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Conditions and feasibility of mixing station transformation to produce wet mixed
Update time：2017-09-08 00:37:22clicks：1905次Type size：T|T
Concrete mixing station transformation production of wet mix mortar has unique advantages, such as the same raw materials with concrete, similar production process, customer resources and so on. However, to investigate whether a mixing station is suitable for the production of wet mixed mortar, the following factors should also be considered:
Wet mixed mortar and dry mixed mortar are both pre-mixed mortar, but in the early stage of promotion, there is a distinct difference between the north and south regions, because the climate in the south is wet, mortar water retention time is longer, wet mixed mortar promotion and application effect is better, while in the north, there is little rain, mortar water loss is faster, resulting in the dry mixed mortar promotion and popularization. Although with the progress of additive technology in recent years, the water retention performance of wet mixed mortar in northern arid areas has also been greatly improved, the construction convenience of dry mixed mortar, the long setting time of wet mixed mortar, the slow water collection on the upper wall, and the characteristics of the need to change and adapt to the new construction technology have restricted the market's acceptance of wet mixed mortar.
2 Investigate whether there is a high-quality sand source in the area
The key factor restricting the quality of wet mixed mortar is not the gelling material, nor the admixture, but the quality of fine aggregate. Compared with the method of drying fine aggregates first and then sieving for dry mixed mortar, the fine aggregates used in the production of wet mixed mortar in the mixing station are mostly from the same source as the fine aggregates used in the production of concrete, which are all river sand. When river sand is directly used to produce wet mixed mortar, a small number of stones and mud which do not affect the quality of concrete will seriously affect the quality of wet mixed plaster and masonry mortar. Therefore, looking for high-quality sand source and mastering the secondary treatment method of river sand are also factors that must be considered before the transformation of mixing plant to produce wet mixed mortar.
3. Consider whether there are conditions for the modification of admixture pipelines
Different from the admixtures used in the production of concrete, the admixtures used in the current relatively mature wet-mixed mortar production process are mainly divided into two kinds: plasticizing water-reducing agent and opening time regulator, which play the role of mortar thickening, water retention and adjustment of construction time respectively. In order to prevent the mixing of mortar special admixtures with concrete admixtures in production, before the mixing station transforms to produce wet mixed mortar, it should be considered to transform the existing admixture pipeline and add two special admixture tanks and two special pumping pipelines. In addition, due to the small amount of single admixture of wet mixed mortar and the different amount of two admixtures, in order to prevent excessive admixture from affecting the quality of wet mixed mortar during production, the sensitivity of admixture weighing should also be adjusted.
4 Consider whether you have the ability to guarantee the production of special lines
The stone content of wet mixed mortar directly affects the quality of masonry and coating mortar and the construction experience of front-line workers, and indirectly affects the popularization and application of wet mixed mortar. In the production process of wet mixed mortar, the source of stones is not only a small number of stones in river sand, but also stones introduced into the production of concrete, such as wrong material on the forklift, mixer and tank car are not cleaned. Therefore, in order to ensure the production quality of wet mixed mortar, the mixing station should make a trade-off between concrete production and mortar production, and give priority to ensuring the special line production of wet mixed mortar.
Compared with dry mixed mortar, wet mixed mortar has the advantages of energy saving and environmental protection, stable quality, labor saving, etc., with the prominence of environmental problems and the increase of the site ban, the market share of wet mixed mortar will gradually increase. At this time, if the concrete mixing station can combine its own conditions, fully consider the market, sand source, admixture and special line production and other factors, timely launch wet mixed mortar products. It will be able to enhance its own production capacity and smoothly achieve transformation and upgrading.
Chen Chao (Engineer, Xiamen Building Research Institute Group Co., LTD.)
