Study on Process and Properties of Foam-Polystyrene Insulation Mortar

At present, the most widely used building energy-saving materials are polystyrene board, expanded perlite thermal insulation mortar and EPS thermal insulation mortar. As a plate-shaped insulation material, the polystyrene board is pasted and nailed on the outer surface of the outer wall, covered with a glass fiber mesh cloth, and then covered with cement. The plate has light weight, thin thickness and good thermal insulation effect 111, but in the actual use process, there are surface cracks, adhesive layer hollowing, falling off, indoor easy frosting, condensation and other issues 121. Therefore, people began to turn to insulation Research on slurry insulation materials with good performance and convenient construction. Among them, EPS thermal insulation mortar has gained wide attention in the industry due to its good thermal insulation, stability and crack resistance. The thermal conductivity of polystyrene particles <0041W/(mK) is an ideal thermal insulation aggregate, but the gradation is not good due to the small particle size range of the polystyrene particles (2mm~5mm). Therefore, if a single polystyrene pellet is used as the insulating aggregate, large pores are present between the particles. These pores require more gelling material to fill, which tends to increase the apparent density of the insulating mortar and reduce the thermal insulation performance. At the same time, compared with expanded perlite and ceramsite thermal insulation mortar, EPS insulation mortar still has the problem of high cost and high cost, which affects the promotion and application.

The foam cement used as the heat preservation and oil well filling material is a microporous material which is obtained by stirring, casting and curing foam and cement paste. The thermal insulation unit is a microporous layer left after the foam disappears, but these micropores do not have the bearing capacity, and the excess bubbles are difficult to be closed and uniformly existed, so the microporosity must be controlled. At present, foam cement with compressive strength of 0 4~06 MPa has an apparent density of generally 400-500 kg/m3, and its thermal conductivity is above 009 WWm IO.

In order to solve the above problems, this study combines two types of materials and further improves the workability of EPS thermal insulation mortar by introducing a large number of closed and uniformly distributed microbubbles (bubble diameter less than 1 mm) in the EPS thermal insulation mortar to replace some EPS particles. In order to achieve the effect of optimized grading, the macroporosity between EPS particles is reduced, the pore structure is improved, and the thermal conductivity and production cost of the material are reduced. In addition, the introduction of fly ash in the foam-EPS thermal insulation mortar, that is, without increasing the bulk density of the foam-EPS thermal insulation mortar, the volume of the slurry is increased and filled into the pores of the foam-EPS thermal insulation mortar, thereby reducing the large Porosity, improve the compressive and flexural strength of insulation materials; can further reduce costs have certain economic and social benefits.

2 Raw materials and their properties 21 Raw materials and basic mix ratio No. 5 ordinary Portland cement, EPS (original foamed granules, particle size less than 5mm, bulk density of 1515kg/m3), foaming agent (CCW-2004 type, rosin) Alkaline type, S-2 type, sodium dodecyl sulfonate), hydroxypropyl methyl cellulose ether (viscosity 10000Pa.s) modifier (polyacrylic acid emulsion, solid content 50% viscosity is 15 ~40Pa.3), 11 grade high quality fly ash.

The basic mix ratio is the basic mix ratio when researching the foam-EPS insulation mortar mixing system: cement dosage 200kg/m3, polyacrylic acid emulsion 8% cellulose ether plus 0 22 test method using self-made foaming machine with speed of 680i/min The high-speed blade agitated foaming agent solvent was prepared for 2 min to produce a similar "tick foam". The bulk density is tested according to GB54863-85; the compressive and flexural strengths are tested according to GB/T17671-1999 cement mortar strength test method (SO method). The thermal conductivity is tested with reference to BG10295. The sample size is 200mmX200mmX40mm. The curing methods and conditions are the same as the compressive strength samples.

