The development of foam cement

 Also known as foam cement foam concrete is a porous concrete. It aerated concrete, as in our building has experienced ups and downs on the mileage history of the development. In the past mainly made of porous concrete roof, internal and external wall panels, block and insulation products, high cost, not on-site construction, so in practical engineering applications, has been more restricted. With energy-saving building insulation requirements of the increasing emphasis on environment protection and energy aerated concrete, waste utilization demonstrated certain advantages, therefore, the early nineties of the twentieth century has been considerable development, a great tendency to replace the foam cement. Until recent years, due to the entry of South Korea foam cement equipment to warm insulation layer as a breakthrough, made glow bubble cement new life, but also with aerated concrete in the construction field display their talents, alongside the.
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foam foam foam cement and cement are the main component of foam. the past is the foaming agent in foam concrete under mechanical stirring, the formation of large stable bubbles. The rosin used in foam blowing agents commonly used blood sacrifice hydrolysis of foam. rosin foam with rosin powder, caustic soda dissolved in water (usually the weight ratio of caustic soda: water: rosin = 1:2:4), then with melted glue (hide glue or glue) made of thick resin glue mix, and then use warm water dilution, mixing or the formation of hard stable foam. hydrolyzed animal blood sacrifice of blood increases with caustic soda, hydrochloric acid, ferrous sulfate, water made using diluted when mixed into a stable foam. these two blowing agents in the current view, it generates foam volume and stability are poor, coupled with the use of a mechanical mixing method, the size of bubble uneven, poor performance, in general 300-1200kg/m3 bulk density between the thermal conductivity in the 0.07-0.25 W / (m ? k), compared with aerated concrete, there is no obvious advantage.
recent years, the foam has made considerable progress on Manufacture. Its main categories formed two categories:
1, animal fat foam blowing agents
animal as the main raw material is animal skin, a certain amount of caustic soda (NaOH), hydrochloric acid, sodium chloride and other chemicals, heating solution, dilution filter, while the production of a high-temperature dehydration new blowing agent. It is a pollution-free, pollution-free water-soluble liquid with foam volume, foam, high strength, the advantages of long duration.
2, plant vegetable foaming agent
blowing agent is rosin and sodium hydroxide as the main raw material after saponification reaction. vegetal foaming agent with low cost, large capacity foam, foam persistence, etc., Guangzhou, Baoji, Shanghai and Shenzhen, a production .
from the PH value of the view, often blowing animal alkaline, PH value is about 7-8,; and vegetable foaming agent is often acidic, PH value is about 5-6. In general, PH value is neutral foaming agent is better because it will not affect the performance of cement, but also extend the useful life of equipment. There are also mixed blowing agents. No matter what kind of foam blowing agent and the previous phase ratio, has a greatly improved performance, with the Preparation of the foam cement quality has greatly improved, its performance has far exceeded the same products mm aerated concrete.
II hair foam cement and foam equipment
we all know, the previous bubble foam cement Preparation mainly by mechanical stirring method a bubble, then stir together with cement, concrete solidified to form foam. This making process is not only difficult to create large-scale production, the foam quality is poor, mainly in the bubble sizes, up and down uneven, making it difficult to ensure the uniformity of foam cement. Korean equipment into the country, air foam into the mainstream, that is, The role of the adoption of high-pressure air will be a certain concentration of foaming agent in foam spray tube, and finally the formation of uniform size, diameter of the appropriate bubbles. with this technology, not only to high-volume continuous operation, on-site preparation of the foam cement insulation performance has been greatly improved. because of the insulation properties of insulation materials and the material itself has a lot to capacity and porosity, under normal circumstances, the smaller capacity of the material, the better the insulating effect; the same porosity, the more the gap size smaller, more compact, convection inside the material, the smaller the radiation heat transfer, thermal conductivity is smaller. process improvement, quality improvement, application of the foam cement opened up a vast market.