Under the promotion of the basic national policy of resource conservation and environmental protection, and the promotion of the development of bulk cement and building energy efficiency policy, ready-mixed mortar as an efficient, energy-saving and environmentally friendly building material is the inevitable result of the development of the construction industry. As a category of ready-mixed mortar, wet mixed mortar provides an important guarantee for improving building quality, reducing cost, improving efficiency, reducing environmental pollution, comprehensive utilization of resources, and promoting green buildings. Nowadays, in the face of the construction industry situation, the excess capacity of commercial concrete in some areas has become increasingly prominent, and many enterprises are facing the problem of transformation and upgrading. Wet mixed mortar and concrete have a certain similarity, and has not been opened in most parts of the country, so the production of wet mixed mortar is a direction.
According to the provisions of the national standards GB/T 25181-2010 "Ready-mixed mortar" and GB/T 14902-2012 "Ready-mixed concrete", Table 1 shows the permissible deviation in the measurement of wet mixed mortar raw materials and the permissible deviation in the measurement of ready-mixed concrete raw materials. It can be seen from Table 1 that, compared with ready-mixed concrete, wet-mixed mortar has the same allowable deviation as ready-mixed concrete except for the large measurement deviation of water and admixture per plate. Meanwhile, according to GB/T 25181-2010, a mixer in accordance with GB/T 9142-2000 Concrete Mixer shall be used for the production of wet-mixed mortar. Therefore, wet-mixed mortar can be produced using the metering system and mixing system for the production of ready-mixed concrete. However, GB/T 25181-2010 stipulates that "the mixing time of wet mixed mortar (from the completion of all materials) should not be less than 90s", GB/T14902-2012 stipulates that" for the use of mixing trucks to transport concrete, the mixing time of concrete in the mixer should meet the requirements of the equipment manual, And should not be less than 30s(from the completion of all materials)", so the production of wet mixed mortar should be adjusted to extend its mixing time. Due to the large amount of one-time sand used in the production of wet mixed mortar, the weighing and capacity of fine aggregate scale and hopper should be increased respectively. In summary, according to the characteristics of wet mixed mortar, the transformation of ready-mixed concrete production line to produce wet mixed mortar is mainly reflected in the following aspects :(1) the fine aggregate yard is closed, the sand moisture content is controlled, the relatively dry sand is used to reduce the quality fluctuation, and the fine aggregate yard and the lower bunker are not mixed with gravel and other debris larger than 4.75mm; (2) Increase the water retention thickener and setting time regulator storage pool (tank); (3) Debug the host and extend the mixing time of the machine; (5) According to needs, increase the weighing and capacity of fine aggregate scales and hoppers, increase limestone powder silos, etc.
The "three wastes" include waste residue, waste water and waste gas. The waste residue produced in the production process of wet mixed mortar is mainly composed of waste mortar, residual material of transport vehicle, residual material of mixer, etc. The points of producing waste water mainly include cleaning the tank body of the transport vehicle and cleaning the mixer; The production of wet mixed mortar basically does not produce waste gas, only produces dust, dust is mainly generated by the storage yard, silo, feeding system, feeding system, mixing system and other parts, these parts are closed and dust removal treatment, so there is no dust emission. Taking Xiamen Tianrun Jinlong Building Materials Co., LTD., a subsidiary of Xiamen Institute of Building Science Group Co., LTD., as an example, the waste slag and waste mortar produced by the production of wet mixed mortar are separated from sand and wastewater by sand and stone separator, and the separated sand can be used for reproduction. The generated waste water, together with the waste water produced by the cleaning transport vehicle and the cleaning mixer, is stirred by the relay tank and transported to the filter press, and the filter slag and water are obtained after the press filter. The water can be used for production, cleaning the factory floor, sprinkling water and dust removal, cleaning vehicles, etc. The filter slag can be used in the preparation of landfills and autoclaved aerated concrete blocks. Therefore, the production process of wet mixed mortar can still achieve "zero emission" to achieve clean production and green production in the plant.
Cui Xin (Engineer, Shandong Jianze Concrete Co., LTD.)
1 Opportunities for concrete enterprises to improve themselves
Opportunities and challenges coexist. At present, in the context of the winter in the construction industry, it is hoped that more enterprises will respond to the national strategy of innovation-driven development, and add fuel to the technological upgrading of the construction industry and the self-promotion of the ready-mixed concrete industry.