3 Test Results and Discussion 31 One of the keys to the preferred production of foaming agent-foam insulation mortar is the choice of blowing agent. There are many substances that can produce foam, but not all materials that produce foam can be used in the production of foam-EPS insulation mortar. Only when the foam and the slurry are mixed, the film is not damaged, and the foaming agent which has sufficient stability and does not have a detrimental effect on the coagulation and hardening of the cementitious material can be used for the production of the thermal insulation mortar. Obtaining a stable, fine and evenly distributed foam is one of the key technologies for the production of foam-EPS insulation mortar. Therefore, it is necessary to analyze and select the foaming agent. 1341. The quality of the foaming agent to form foam is toughness and expansion ratio. And the amount of bleeding and other indicators to measure. The toughness of the foam is the characteristic that the foam does not break in the air for a specified period of time, and is often determined by the sinking distance of the foam column per unit time. The expansion ratio is a multiple of the foam volume greater than the volume of the blowing agent solution. For ease of comparison, the foaming ability is indicated herein by the foaming height. Inject 250ml of foaming agent into a 250ml measuring cylinder, and inject 100ml of foaming agent into the pipette so that the surface level of the measuring cylinder is 450mm away from the pipette opening, let the foaming agent drip vertically into the measuring cylinder, and impact the test solution in the measuring cylinder. After the bubble is generated. Starting from the moment of dropping, the height of the foam in the cylinder after 30s, 3min, and 5min is measured, which is the foaming height. The amount of bleeding refers to the volume of the aqueous foaming agent produced after the foam is destroyed. Table 1 compares the performance of several common blowing agents.

Table 1 Comparison of properties of four foaming agents Item foaming height / foaming trapping amount / mm water volume / m 1 case rosin lye foaming agent bubble large sodium dodecyl sulfonate bubble is small, there are large bubbles exist S -2 type foaming agent bubble small bubble small and uniform, full of elastic process research rosin lye and S-2 type as a foaming agent, the foam-EPS insulation mortar prepared has a large gas content, but the distribution is uneven, the pores are large The strength of the test block is low, and the S-2 type foaming agent has a strong retarding effect, which is unfavorable for the production and use of the foam-EPS thermal insulation mortar. Sodium dodecyl sulfonate is used as a foaming agent, and when the amount of bubbles is large, the test piece collapses easily. The thermal insulation mortar prepared by CCW-2004 foaming agent has a small pore diameter and a uniform distribution. In the subsequent experiments, it was selected as a foaming agent.

32 foam-EPS insulation mortar mixing system research On the one hand, foam, EPS, cement, fiber, water addition order is different, the impact on foam concrete is great; on the other hand, foam has a "life" length, foam is a kind Thermodynamically unstable systems, by their very nature, cannot be stable. The foam is insufficiently stirred with other materials, and the bubbles are difficult to be evenly distributed in the mortar; if the stirring time is too long, the foam structure is destroyed, and the bulk density of the foam-EPS thermal insulation mortar is increased, and the quality is lowered. Therefore, it is necessary to study the stirring process of foam-EPS insulation mortar.

Determination of 321 feeding sequence The feeding sequence of the test design is as follows, the fixed stirring time is 90s. Process 1: After the cement slurry and foam are stirred together, the other raw materials are added together and stirred for a period of time, and cast.

Process 2: The EPS is stirred with a polystyrene emulsion, and after surface modification, other raw materials are mixed and cast. Process 3: All materials of cement, foam, EPS, cellulose ether and polyacrylic emulsion are stirred and mixed together and cast. The test results are shown in Table 2. As seen from Table 2, the stirring time is the same, the density of the test block is smaller, the gas content is higher, the bubble distribution is uniform, and the pores are smaller. When using Process 2 and Process 3, the test block has a high density and a small gas content. This is because the process 1 mixes the foam with the cement and water for a period of time, and then stirs with other materials, not only can the cement slurry pre-wrap the unstable bubbles, avoid the massive destruction of the bubbles, and can be in the cement slurry. A more even distribution. Therefore, the order of addition of Process 1 was employed in the following experiments.