1, with the hair to warm insulation Preparation of cement foam agent
this equipment in addition to equipment imported from South Korea, the country has several production, including giant rainbow machine: in the industry are more advanced, they can already completely replace the imported equipment. The device will foam, stir , pumping integration, will be made to take the foam cement directly to the operations side, and then gelling (mainly by self-leveling) as the low-temperature radiant warmth of the leveling layer and the insulating layer. This has the speed of construction, construction technology , low cost, good quality, etc., have in some areas have a large area of promotion and application.
2, roof insulation with foam cement manufacturing equipment
the equipment because of larger, more difficult handling, general for construction of a large area, and the preparation of the foam cement consistency is low, capacity, scope of use has been limited. to change the lack of such equipment, and some independent research and development of the small device, weighing only 100-200kg, can be carried to the roof, interior construction. These small devices because they do not transfer device assembly, preparation of the foam cement quality, there has been further improved: smaller size, better thermal insulation properties, but also directly on the roof needed to find a certain slope. done with this small device layer of roof insulation has good insulation properties in addition, there are good water resistance, and some did not do the roof in the case of the waterproof layer, the 24-hour water test can be achieved without the effect of infiltration does not leak.
Third, the development prospects of the cement foam
foam cement at low temperature radiant floor heating as an insulation layer has been widely used, but the entire construction market, which accounted have a very small proportion. according to their unique properties such as good insulation, energy efficiency in building it should play a greater role.
(a) further improve the device can further expand its applications.
currently the most Canton is the insulation between floors, in the near future, the applications will be extended to the ground, roof and external wall insulation, can also be used directly for casting wall.
(b) to develop some new additives used to change the performance of foam cement.
1, modifier: change its mobility, anti-down, so as to meet the needs of different places.
2, water repellent: especially in the roof insulation, add impermeability, also improve the cost performance.
3, fiber works: a small concrete projects fibers to the foam, the foam concrete can significantly improve performance, increase the crack resistance, impermeability.
4, properties of materials :
(1) Cement: Cement industry, with advances in production technology, the average grade of cement is also greatly improved. twentieth century, the sixties, the United States, the average concrete strength of 28 MPa, the seventies to 42 MPa 2000, the concrete strength of 70 MPa has been regarded as ordinary concrete. In our country, the low nineties 275 grade cement has been eliminated, according to national standards, -1999) provides that the cement sub-425R, 525,525 R, 625,625 R, 725R six labels, ordinary Portland cement is divided into 325,425,425 R, 525,525 R, 625,625 R seven label. higher grade cement application, to improve the quality of foam cement played a key role. For example, label 525 with the production of foam concrete cement products, lack of capacity in the case of 300 kg/m3, compressive strength of up to 4MPa above, and its excellent performance is evident.
(2) Other packing: According to different needs, fill in additional gravel, slag, insulation particles, and even straw and other materials to achieve different performance, to meet different needs.
short , as a have a light weight, high strength, heat insulation, water impermeability and other fine performance of energy-saving products, foamed cement will be accepted by more and more people. can be expected in the high-strength lightweight foam cement , complex and energy-saving direction at the same time, their applications will be able to continue to broaden.
as a replacement for the second-generation cement foam machine is undoubtedly a very attractive reason to buy, because the construction cost is not just the pursuit of business, but also processing enterprises in the pursuit of the goal. and this for two years as claimed by some equipment manufacturers to improve equipment, made of cement per cubic foam bubble is also a minus minus dosage. From 2006 to use a foam cement cube after 0.8KG to 0.4KG / cube to the current 0.3KG / cube, so that construction costs continue to decline, and equipment manufacturers for this The only explanation is the result of improved equipment.