1.1 Eliminate backward production capacity
Taking Jinan ready-mixed concrete industry as an example, in 2015, there were 64 ready-mixed concrete enterprises in Jinan with an annual output of 20.6 million cubic meters of ready-mixed concrete, with an average annual output of 322,000 square meters per ready-mixed concrete enterprise, that is, an average monthly output of 26,800 square meters and an average daily output of 880 square meters. They produce less per day. In this context, all localities should take the opportunity to eliminate a number of enterprises with low output and unreliable quality, support several large-scale enterprises with stable quality, considerable output and advanced technology, and lead the benign and healthy development of the ready-mixed concrete industry.
1.2 Increase the added value of ready-mixed concrete
Ready-mixed concrete enterprises give people the feeling is dirty, messy, no technical content, pure processing plants. In the case of disorderly competition in the pre-mixed concrete industry, malicious price pressure and malicious competition by reducing the quality guarantee rate, some enterprises should increase technical investment, improve the added value of concrete, improve competitive strength, and take the opportunity to promote the transformation and upgrading of the ready-mixed concrete industry. Such as the development of precast components, concrete recycling.
2 Prepare for wet mixing mortar
Before taking the road of pre-mixing, wet-mixed mortar should make preparations in the early stage, rather than only prohibiting the administrative coercive policy such as on-site mixing.
2.1 Standard set of inspection standards
At present, the larger use of mortar is mainly masonry mortar, plastering mortar. The quality control and quality testing standards of these two mortar products should be established first, such as how to evaluate the strength of M20 masonry mortar products? Another important feature of wet mixed mortar is the long final setting time. Is the current detection method of mortar setting time suitable for this kind of ultra-long setting time wet mixing? Do not forcibly promote wet mixed mortar, can not carry out wet mixed mortar quality control.
2.2 First pilot, raise the threshold
Before the implementation of wet mortar, it is recommended to choose a few willing, strong technical strength, strict quality control, representative enterprises to try first, accumulate practical experience, improve control standards. At the same time, in the case of ensuring sustainable competition in the industry, the entry threshold of the wet mixed mortar industry is raised to prevent vicious competition.
3 Feasibility of transforming mixing station to produce wet mixed mortar
3.1 Transformation Conditions
The production equipment and raw material selection of wet mixed mortar are relatively close to that of ready-mixed concrete, and there are no restrictions on the promotion, only need to increase the sand screen and measuring equipment.
3.2 Feasibility of transformation
It is feasible in technology and policy for ready-mixed concrete enterprises to transform to produce wet mixed mortar. After the implementation of centralized production, the quality of mortar can be better controlled, but on the basis of fully analyzing the problems encountered along the way in the ready-mixed concrete industry, the steady implementation of wet mixed mortar is not in a hurry.
Qi Yongjun (Chief Engineer, Danyang Heda Concrete Mixing Co., LTD.)
The main materials of wet mixed mortar are cement, fly ash, mineral powder, sand, thickening agent, mixing water, these concrete mixing stations can usually be detected, in the concrete mixing station directly produce wet mixed mortar, for personnel, equipment and other aspects, need to make some simple adjustments.
Advantages of mixing plant transformation :(1) There is no need to increase personnel, only need to carry out relevant training can be on the job operation. (2) The test equipment does not need to be increased in complete sets, only need to buy part of the mortar equipment (such as mortar mixer, consistency meter, etc.), you can directly test. (3) There is no need to change the mixing machinery, and the original concrete production equipment can be directly mixed. (4) Transport vehicles do not need to be increased, and can be directly used for the transportation of wet mixed mortar. (5) Storage of raw materials, only need to separate the mortar with sand can be stacked, there is no need to add another site. (6) The material does not need to be dried, saving energy and reducing consumption. (7) By adjusting the setting time of mortar, it can be transported to the project site after pre-production, without affecting the subsequent concrete production work.