Table 2 Effect of feeding sequence on the performance of bubble-EPS insulation mortar Feeding sequence Dry density Compressive strength / MPa flexural strength / MPa Process 1 Process 2 Process 3 322 Determination of mixing time In order to determine the appropriate mixing time, the following experiment was designed. After the cement and the foam are stirred together (60 for Scheme 1, 30 seconds for Scheme 2, and 60 seconds for Scheme 3), the other raw materials are added and stirred together (solution 1 is 30 s, scheme 2 is 60 s, and scheme 3 is 90 s). The test results are shown in Table 3. Process study Table 3 Effect of stirring time on the performance of bubble-EPS insulation mortar Feeding sequence Dry density Compressive strength / MPa Flexural strength Scheme 1 Scheme 2 Scheme 3 It is seen from Table 3 that the dry density is equivalent Under the conditions, the compressive and flexural strength of the scheme 1 is the highest. This may be because the cellulose ether and polyacrylic acid emulsion in the raw material, as a surfactant, will introduce harmful bubbles of more than 1 mm during the stirring process, which affects the mechanical properties of the foam-EPS thermal insulation mortar. Therefore, the test piece prepared in the scheme 3 is loose in structure and has atmospheric pores. Compared with Scheme 1, Scheme 2 has lower strength, on the one hand, because of the above reasons, and on the other hand, because the foam and cement slurry have insufficient mixing time, the bubbles are not completely evenly distributed in the slurry. Therefore, the stirring time determined in Scheme 1 was used in the following tests.

33 foam-EPS insulation mortar insulation component content determination In the foam-EPS insulation mortar, EPS is in a stacked state, because the EPS particle size is 2mm ~ 5mm, it is a discontinuous distribution, and there are considerable pores inside the accumulation body. In order to reduce the thermal conductivity of the thermal insulation mortar as much as possible, this part is filled with bubbles having a smaller pore size to form a continuously distributed ultra-lightweight material. But there is an optimal ratio of the two. The test results are shown in Table 4. Table 4 The effect of EPS and bubble content on the performance of bubble-EPS insulation mortar. Bubble EPS water-cement ratio compressive strength The flexural strength is partially broken due to the mixing of bubbles in the cement, so the test The bubble content is multiplied by the margin factor. 1.1. It is seen from Table 4 that as the bubble content increases, the water-cement ratio increases within a certain range, but the strength of the foam-EPS insulation mortar does not decrease, but has an increasing trend. . This is because the preparation of the mortar differs from ordinary mortar in that it has a foam introduction process. In order to better introduce the foam into the cement slurry in this process and distribute it evenly and uniformly in the thermal insulation mortar system, the cement slurry is required to have good fluidity. A higher forming water-cement ratio is just a requirement for ensuring good fluidity of the cement mortar. On the other hand, as the appropriate amount of bubbles can be filled in the gap between the EPS particles, the density of the EPS mortar is increased under the condition that the amount of the cement is constant, so that the compressive and flexural strengths are improved. However, when the amount of bubbles exceeds 0.44m3/m3, the compressive and flexural strength of the foam-EPS insulation mortar decreases rapidly. When the bubble content reaches 066m3/m3, the foam-EPS insulation mortar even collapses. This is due to the fact that the bubbles do not have strength. Therefore, the optimum amount of bubbles per m3 foam-EPS thermal insulation slurry is 033m3, that is, the volume ratio of EPS to EPS particles is 3:34. The effect of the amount of fly ash on the performance of foam-EPS thermal insulation mortar is to maintain the foam-EPS insulation. Under the condition that the dry bulk density of the mortar is constant, the amount and density of the slurry are increased, and some cement is replaced by the addition of fly ash. The amount of fixing cementing material is 200kg/m3, the polyacrylic acid emulsion is 6% cellulose ether is 03%, the EPS particle is 11. The foaming amount is 03m3/m3. The test results are shown in Table 5. Table 5EPS and bubble content to bubble-EPS Effect of thermal insulation mortar properties Fly ash/cement/water ash ratio Compressive strength/MPa flexural strength/MPa As seen from Table 5, as the amount of cement replaced by the same amount of fly ash, the resistance of foam-EPS thermal insulation mortar The compressive and flexural strengths first increase. When the blending amount is 10%, the compressive strength is the highest; after the fly ash substitution exceeds 10%, the compressive and flexural strengths begin to decrease. This is because when the amount of substitution of fly ash is not large, the micro-aggregate effect acts. Since the density of fly ash is smaller than that of cement slurry, the volume of the slurry is increased without increasing the bulk density of the foam-EPS insulation mortar, and some of the fly ash particles fill and refine the voids and capillary pores in the thermal insulation mortar. Therefore, when the amount of fly ash is not large, the strength increases. However, when the amount of fly ash is too large, the amount of cement as a source of strength is small, which affects the strength of the thermal insulation mortar. Therefore, in the foam-EPS thermal insulation mortar system, the optimum dosage of fly ash is 10%. The relationship between the density and thermal conductivity of 35 foam-EPS insulation mortar is indirectly reflected by the apparent apparent density of the same material. The porosity of the material generally decreases as the dry density decreases. The foam-EPS insulation mortar is a multi-porous composite system composed of a variety of materials, and has an optimum dry density, so that the thermal conductivity of the thermal insulation mortar is minimized. If the dry density of the foam-EPS insulation mortar is too small, the porosity is too large, and the internal voids will be connected to each other due to the relative lack of cementing materials in the system, resulting in an increase in the thermal conductivity of the thermal insulation mortar, compressive strength and flexural strength. reduce. Therefore, the dry density of the foam-EPS insulation mortar of this test is controlled to a minimum of 190kg/m3. After comprehensive utilization of the comprehensive utilization of the desulfurization ash of the circulating fluidized bed boiler of Neijiang Power Plant, the cold storage (China Huadian Neijiang Power Plant 641006). quality. Cost and scientific basis, and analysis of the social and economic benefits of the comprehensive utilization of fly ash.