send foaming machine screw work is to water and foam blowing agent was mixed into a liquid foaming machine and then by the aerodynamic part of the labeled Foam output to the mixer, while the proportion of water and stir into a slurry of cement delivered to the input mixer mixer, the mixer blade and foam structure by the formation of foam cement to the construction by pouring forward screw location. < br> In a similar way after there is mixing of water and foam blowing agent after the pneumatic part of the solution directly into the bubble reached the mixer, and mixer are also parallel slurry mixing, so that the mixing process the formation of foam cement. and then be pumped or on-site casting. Here's one difference is to remove the foam in the cement mixer to form links. but the general principle of the formation of foam cement is not changed.
again analyze the sent to the mixer, and the foam has been formed by the leaf structure of the formation of foam mixer cement, hydraulic system driven by the piston delivered to the construction of pouring position.
process can be seen from the above, the use of column Plug the pump and replace the screw pump, in essence, nothing changes. Now and then compare the technical performance of the two pumps: piston pump is the highest transmission power under the same conditions, the pump pressure is the highest in a variety of pumps, so regardless of the hydraulic field or in the transportation field, high pressure piston pumps are. But the biggest drawback is that piston flow fluctuations, and is also the largest variety of pumps. The above advantages and disadvantages of the structure are determined by the pump can not fundamentally changed. The same structural features of the screw pump also determine the use characteristics: the advantage of a variety of flow fluctuations is the smallest pump, the output flow of maximum adaptability to the medium viscosity, low volumetric efficiency drawback is, only low-pressure system; structure bulky and power density low. and then analyze the two kinds of pumps used in the foam machines: one with twin piston alternately feeding the feed and discharge, and bore large, in the same traffic large bore of the pump under the premise of desirable low-speed stability make the discharge process is also to reduce transmission line flow fluctuations to curb the damage has determined the role of the bubble, the other hydraulic output, high efficiency, which is its strength. But pillar Plug the pump flow fluctuation can not be eliminated, and the pressure fluctuations due to fluctuations in traffic is one of the main foam damaged; two screw using a continuous feed, export flow volatility is low, the bubble of the damage is very low, but the pressure is low, resulting in small head, high transmission difficulties. screw pump has the advantage of easy maintenance, and before people feel the biggest drawbacks of the screw pump is broken bubble high, this is actually a misunderstanding, the bubble has broken two reasons: First, the strength of the bubble itself, which by the nature of foaming agent, and foaming device-independent. The second is the space where the location of the bubble, and further said that under the pressure of the bubble size, which is determined by the device. The past few years with the continuous improvement of foaming agent, making the foam strength is greatly improved, which makes the foam less than the original because of damage caused by foam greatly improved. look at the equipment, the equipment now used in addition while mixing with the slurry bubble early and then pumping the old machine, but both devices are hydraulic pump or a screw mixer into the foam after the foam did not enter the pump. bubble damage actually depends on the tube in the vertical height Road in the raw materials produced by the weight of pressure and pressure fluctuations generated by the impact of the foam. This is why the transmission floors higher, less material reasons for the bubble. So do not make use of screw breakage increased. sum above: We can only say that the two pumping methods have their own strengths. but as for the foam cement technology, works from the device, said pumping means both the use of the bubble does not have any big difference. As such, it can save the new equipment based on the amount of foam, what is? we touch the industry since 2004, has been used to purchase the foam machine and foam early .2005 year, the first in the industry of Weihai Double Jay worked for new building materials company commissioned by the certificate of new technology in Shandong Province Construction Quality Supervision and Testing Test Center test blocks made of cement foam too dry bulk density, compressive strength, thermal conductivity and other standard testing, then monitoring data for the dry bulk density 400KG / cubic, thermal conductivity 0.087W / (m? k), submission of the test block down conversion amount of blowing agent used per cubic in 2.5KG, the quality of early foam does still not reach the level of foaming agent are some quality, but overall, the foam was made of cement is relatively stable. Later in the amount of foam blowing agent to improve as did several adjustments in July 2005 Yantai, Weihai and other regions by the number of enterprises out of proportion the amount of construction of stable foam in the amount of cement per cubic foam at 1.2KG. with the ratio of cement to make the foam sample after several site inspection, may Shandong Province, out of the data and awarded the double Jie companies try to reduce the amount of blowing agent foaming cement used per cubic 0.8KG (with screw-type pumping equipment, water, cement, foaming agents and other additives and fillers strictly quantitative), but sampling site see the effect of the insulation layer has been made clear as the effect of the use of 1.2KG.
