2022.06.20
(1) Production process
Waste Styrofoam or leftovers from the production of Styrofoam. Crushed into 5-15mm particles by a crusher. The air is sent to the high-level silo for storage. It is put into the mixer by metering during production. as a lightweight aggregate. Add No. 525 cement, water, foaming agent, foam stabilizer, etc., and mix to form a light weight and good cohesive mixing material. Then injection molding. After curing, it becomes cement polystyrene insulation board.
(2) The main factors affecting the performance of the insulation board
The test shows the bulk density of the cement polystyrene insulation board. There is a close relationship between strength and thermal conductivity. and restrict each other. The bulk density of the board is increased. Strength increases. But the thermal conductivity rises. Insulation performance decreased; on the contrary. If the weight is reduced.
Although it can improve the thermal insulation performance. And the strength will decrease. Table 4 and Table 5 show the relationship between the bulk density, strength and thermal conductivity of the cement polystyrene insulation board.
The compressive strength of plates under different bulk density
Bulk density (kg/m2) 288 305 314 332 353 369
Strength 7d(MPa) 0.21 0.28 0.30 0.33 0.42 0.63
Thermal conductivity of cement polystyrene insulation board with different bulk density
Bulk density (kg/m2) 240 300 350 400
Strength 7d(MPa) 0.040 0.090 0.099 0.116
in the actual production process. Changes in the amount of each ingredient in the mix. The change of raw material quality has a significant impact on the above-mentioned basic properties of cement polystyrene insulation board.
(1) Influence of cement dosage
In unit volume. The increase of cement dosage will directly lead to the corresponding increase in bulk density and strength. The thermal conductivity increases accordingly. Insulation performance decreased. on the contrary. The bulk density and thermal conductivity decrease accordingly. Good thermal insulation performance. strength decreased.
(2) Influence of water-cement ratio
Same as other cement products. The water added to the cement polystyrene insulation board mixture has the dual functions of cement hydration and mixing workability. How much water is used. That is, the level of water-cement ratio significantly affects the workability of the mixed material and the strength of the product. When the water-cement ratio is large, the fluidity of the mixture is good. Easy to shape. But the strength is reduced, and even affects the stability of the bubbles, resulting in bleeding and segregation; the water-cement ratio is small. High strength. However, if the water-cement ratio is too small, the workability of the mixture will be deteriorated, forming is difficult, and the introduced air bubbles cannot be uniformly dispersed.
(3) Influence of gas content
The feature of cement polystyrene insulation board is to introduce fine air bubbles into the cement of the cementitious material. Make it foamed grout. The amount of bubbles introduced has a great influence on the properties of the mixture and the strength, bulk density, and thermal conductivity of the plate. The test results in Table 6 and Figure 4 illustrate this effect.
(4) Influence of shape and content of polystyrene foam particles
The shape and content of the foam particles have a great influence on the properties of the mixture and products. The test results in Table 7 clearly illustrate this difference.
Increasing the content of polystyrene foam particles, its effect is related to the effect of cement content. Because the increased polystyrene foam particles replace the same volume of cement. Therefore, the bulk density and strength of the sheet are reduced. The thermal insulation performance is improved.
(5) Influence of temperature
Ambient temperature during the production process and sheet maintenance. A more suitable temperature is between 5 and 40 °C. Low temperature. Cement hydration rate slowed down. The specified strength cannot be achieved within the specified curing period. High temperature. Lead to rapid loss of water in mixtures and products. Cement cannot be hydrated normally, and the strength of the product is low. In addition, beyond this range, the stability of the mixture is easily deteriorated, which ultimately affects the mechanical and thermal properties of the product.
(3) Structural characteristics of cement polystyrene insulation board
Usually when the cement slurry is mixed with polystyrene foam particles. The internal structure of the obtained composite material will have two structural types, namely open structure and closed structure, due to the amount of cement.
When the amount of cement is small, it is an open structure. At this time, the cement slurry can only wrap the polystyrene foam particles. It is not enough to fill the voids between the particles and the foam particles are packed in the densest way. The space occupied is 52.4-73.8% of the total volume, and the rest is the voids between the particles that are not filled with cement slurry. When the amount of cement is large, it is a closed structure. At this time, the cement slurry not only wraps the foam particles. And all the voids between the particles are filled. And there is a certain distance between the particles (as shown in Figure 5o). Cement polystyrene insulation board is in the case of less cement consumption. A certain amount of air bubbles are introduced into the cement paste by adding additives such as foaming agents. These tiny bubbles with a diameter of 0.3 to 0.8 mm are uniformly dispersed in the cement slurry. Form a stable foam cement slurry. The foamed cement slurry completely wraps the foam particles and fills the gaps between the particles, forming the internal structure of the cement polystyrene insulation board.
Structural type of cement polystyrene insulation board The structural characteristics of cement polystyrene insulation board:
(1) Improve the cohesion and dispersibility of the mixture. It will not cause the cement slurry to sink. The phenomenon of layered segregation of floating polystyrene particles. At the same time, these small bubbles reduce the friction of light aggregates. Increase the workability of the mixture. Easy to cast and form.
(2) The foamed cement slurry wraps around the polystyrene particles. Make the cement dosage play a greater role in cementation under the condition of less. The formation of the insulation board is uniform and dense. Light weight. There is a certain strength. Good thermal insulation performance.
(3) There are tiny air bubbles inside the material. It can improve the frost resistance of the product; the polystyrene particles accounting for about 70% of the volume in the product hardly absorb water, and the water absorption rate of the cement polystyrene insulation board is lower than that of the air-entrained concrete. And the water absorption speed is slow.
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