The production process of mortar needs to pay attention to :(1) mortar sand, need to have a special silo to store, and need to have a sand screening machine to screen out. Avoid the inclusion of large particles such as pebbles, which will affect the performance grade construction of subsequent mortar. (2) The thickening agent for mortar needs to have a barrel inventory, the amount of less needs to be added manually, the amount of large can be placed in the barrel inventory, and the computer measurement. (3) During the production process, pay attention to the situation of mixing water, control the consistency of mortar, and adjust the setting time and slightly increase the consistency of mortar for a long construction time; For mechanical construction, the condensation time can be appropriately reduced, and the construction consistency can be strictly controlled to avoid the phenomenon of tube blocking and wall difficulty in pumping. (4) In the concrete production process, if it is necessary to produce mortar, the inside of the mixer can be cleaned in advance to avoid coarse aggregate mixing. (5) When using the mechanical wall, if the pump dedicated to mortar is used, it needs to be carried out in strict accordance with the operating manual.
Yao Lian (Manager of Technical Department, Guangdong Long Sand Washing New Materials Co., LTD.)
Data from the National Bureau of Statistics show that in 2011, China's commercial concrete production was 742.71 million cubic meters, an increase of 27.2%; In 2012, China's commercial concrete output was 888.17 million cubic meters, an increase of 19.6%; In 2013, China's commercial concrete production was 1169.6 million cubic meters, an increase of 31.7%, in 2014, China's commercial concrete production was 1554.13 million cubic meters, an increase of 32.9%. In 2015, China's commercial concrete output of 164.131 million cubic meters, an increase of 2.1%, the growth rate fell 9.3 percentage points year-on-year. In 2015, under the environment of a series of intensive national policies, driven by strong demand in the domestic market, China's commodity concrete industry as a whole achieved steady growth, but the growth rate of production capacity declined significantly, and the annual capacity utilization rate continued to decline. As shown in Figure 1 below.
In the face of the slowing growth of the construction market and the situation of concrete overcapacity, the transformation and upgrading of the mixing plant is required by The Times. The problem in front of the commercial concrete industry comes, how to transform and upgrade the mixing station? Mixing plant where to go? Today, wet mixed mortar is a hot topic, but also the commercial concrete industry concerned about the direction.
GB/T 25181-2010 "Ready-mixed mortar" in the definition of wet mixed mortar is cement, fine aggregate, mineral admixtures, admixtures, additives and water, according to a certain proportion, in the mixing station after measurement, mixing, transported to the use of the site, and used within the specified time of the mix. From a professional point of view, wet mixed mortar belongs to stone-free concrete, which is a product of commercial concrete; From the perspective of production technology, wet mixed mortar is also measured and mixed in the mixing station; From the scope of practical application, according to the data of the China Bulk Cement Association, at least 19 provinces in the country have used mixing stations to produce wet mixed mortar. Therefore, no matter from the perspective of professional, production process and practical application, wet mixed mortar is suitable for the transformation and upgrading of mixing stations. However, whether the mixing station in each region is suitable for the transformation of wet mixed mortar production, this problem needs to be gradually analyzed.
In June 2007, the Ministry of Commerce, the Ministry of Public Security, the Ministry of Construction, the Ministry of Communications, the General Administration of Quality Supervision, Inspection and Quarantine, and the Environmental Protection Administration issued a notice prohibiting the on-site mixing of mortar work in some cities within a limited period, and the promotion of ready-mixed mortar in China kicked off. In these years, the promotion of ready-mixed mortar in our country has been increasing, and the number of forbidden cities and regions has been increasing. However, there are still some cities and regions to promote the implementation of ready-mixed mortar is not enough. The first factor of whether wet mixed mortar is suitable for the transformation production of mixing stations in various regions is to look at the ban policy of the region, the promotion of ready-mixed mortar in the region and the development direction of ready-mixed mortar. The second factor: the new wet mixed mortar originated in Guangdong Province, in 2010 began to apply and promote in the market, wet mixed mortar as a new product, new technology, new concept of The Times. The popularization and application of new products, new technologies and new concepts requires the crystallization of the collective wisdom of industry personnel in all regions, and requires all regions
Article source： Keyword：
Wet mixed mortar and dry mixed mortar are both pre-mixed mortar, but in the early stage of promotion, there is a distinct difference between the north and south regions, because the climate in the south is wet, mortar water retention time is longer, wet mixed mortar promotion and application effect is better, while in the north, there is little rain, mortar water loss is faster, resulting in the dry mixed mortar promotion and popularization. Although with the progress of additive technology in recent years, the water retention performance of wet mixed mortar in northern arid areas has also been greatly improved, the construction convenience of dry mixed mortar, the long setting time of wet mixed mortar, the slow water collection on the upper wall, and the characteristics of the need to change and adapt to the new construction technology have restricted the market's acceptance of wet mixed mortar.