until the even reduced to the amount of cement used per cubic 0.3KG foam blowing agent. So I am in front of the device under the principle of contrast, we can know it works on two foam machines did not essentially change. At the same time here also need to mention as a key factor in the quality of blowing agents in the current market we saw all types of foam, in addition to a very small number of manufacturers introduced the complex multiple and strength in the foam blowing agent there is a certain change, the other the majority of products is hard to say good. Because there is not an authoritative assessment of the standard, we can only use product comparison approach to identify the boundaries of good and bad. but even now these complex type of foam, Contrast double-Jie company stable of products, there is no obvious quality improvement.
in these premises, the province based on what bubble? strictly speaking, so far, do not have any one person can give a make I am convinced the answer, we have repeatedly talked about because of improved equipment performance, but how to improve, it seems that no one can say very thorough. then we can only understand this is a baseless and completely subjective consciousness, or as a marketing tool to adjust the selling point for the additional equipment the amount of blowing agent. because we are faced with a positive phase of the project to go exploring, there is nothing much the standards and norms as a reference, either in the industry are at fuzzy cognitive and exploratory stage. There is no standard and norms for the market, we are naturally a part of which can not strictly controlled. So now the insulation layer is made qualified acceptance of the majority of the construction side and the engineering staff did not know my heart , at the site without a clearly defined standard, although Shandong, Hebei and other provinces already have the relevant norms, but because of many factors, not been implemented in the construction and acceptance. But for the future of national standards to be introduced, and now the place standard test data should be strictly as our part of the construction. If the spirit of the mentality of a quick success or blind obedience, it will directly lead to the neglect of quality.
construction firms are not scientific research institutions, their pursuit of profit maximization is understandable, but as equipment to processing enterprises, the sale of equipment at the same time, should provide a rational for the production of foam cement ratio, and this ratio is the birth of reference should be processing enterprises enterprises or local standards, combined with practice construction technology to develop, but a part of any data which should be detected based on the data subject.
because people lack of knowledge of the foam cement, leading construction companies in the construction of the advantages of foam cement can not be fully play out, and now some acceptance of units tend to focus only strength, the result of low intensity not to be through the acceptance of the insulation layer, in fact, ignored the acceptance of units foamed cement appears as insulation products. No one in the previous board made of benzene intensity is very demanding, then the use of foam when the cement mortar screed, do not press the vision to demand it. After all, the foam is not an ordinary cement concrete, it appears not to load-bearing. with a view of insulation materials look on and use it to play its biggest field in the insulation function.
acceptance in the treatment of cement foam, because it is insulation products, they should be the first element of testing the thermal conductivity, followed by anti- compressive strength and dry bulk density, but one fact is now testing stations around the compressive strength and dry bulk density for the test is relatively easy given the data, while the thermal conductivity of the key factors as means of detection in most parts of the constraints makes the result of the data can not, even if some can detect a large number of testing agencies, the testing costs are relatively high, so people are intentionally or unintentionally, in a most critical element of this rather neglected.
as a replacement for the foam machine made the biggest selling point is the concept of saving the amount of foam, which construction of the pursuit of profit-maximizing enterprises, is undoubtedly a very attractive reason to buy, because the construction cost is not just the pursuit of business, is also the processing enterprises in the pursuit of the goal. and this year some of the equipment with the equipment manufacturers claim that improvement of cement per cubic foam blowing agent is also a reduced amount of minus. From 2006 to use a 0.8 cubic foam cement KG to the future 0.4KG / cube to the current 0.3KG / cubic meters, the construction costs continue to decline, and equipment manufacturers the only explanation for this is the result of improved equipment.
