The use of mortar as an insulation material in construction can improve the insulation performance of the external wall insulation layer, reduce indoor heat loss, and avoid uneven heating among users, so it has been widely used in building construction. Moreover, the cost of this material is relatively low, which saves the cost of the project, and has high heat insulation and moisture resistance.
A. Raw material selection and function
1. Vitrified microbead lightweight aggregate
The most important ingredient in mortar is vitrified microbeads, which are commonly used thermal insulation materials in modern building construction and have good thermal insulation properties. It is mainly made of an acidic glass material through high-tech processing.
From the surface of the mortar, the particle distribution of the material is extremely irregular, like a cavity with many holes. However, during the construction process, the texture of this material is actually very smooth, and it has a good seal to the wall. The material is very light, has good heat insulation, and has the characteristics of high temperature resistance and wear resistance.
Generally speaking, the thermal conductivity of vitrified microbeads is a prominent feature, especially the thermal conductivity of the surface is the strongest, and the heat resistance is also very high. Therefore, during the use of vitrified microbeads, construction personnel should control the distance and area between each particle in order to realize the thermal insulation and thermal insulation function of the thermal insulation material.
B. Chemical plaster
Chemical gypsum is another important component of mortar. It can also be called industrial recovery gypsum. It is mainly composed of calcium sulfate waste residue, so its production is very convenient, and it can realize the effective use of resources and save energy.
With the development of the economy, many factories discharge some industrial waste and pollutants every day, such as desulfurized gypsum such as phosphogypsum. Once these wastes enter the atmosphere, they will cause air pollution and affect people’s health. Therefore, chemical gypsum can be said to be a renewable energy source, and it also realizes the utilization of waste.
According to various pollution statistics, phosphogypsum is a relatively highly polluting substance. If a factory does not discharge phosphogypsum once, it will cause serious pollution to the surrounding environment. However, this substance can become the main source of chemical gypsum. Element. Through the screening and dehydration of phosphogypsum, researchers completed the process of turning waste into treasure and formed chemical gypsum.
Desulfurization gypsum can also be called flue gas desulfurization gypsum, which is an industrial product formed through desulfurization and purification treatment, and its composition is basically the same as that of natural gypsum. The free water content of desulfurized gypsum is generally relatively high, which is much higher than that of natural gypsum, and its cohesiveness is relatively strong. Many problems are also prone to occur during the entire production process. Therefore, the production process of building gypsum cannot be the same as that of natural gypsum. It is necessary to adopt a special drying process to reduce its moisture content. It is formed by screening it and calcining at a certain temperature. Only in this way can it meet the national certification standards and meet the requirements of thermal insulation construction.
C. Admixture
The preparation of chemical gypsum insulation mortar must use building chemical gypsum as the main material. Vitrified microbeads are often made of lightweight aggregate. Researchers have changed its properties through admixtures to meet the needs of construction projects.
When preparing thermal insulation mortar, construction personnel should pay attention to the characteristics of construction chemical gypsum, such as viscosity and large water volume, and choose admixtures scientifically and rationally.
1. Composite retarder
According to the construction requirements of gypsum products, the working time is an important indicator of its performance, and the main measure to prolong the working time is to add retarder. Commonly used gypsum retarders include alkaline phosphate, citrate, tartrate, etc. Although these retarders have a good retarding effect, they will also affect the later strength of gypsum products. The retarder used in chemical gypsum thermal insulation mortar is a composite retarder, which can effectively reduce the solubility of hemihydrate gypsum, slow down the speed of crystallization germ formation, and slow down the crystallization process. The retarding effect is obvious without loss of strength.
2. Water retention thickener
In order to improve the workability of mortar, improve water retention, fluidity and sag resistance, it is usually necessary to add cellulose ether. The use of methyl hydroxyethyl cellulose ether can better play the role of water retention and thickening, especially in summer construction.
3. Redispersible latex powder
In order to improve the cohesion, flexibility and adhesion of the mortar to the substrate, redispersible latex powder should be used as an admixture. Redispersible latex powder is a powdery thermoplastic resin obtained by spray drying and subsequent processing of high molecular polymer emulsion. The polymer in the mortar mixture is a continuous phase, which can effectively inhibit or delay the generation and development of cracks. Usually, the bonding strength of mortar is achieved by the principle of mechanical occlusion, that is, it is gradually solidified in the gaps of the base material; the bonding of polymers is more dependent on the adsorption and diffusion of macromolecules on the bonding surface, and the methyl The hydroxyethyl cellulose ether works together to infiltrate the surface of the base layer, making the surface of the base material and the surface of the mortar close in performance, thereby improving the adsorption between them and significantly improving the bonding performance.
4. Lignin fiber
Lignocellulosic fibers are natural materials that absorb water but do not dissolve in it. Its function lies in its own flexibility and the three-dimensional network structure formed after mixing with other materials, which can effectively weaken the drying shrinkage of the mortar during the drying process of the mortar, thereby improving the crack resistance of the mortar. In addition, the three-dimensional space structure can lock water 2-6 times its own weight in the middle, which has a certain water retention effect; at the same time, it has good thixotropy, and the structure will change when external forces are applied (such as scraping and stirring). And arranged along the direction of movement, the water is released, the viscosity decreases, the workability is improved, and the construction performance can be improved. Tests have shown that short and medium lengths of lignin fibers are suitable.
5. Filler
The use of heavy calcium carbonate (heavy calcium) can change the workability of the mortar and reduce the cost.
6. Preparation ratio
Construction chemical gypsum: 80% to 86%;
Composite retarder: 0.2% to 5%;
Methyl hydroxyethyl cellulose ether: 0.2% to 0.5%;
Redispersible latex powder: 2% to 6%;
Lignin fiber: 0.3% to 0.5%;
Heavy calcium: 11% to 13.6%;
The mortar mix ratio is rubber: vitrified beads = 2: 1 ~ 1.1.
7. Construction process
1) Clean the base wall.
2) Moisten the wall.
3) Hang the vertical, square, and elastic plaster thickness control lines.
4) Apply interface agent.
5) Make gray cakes and standard tendons.
6) Apply chemical gypsum vitrified bead insulation mortar.
7) Acceptance of the warm layer.
8) Apply gypsum anti-cracking mortar, and press in alkali-resistant glass fiber mesh cloth at the same time.
9) After acceptance, plaster the surface layer with plaster.
10) Grinding and calendering.
11) Acceptance.
8. Conclusion
To sum up, thermal insulation mortar is one of the important thermal insulation materials in construction engineering. It has good heat insulation and thermal insulation properties, which can reduce the input cost of construction engineering and realize energy saving and environmental protection in construction engineering.
With the continuous development of society, in the near future, researchers in our country will definitely develop better and more environmentally friendly insulation materials.
Post time: Mar-24-2023