2 Investigate whether there is a high-quality sand source in the area
The key factor restricting the quality of wet mixed mortar is not the gelling material, nor the admixture, but the quality of fine aggregate. Compared with the method of drying fine aggregates first and then sieving for dry mixed mortar, the fine aggregates used in the production of wet mixed mortar in the mixing station are mostly from the same source as the fine aggregates used in the production of concrete, which are all river sand. When river sand is directly used to produce wet mixed mortar, a small number of stones and mud which do not affect the quality of concrete will seriously affect the quality of wet mixed plaster and masonry mortar. Therefore, looking for high-quality sand source and mastering the secondary treatment method of river sand are also factors that must be considered before the transformation of mixing plant to produce wet mixed mortar.
3. Consider whether there are conditions for the modification of admixture pipelines
Different from the admixtures used in the production of concrete, the admixtures used in the current relatively mature wet-mixed mortar production process are mainly divided into two kinds: plasticizing water-reducing agent and opening time regulator, which play the role of mortar thickening, water retention and adjustment of construction time respectively. In order to prevent the mixing of mortar special admixtures with concrete admixtures in production, before the mixing station transforms to produce wet mixed mortar, it should be considered to transform the existing admixture pipeline and add two special admixture tanks and two special pumping pipelines. In addition, due to the small amount of single admixture of wet mixed mortar and the different amount of two admixtures, in order to prevent excessive admixture from affecting the quality of wet mixed mortar during production, the sensitivity of admixture weighing should also be adjusted.
4 Consider whether you have the ability to guarantee the production of special lines
The stone content of wet mixed mortar directly affects the quality of masonry and coating mortar and the construction experience of front-line workers, and indirectly affects the popularization and application of wet mixed mortar. In the production process of wet mixed mortar, the source of stones is not only a small number of stones in river sand, but also stones introduced into the production of concrete, such as wrong material on the forklift, mixer and tank car are not cleaned. Therefore, in order to ensure the production quality of wet mixed mortar, the mixing station should make a trade-off between concrete production and mortar production, and give priority to ensuring the special line production of wet mixed mortar.
Compared with dry mixed mortar, wet mixed mortar has the advantages of energy saving and environmental protection, stable quality, labor saving, etc., with the prominence of environmental problems and the increase of the site ban, the market share of wet mixed mortar will gradually increase. At this time, if the concrete mixing station can combine its own conditions, fully consider the market, sand source, admixture and special line production and other factors, timely launch wet mixed mortar products. It will be able to enhance its own production capacity and smoothly achieve transformation and upgrading.
Chen Chao (Engineer, Xiamen Building Research Institute Group Co., LTD.)
Under the promotion of the basic national policy of resource conservation and environmental protection, and the promotion of the development of bulk cement and building energy efficiency policy, ready-mixed mortar as an efficient, energy-saving and environmentally friendly building material is the inevitable result of the development of the construction industry. As a category of ready-mixed mortar, wet mixed mortar provides an important guarantee for improving building quality, reducing cost, improving efficiency, reducing environmental pollution, comprehensive utilization of resources, and promoting green buildings. Nowadays, in the face of the construction industry situation, the excess capacity of commercial concrete in some areas has become increasingly prominent, and many enterprises are facing the problem of transformation and upgrading. Wet mixed mortar and concrete have a certain similarity, and has not been opened in most parts of the country, so the production of wet mixed mortar is a direction.
