economical and practical. polymer mortar. (Common polymer bonding mortar, polymer plastering mortar, etc.)
6 self-leveling mortar
Self-leveling mortar: it is on an uneven base (such as the surface to be renovated, mortar layer, etc.), providing a suitable flat, smooth and firm bedding base for erecting various floor materials. Such as fine leveling materials for carpets, wooden floors, PVC, ceramic tiles, etc. Even for large areas, it can also be constructed efficiently.
7 waterproof mortar
It belongs to the cement-based waterproof material. The waterproof material mainly consists of cement and fillers. It can meet the waterproof function requirements by adding polymers, additives, admixtures or dry-mixed mortar mixed with special cement. This kind of material has become JS composite waterproof coating in the market.
8 repair mortar
Some repair mortars are used for decorative repair of concrete that does not contain steel bars and have no load-bearing function for aesthetic reasons, and some are used to repair damaged load-bearing reinforced concrete structures in order to maintain and re-establish structural stability and functions. Part of the concrete repair system, it is applied to the repair and restoration of road bridges, parking lots, tunnels, etc.
9 Putty for interior and exterior walls
Putty is a thin layer of leveling mortar, which is divided into one-component and two-component. Auxiliary material for architectural decoration paint, used together with latex paint.
10 caulk
Also called grouting agent, it is used to fill the joint material between tiles or natural stone, provide an aesthetic surface and bond between facing tiles, seepage prevention, etc. Protects the tile base material against mechanical damage and the negative effects of water penetration.
11 grouting material
Cement-based grouting material with the function of compensating shrinkage, with micro-expansion, micro-expansion occurs in the plastic stage and hardening stage to compensate for shrinkage. hardened body. Good fluidity can be obtained under low water-cement ratio, which is beneficial to construction pouring and maintenance smearing construction.
Analysis of dry-mixed mortar problems
At present, dry-mixed mortar is in a stage of rapid development. The use of dry-mixed mortar can effectively reduce resource consumption, improve project quality, and improve the urban environment. However, there are still many quality problems in dry-mixed mortar. If it is not standardized, its advantages will be greatly reduced, or even counterproductive. Only by strengthening quality control in various aspects such as raw materials, finished products, and construction sites, can the advantages and functions of dry-mixed mortar be truly brought into play.
Common cause analysis
1 crack
There are four types of the most common cracks: base uneven settlement cracks, temperature cracks, drying shrinkage cracks, and plastic shrinkage cracks.
Uneven settlement of base
The uneven settlement of the base mainly refers to the cracking caused by the subsidence of the wall itself.
temperature crack
The temperature change will cause thermal expansion and contraction of the material. When the temperature stress caused by the temperature deformation under the constraint conditions is large enough, the wall will generate temperature cracks.
drying shrinkage cracks
Drying shrinkage cracks are referred to as drying shrinkage cracks for short. As the water content of masonry such as aerated concrete blocks and fly ash blocks decreases, the materials will produce large drying shrinkage deformation. The shrinkage material will still expand after being wet, and the material will shrink and deform again after dehydration.
plastic shrinkage
The main reason for plastic shrinkage is that within a short period of time after the mortar is plastered, shrinkage stress is generated when the moisture is reduced when it is in a plastic state. Once the shrinkage stress exceeds the adhesive strength of the mortar itself, cracks will occur on the surface of the structure. The plastic drying 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, negligence in design, failure to set up grid strips according to specification requirements, non-targeted anti-cracking measures, unqualified material quality, poor construction quality, violation of design and construction regulations, masonry strength not meeting design requirements, and lack of experience are also An important cause of cracks in the wall.
2 hollow
There are four main reasons for the hollowing: the surface of the base wall is not treated, the wall is too long to be plastered due to insufficient maintenance time, the single layer of plaster is too thick, and the plastering material is improperly used.
The base wall surface is not treated
The dust stuck on the wall surface, the residual mortar and the release agent during pouring have not been cleaned, the smooth concrete surface has not been painted with interface agent or sprayed and brushed, and the water has not been fully wetted before plastering, etc., will cause hollowing Phenomenon.
If the wall maintenance time is not enough, it is eager to plaster. Plastering begins before the wall is fully deformed, and the shrinkage of the base layer and the plastering layer is inconsistent, resulting in hollowing.
Single layer plaster too thick
When the flatness of the wall is not good or there is a defect, there is no advance treatment, and the plastering is eager for success, and it survives at one time. The plastering layer is too thick, causing its shrinkage stress to be greater than the bonding force of the mortar, 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 difference in shrinkage is too large, which is another reason for the hollowing.
3 Sand off the surface
The sand loss on the surface is mainly due to the small proportion of cementitious materials used in the mortar, the sand fineness modulus is too low, the mud content exceeds the standard, the mortar strength is insufficient to cause sanding, the water retention rate of the mortar is too low and the water loss is too fast, and the maintenance after construction is not in place. Or there is no maintenance to cause sand loss.
4 powder peeling
The main reason is that the water retention rate of the mortar is not high, the stability of each component in the mortar is not good, and the proportion of the admixture used is too large. Due to rubbing and calendering, some powders float up and gather on the surface, so that the surface strength is low and Powdery skin.