The circulating fluidized bed boiler (CFBC) is a relatively advanced clean combustion technology commonly used in the world to effectively control the emission of sulfur dioxide and nitrogen oxides to air pollution. Neijiang Power Plant introduced the operation of a 410t/h circulating fluidized bed boiler in Finland, which not only controls the pollution of the atmosphere caused by high-sulfur coal power generation, but also reduces the discharge of wastewater. This is the “double control zone” of acid rain and sulfur dioxide. In the southern region, it is important to ensure the coordinated development of its economy and environmental protection. However, due to the incorporation of limestone in the combustion, the circulating fluidized bed boiler produces more ash than conventional conventional furnaces. Under normal conditions, the operation will produce about 100,000 tons of desulfurized ash per year, which is densely populated. In the south of Sichuan Province, the single factor analysis will be carried out. Under the conditions of various additives, bubbles and EPS, the thermal conductivity of foam-EPS insulation mortar can be reflected from the perspective of ensuring dry density. The relationship between the dry density and thermal conductivity of foam-EPS insulation mortar is shown in Table 6. Table 6 Relationship between thermal conductivity and dry density of foam-EPS insulation mortar Thermal conductivity / W / (m is seen in Table 6, with foam - EPS insulation The dry density of the mortar increases, and the thermal conductivity of the material increases. In order to meet the requirements of the thermal conductivity of the thermal insulation material not greater than 007WAm.K), the dry density of the foam-EPS thermal insulation mortar must be controlled to be no more than 240kg/m3. 4 Conclusions (1) One of the key technologies for the production of foam-EPS insulation mortar is the preparation of foam. In order to obtain a foam with good performance, a CCW-2004 type foaming agent was selected. (2) The feeding sequence of the raw materials and the length of the stirring time have great influence on the performance of the foam-EPS thermal insulation mortar. The first collection date: 2005-foam and cement slurry are mixed and stirred for 60s, and then stirred with other components for 30s. It can produce a uniform, independent and fine thermal insulation mortar.

(3) EPS and bubble as the thermal material of the foam-EPS thermal insulation mortar system, the suitable volume ratio is 3:7, which can reduce the large pores caused by the single grading of EPS particles, optimize the gradation and improve the pore structure. . Incorporating 10% fly ash (based on the total weight of the cementitious material) can increase its compressive and flexural strength and reduce costs. (4) The thermal conductivity of foam-EPS thermal insulation mortar has a close relationship with the dry density. The thermal conductivity of the thermal insulation mortar can be controlled by controlling the dry density of the thermal insulation mortar. In order to make the thermal conductivity not greater than 007W (mK) foam - EPS insulation mortar dry density should be no more than 240kg / m3.

(Finish)

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