According to the provisions of the national standards GB/T 25181-2010 "Ready-mixed mortar" and GB/T 14902-2012 "Ready-mixed concrete", Table 1 shows the permissible deviation in the measurement of wet mixed mortar raw materials and the permissible deviation in the measurement of ready-mixed concrete raw materials. It can be seen from Table 1 that, compared with ready-mixed concrete, wet-mixed mortar has the same allowable deviation as ready-mixed concrete except for the large measurement deviation of water and admixture per plate. Meanwhile, according to GB/T 25181-2010, a mixer in accordance with GB/T 9142-2000 Concrete Mixer shall be used for the production of wet-mixed mortar. Therefore, wet-mixed mortar can be produced using the metering system and mixing system for the production of ready-mixed concrete. However, GB/T 25181-2010 stipulates that "the mixing time of wet mixed mortar (from the completion of all materials) should not be less than 90s", GB/T14902-2012 stipulates that" for the use of mixing trucks to transport concrete, the mixing time of concrete in the mixer should meet the requirements of the equipment manual, And should not be less than 30s(from the completion of all materials)", so the production of wet mixed mortar should be adjusted to extend its mixing time. Due to the large amount of one-time sand used in the production of wet mixed mortar, the weighing and capacity of fine aggregate scale and hopper should be increased respectively. In summary, according to the characteristics of wet mixed mortar, the transformation of ready-mixed concrete production line to produce wet mixed mortar is mainly reflected in the following aspects :(1) the fine aggregate yard is closed, the sand moisture content is controlled, the relatively dry sand is used to reduce the quality fluctuation, and the fine aggregate yard and the lower bunker are not mixed with gravel and other debris larger than 4.75mm; (2) Increase the water retention thickener and setting time regulator storage pool (tank); (3) Debug the host and extend the mixing time of the machine; (5) According to needs, increase the weighing and capacity of fine aggregate scales and hoppers, increase limestone powder silos, etc.
The "three wastes" include waste residue, waste water and waste gas. The waste residue produced in the production process of wet mixed mortar is mainly composed of waste mortar, residual material of transport vehicle, residual material of mixer, etc. The points of producing waste water mainly include cleaning the tank body of the transport vehicle and cleaning the mixer; The production of wet mixed mortar basically does not produce waste gas, only produces dust, dust is mainly generated by the storage yard, silo, feeding system, feeding system, mixing system and other parts, these parts are closed and dust removal treatment, so there is no dust emission. Taking Xiamen Tianrun Jinlong Building Materials Co., LTD., a subsidiary of Xiamen Institute of Building Science Group Co., LTD., as an example, the waste slag and waste mortar produced by the production of wet mixed mortar are separated from sand and wastewater by sand and stone separator, and the separated sand can be used for reproduction. The generated waste water, together with the waste water produced by the cleaning transport vehicle and the cleaning mixer, is stirred by the relay tank and transported to the filter press, and the filter slag and water are obtained after the press filter. The water can be used for production, cleaning the factory floor, sprinkling water and dust removal, cleaning vehicles, etc. The filter slag can be used in the preparation of landfills and autoclaved aerated concrete blocks. Therefore, the production process of wet mixed mortar can still achieve "zero emission" to achieve clean production and green production in the plant.
Cui Xin (Engineer, Shandong Jianze Concrete Co., LTD.)
1 Opportunities for concrete enterprises to improve themselves
Opportunities and challenges coexist. At present, in the context of the winter in the construction industry, it is hoped that more enterprises will respond to the national strategy of innovation-driven development, and add fuel to the technological upgrading of the construction industry and the self-promotion of the ready-mixed concrete industry.