screw feed type foam machine work is to water and foam blowing agent was mixed into the liquid, then the aerodynamic part of the foam machine foam labeled output to the mixer, the same proportion to the water and cement slurry mixed into the input mixer sent to the mixer, the mixer blade and foam structure by the formation of foam cement to the construction by pouring forward screw location.
in a similar way after there is made by mixing water and foaming agent pneumatic part of the liquid foam is made after the bubble reached the mixer directly, but are also simultaneously slurry mixer mixing, so that the formation of foam in the cement mixing process. and then be pumped or on-site casting. Here's one difference is to out the formation of foam cement in the mixer link. but the general principle of the formation of foam cement is not changed.
again analyze the proportion of water, and then after the transfer of aerated foam into the mixer in quantitative, but in proportion to the water and stir into a slurry of cement delivered to the input mixer mixer, and the foam has been formed by the leaf structure of the formation of foam mixer Cement, hydraulic system driven by the piston delivered to the construction of pouring position.
process can be seen from the above, replace the screw using the piston pump, in essence, does not change. Now and then compare the two technical performance of the pump: piston pump is the highest transmission power under the same conditions, the pump pressure is the highest in a variety of pumps, so whether in the field or in the transportation field of hydraulic, high pressure piston pumps are. But Piston the biggest drawback is that large fluctuations in traffic, and is the largest variety of pumps. The above advantages and disadvantages of the structure are determined by the pump can not be fundamentally changed. The same structural features of the screw pump also determine the use characteristics: the advantages flow volatility is the smallest of all kinds of pumps, the output flow of maximum adaptability to the medium viscosity, low volumetric efficiency disadvantage is that only for low pressure systems; structure of heavy, power density is low. and then analyze the two pumps in the foam Machine use: one with twin piston alternately feeding the feed and discharge, and bore large, with the flow in the large bore of the pump under the premise of desirable low-speed stability make the process more discharge pipes can reduce the Road traffic fluctuations, to curb the damage has determined the role of the bubble, the other hydraulic output, high efficiency, which is its strength. But the piston flow fluctuations can not be eliminated, and the pressure fluctuations due to flow fluctuations in the bubble one of the major damage; two screw using a continuous feed, export flow volatility is very low, very low foam damage, but the pressure is low, resulting in small head, high transmission difficulties. screw pump has easy maintenance advantage, and before the screw sense of awareness of the biggest drawbacks is the high rate of bubble breakage, this is actually a misunderstanding, bubble breakage for two reasons: First, the strength of the bubble itself, which by the nature of foaming agent, nothing to do with the foam device. The second is the space where the bubble position, and further said that under the pressure of the bubble size, which is determined by the device. And in recent years with the continuous improvement of foam, making foam strength was very large increase, which made the original due to lack of foam damage caused by foam greatly improved. look at the equipment, the equipment now used by early bubble and then pumping the slurry while stirring the old machine, but whether it is hydraulic or screw After the mixer pump rod devices are soaked into the foam did not enter the pump. bubble is actually broken on the pipeline depends on the vertical height of the weight of raw materials produced in the pressure and pressure fluctuations generated by the impact of the bubble. This is why the higher floors transportation, material inside the bubble, the less reason. so the use of screw does not cause damage to increase. To sum up: we can only say that the two pumping methods have their own strengths. but as for foam cement technology, works from the device, said pumping means both the use of the bubble does not have any big difference. As such, it can save the new device based on the amount of foam, what is? Our contacts in the industry since 2004, has been used to purchase the foam machine and foam early .2005 year, the first in the industry of Weihai Double kit of new building materials for new technology companies who have the certificate of quality of construction in Shandong Province commissioned Supervision and Inspection Testing Center test blocks made of cement foam too dry bulk density, compressive strength, thermal conductivity and other standard testing, when the monitoring data for the dry bulk density 400KG / cubic meters, thermal conductivity 0.087W / (m? k) examination and the test block down conversion amount of blowing agent used per cubic in 2.5KG, the quality of early foam does not yet reached the level of foaming agent are some quality, but in general, when do foam cement is relatively stable. Later in the amount of foam blowing agent to improve as did several adjustments, in July 2005, Yantai, Weihai and other regions by the number of enterprises out of proportion the amount of construction and stable in each the amount of foam cement foam cube in 1.2KG. with the ratio of cement to make the foam sample after several site inspection, the data obtained in Shandong Province was awarded the low temperature hot water floor radiant heating construction technical guidance JD-14-001-2005 0.8KG (with screw-type pumping equipment, water, cement, foaming agents and other additives and fillers strictly quantitative), but look at the sampling site, the effect of the insulation layer has been made clear as the effect of the use of 1.2KG.