1.1 Eliminate backward production capacity
Taking Jinan ready-mixed concrete industry as an example, in 2015, there were 64 ready-mixed concrete enterprises in Jinan with an annual output of 20.6 million cubic meters of ready-mixed concrete, with an average annual output of 322,000 square meters per ready-mixed concrete enterprise, that is, an average monthly output of 26,800 square meters and an average daily output of 880 square meters. They produce less per day. In this context, all localities should take the opportunity to eliminate a number of enterprises with low output and unreliable quality, support several large-scale enterprises with stable quality, considerable output and advanced technology, and lead the benign and healthy development of the ready-mixed concrete industry.
1.2 Increase the added value of ready-mixed concrete
Ready-mixed concrete enterprises give people the feeling is dirty, messy, no technical content, pure processing plants. In the case of disorderly competition in the pre-mixed concrete industry, malicious price pressure and malicious competition by reducing the quality guarantee rate, some enterprises should increase technical investment, improve the added value of concrete, improve competitive strength, and take the opportunity to promote the transformation and upgrading of the ready-mixed concrete industry. Such as the development of precast components, concrete recycling.
2 Prepare for wet mixing mortar
Before taking the road of pre-mixing, wet-mixed mortar should make preparations in the early stage, rather than only prohibiting the administrative coercive policy such as on-site mixing.
2.1 Standard set of inspection standards
At present, the larger use of mortar is mainly masonry mortar, plastering mortar. The quality control and quality testing standards of these two mortar products should be established first, such as how to evaluate the strength of M20 masonry mortar products? Another important feature of wet mixed mortar is the long final setting time. Is the current detection method of mortar setting time suitable for this kind of ultra-long setting time wet mixing? Do not forcibly promote wet mixed mortar, can not carry out wet mixed mortar quality control.
2.2 First pilot, raise the threshold
Before the implementation of wet mortar, it is recommended to choose a few willing, strong technical strength, strict quality control, representative enterprises to try first, accumulate practical experience, improve control standards. At the same time, in the case of ensuring sustainable competition in the industry, the entry threshold of the wet mixed mortar industry is raised to prevent vicious competition.
3 Feasibility of transforming mixing station to produce wet mixed mortar
3.1 Transformation Conditions
The production equipment and raw material selection of wet mixed mortar are relatively close to that of ready-mixed concrete, and there are no restrictions on the promotion, only need to increase the sand screen and measuring equipment.
3.2 Feasibility of transformation
It is feasible in technology and policy for ready-mixed concrete enterprises to transform to produce wet mixed mortar. After the implementation of centralized production, the quality of mortar can be better controlled, but on the basis of fully analyzing the problems encountered along the way in the ready-mixed concrete industry, the steady implementation of wet mixed mortar is not in a hurry.
Qi Yongjun (Chief Engineer, Danyang Heda Concrete Mixing Co., LTD.)
The main materials of wet mixed mortar are cement, fly ash, mineral powder, sand, thickening agent, mixing water, these concrete mixing stations can usually be detected, in the concrete mixing station directly produce wet mixed mortar, for personnel, equipment and other aspects, need to make some simple adjustments.
Advantages of mixing plant transformation :(1) There is no need to increase personnel, only need to carry out relevant training can be on the job operation. (2) The test equipment does not need to be increased in complete sets, only need to buy part of the mortar equipment (such as mortar mixer, consistency meter, etc.), you can directly test. (3) There is no need to change the mixing machinery, and the original concrete production equipment can be directly mixed. (4) Transport vehicles do not need to be increased, and can be directly used for the transportation of wet mixed mortar. (5) Storage of raw materials, only need to separate the mortar with sand can be stacked, there is no need to add another site. (6) The material does not need to be dried, saving energy and reducing consumption. (7) By adjusting the setting time of mortar, it can be transported to the project site after pre-production, without affecting the subsequent concrete production work.
The production process of mortar needs to pay attention to :(1) mortar sand, need to have a special silo to store, and need to have a sand screening machine to screen out. Avoid the inclusion of large particles such as pebbles, which will affect the performance grade construction of subsequent mortar. (2) The thickening agent for mortar needs to have a barrel inventory, the amount of less needs to be added manually, the amount of large can be placed in the barrel inventory, and the computer measurement. (3) During the production process, pay attention to the situation of mixing water, control the consistency of mortar, and adjust the setting time and slightly increase the consistency of mortar for a long construction time; For mechanical construction, the condensation time can be appropriately reduced, and the construction consistency can be strictly controlled to avoid the phenomenon of tube blocking and wall difficulty in pumping. (4) In the concrete production process, if it is necessary to produce mortar, the inside of the mixer can be cleaned in advance to avoid coarse aggregate mixing. (5) When using the mechanical wall, if the pump dedicated to mortar is used, it needs to be carried out in strict accordance with the operating manual.
Yao Lian (Manager of Technical Department, Guangdong Long Sand Washing New Materials Co., LTD.)
Data from the National Bureau of Statistics show that in 2011, China's commercial concrete production was 742.71 million cubic meters, an increase of 27.2%; In 2012, China's commercial concrete output was 888.17 million cubic meters, an increase of 19.6%; In 2013, China's commercial concrete production was 1169.6 million cubic meters, an increase of 31.7%, in 2014, China's commercial concrete production was 1554.13 million cubic meters, an increase of 32.9%. In 2015, China's commercial concrete output of 164.131 million cubic meters, an increase of 2.1%, the growth rate fell 9.3 percentage points year-on-year. In 2015, under the environment of a series of intensive national policies, driven by strong demand in the domestic market, China's commodity concrete industry as a whole achieved steady growth, but the growth rate of production capacity declined significantly, and the annual capacity utilization rate continued to decline. As shown in Figure 1 below.
In the face of the slowing growth of the construction market and the situation of concrete overcapacity, the transformation and upgrading of the mixing plant is required by The Times. The problem in front of the commercial concrete industry comes, how to transform and upgrade the mixing station? Mixing plant where to go? Today, wet mixed mortar is a hot topic, but also the commercial concrete industry concerned about the direction.
GB/T 25181-2010 "Ready-mixed mortar" in the definition of wet mixed mortar is cement, fine aggregate, mineral admixtures, admixtures, additives and water, according to a certain proportion, in the mixing station after measurement, mixing, transported to the use of the site, and used within the specified time of the mix. From a professional point of view, wet mixed mortar belongs to stone-free concrete, which is a product of commercial concrete; From the perspective of production technology, wet mixed mortar is also measured and mixed in the mixing station; From the scope of practical application, according to the data of the China Bulk Cement Association, at least 19 provinces in the country have used mixing stations to produce wet mixed mortar. Therefore, no matter from the perspective of professional, production process and practical application, wet mixed mortar is suitable for the transformation and upgrading of mixing stations. However, whether the mixing station in each region is suitable for the transformation of wet mixed mortar production, this problem needs to be gradually analyzed.
In June 2007, the Ministry of Commerce, the Ministry of Public Security, the Ministry of Construction, the Ministry of Communications, the General Administration of Quality Supervision, Inspection and Quarantine, and the Environmental Protection Administration issued a notice prohibiting the on-site mixing of mortar work in some cities within a limited period, and the promotion of ready-mixed mortar in China kicked off. In these years, the promotion of ready-mixed mortar in our country has been increasing, and the number of forbidden cities and regions has been increasing. However, there are still some cities and regions to promote the implementation of ready-mixed mortar is not enough. The first factor of whether wet mixed mortar is suitable for the transformation production of mixing stations in various regions is to look at the ban policy of the region, the promotion of ready-mixed mortar in the region and the development direction of ready-mixed mortar. The second factor: the new wet mixed mortar originated in Guangdong Province, in 2010 began to apply and promote in the market, wet mixed mortar as a new product, new technology, new concept of The Times. The popularization and application of new products, new technologies and new concepts requires the crystallization of the collective wisdom of industry personnel in all regions, and requires all regions
Article source： Keyword：