until the working principle of the equipment in front of comparison, we can know this works on two foam machines did not essentially change. At the same time also need to mention here as a key factor in the quality of blowing agent, in the current market We see the various types of blowing agents, in addition to a very small number of manufacturers introduced in the foam blowing agent compound and the intensity of a certain multiple of change, the other the majority of products is hard to say good. Because there are no authoritative assessment of a standards, we can only use product comparison approach to identify the boundaries of good and bad. but even now these complex type of foam, compared to double-Jie company stable of products, there is no obvious quality improvement.
in Under these premises, the provincial basis of what bubble? strictly speaking, so far, do not have any one person can give a convincing answer me, we have repeatedly talked about because of improved equipment performance, but how improvement, it seems that no one can say very thorough. then we can only understand this is a baseless, totally subjective consciousness, or as a marketing tool to adjust the selling point for the additional equipment the amount of blowing agent. because we face is a positive walk in the exploration period of the project, nothing much standards and norms as a reference, any party in this industry are in a fuzzy cognitive and exploratory stage. There is no standard and norms for the market, we naturally can not strict control of one of these links. So now the insulation layer is made by qualified majority of the construction side and the engineering staff acceptance of mind is not clear, at the site without a clearly defined standard, although Shandong, Hebei and other provinces already have related specifications, but because many factors, not been implemented in the construction and acceptance. But for the future of national standards will be promulgated, the current local standards in the testing data should be strictly as our part of the construction. If the spirit of a quick success or blind obedience of the mind, it will directly lead to the neglect of quality.
construction firms are not scientific research institutions, they seek to maximize profits is understandable, but as equipment to processing enterprises, the sale of equipment at the same time, it should be made to provide a targeted reasonable ratio of foam cement production, and this ratio is the birth of reference should be processing enterprises enterprises or local standards, combined with the practice of construction technology to develop, but a part of any data which should be based on the detected data subject.
because people lack of knowledge of the foam cement, leading construction companies in the construction of the advantages of foam cement can not be fully played out, now some acceptance of units are often only concerned with strength, the result of the low strength of the insulation layer not be through the acceptance, in fact, ignored the acceptance of units foamed cement appears as insulation products. in the past no one on board has made intensity of benzene is very demanding, then the use of foam cement mortar when you do not click leveling layer of the eye to ask for it. After all, the foam is not an ordinary cement concrete, it appears not to load-bearing. with a view of insulation materials look on and use it to play its biggest field in the insulation function.
Acceptance of cement in the treatment of foam, because it is the insulation product, so the detection of the first element should be the thermal conductivity, followed by the compressive strength and dry bulk density, etc., but one fact is now for the compression testing stations around the strength and dry bulk density of the test is relatively easy given the data, while the thermal conductivity of the key means of the factors detected in most regions can not make the result of the data, even if some can detect a large number of the testing organization, The testing costs are relatively high, so people are intentionally or unintentionally, in this most critical elements tend to neglect.