Concrete is the most commonly used construction material in the current construction project, reasonable concrete construction, can ensure the function and safety of the building, reduce the probability of potential safety hazards and quality hazards, so it is necessary to combine the actual situation, take appropriate construction measures, reduce the impact of external factors on the construction, so as to ensure that the performance of concrete meets the requirements, and in the actual concrete production, the quality requirements of cement are very important. Therefore, on this basis, a simple study is carried out on concrete production, and then the corresponding cement quality requirements in concrete production are analyzed, aiming to ensure the quality of concrete and ensure that concrete meets actual needs.
1 Study on the characteristics of concrete.
Concrete has a high application value in the actual engineering construction project, which can not only meet the construction needs of the project, but also improve the corresponding engineering quality of the project, so as to ensure the service capacity of the project. However, in the actual service of concrete, it is easy to bring potential safety hazards to the project because of the quality of concrete, so in order to ensure the construction quality of the project, it is necessary to control the production quality of concrete.
In order to play the function and role of concrete, it is necessary to study the characteristics of concrete during the production of concrete, combined with the actual situation of concrete, and, give full play to the characteristics of concrete, ensure that concrete, in the actual service, the corresponding characteristics can be fully reflected, this paper, the characteristics of concrete are analyzed accordingly, aiming to ensure that concrete can play the corresponding function in practical application, and its characteristics mainly include.
1) Centralized production in factories. In the actual production of modern concrete, the concrete produced in bulk has been basically reduced, because the number of plastic concrete scattered in the construction site of mixing and bucket pouring has been relatively reduced, and the contemporary concrete chooses the centralized production mode of the factory, based on the factory production mode, the rapid production of concrete can be realized, and the quality problem of concrete production can also be reduced, but this production mode has led to the relatively large slump of concrete.
2) In actual production, the strength range of concrete is relatively wide, it can be C15 concrete, and can reach C80 concrete, different types of concrete, can be used in different environments, have high utilization value, in actual engineering construction, housing construction engineering, the most commonly used concrete is C25 C30 concrete.
3) The linear relationship between the strength of concrete and cement is no longer the main reason for determining the quality and performance of concrete. However, reasonable control of the strength of cement can obtain concrete with better performance.
4) At this stage, the use of concrete is mainly based on pumping, so in the actual concrete mixing, it is necessary to pay attention to the rheological properties of the concrete, so as to ensure the service capacity of the concrete and reduce the impact of external factors on the concrete.
5) Rational use of high-efficiency superplasticizer, in order to avoid subsequent quality problems of concrete, it is necessary to use high-efficiency superplasticizer reasonably when mixing concrete, so as to reduce the quality problems of concrete and ensure the quality of concrete service.
6) In the actual production of concrete, it does not rely on the variety of cement, but relies on external additives to realize the modification of concrete, and realize the role of concrete. This method has become more and more common, and it can also ensure the quality of the concrete and ensure the service capacity of the concrete. For example, the rheological properties of the cement itself are changed by the water demand, setting time, strength development and deformation properties, gas content, etc., especially the high-efficiency superplasticizer.
7) Low water-glue ratio. Because the effect of mineral admixture on the strength of concrete is obviously dependent on the water-glue ratio, therefore, when the water-glue ratio of concrete is 05. When the admixture is used, it cannot play normally. Therefore, under the premise of not considering durability, the water-glue ratio of C30 and C40 concrete should be controlled, and the water-glue ratio should generally be 05. In this way, the quality of concrete can be guaranteed, the adverse effects of concrete water-glue ratio can be reduced, and the service quality of concrete can be ensured.
8) Reasonable use of compounds. In the actual construction of concrete, in addition to the aggregate to be utilized, but also to the reasonable use of admixture, through the rational use of admixture, can meet the basic needs of the project, to ensure the performance of concrete. In order to reduce the increase in the internal temperature of concrete caused by high-strength cement and large dosages, mineral admixtures can be applied to concrete.
2 Research on the production of concrete and cement quality requirements.
Combined with the actual concrete production, the relevant requirements of concrete production quality and cement quality are studied, and then the corresponding requirements of cement quality are elaborated, aiming to meet the corresponding requirements of actual concrete production, ensure the service capacity and service quality of concrete, reduce potential safety hazards, and reduce potential quality hazards.
2.1 The influence of cement quality on concrete production.
In the construction of concrete, it is necessary to carry out quality control on all materials, through reasonable quality control, the impact of material factors on the quality of concrete can be reduced, and cement is an important material to realize the production of concrete, if the quality of cement can not be guaranteed, it will seriously affect the quality of concrete, so it is necessary to combine the actual situation, reasonably control the quality of cement, and ensure that cement meets the corresponding requirements of concrete production.
2.1.1. The influence of cement fineness.
When the production of concrete, the concrete is required to have the corresponding rheology, and the rheology comes from the influence of cement, and the rheology has a great influence on the construction performance of concrete, and the construction performance of concrete is that after construction, after the concrete is hardened, the quality of concrete has a good guarantee, so that the quality of concrete can be ensured. Cement with an appropriate gradation of coarse and fine particles will have better rheological properties. In this way, the 3 30 m particles in the cement play the main role of strength growth, when "60 m, it means that the particles have no effect on the strength, but can play the role of stabilizing the volume, so the particles of 3 30 m should occupy about 90 of all cement, so as to meet the basic needs of actual construction, in addition, when < 10 m, the particles play the role of early strength, when the particles < 3 m, it means that the particles only have the effect of early strength, so the cement with relatively good rheological properties, its 10 m particles should< 10 amounts, which can not only meet the amount of 3 30 m, but also ensure the performance of cement, so as to meet the basic needs of concrete production.
At this stage, in the production of concrete, China pays attention to the fineness of cement and the particle gradation of cement, and at the same time, while improving the performance of cement, it also controls the slump of cement to avoid the impact of hydration heat, so as to ensure the quality of concrete and the service capacity of concrete.
1) The finer the cement and the worse the compatibility with the external additives: when the concrete is produced, it is necessary to combine the actual situation and use the external additives reasonably, but the use of naphthalene high-efficiency superplasticizer UNF a 5U and cement of different fineness to carry out the compatibility test with the external additives, through the test, it can be obtained, the use of the same water-cement ratio of the net slurry to change the amount of external additives, and then in the stirring, the general stirring should be about 5min, and then in 5min and 60min, The fluidity is tested, so as to obtain the saturation point of the additives and cement of different fineness, the fluidity loss after 1 hour and the amount of mixture that makes the fluidity not lost. Through the test, the corresponding data parameters and the obtained data can be obtained, which can be shown in Figure 1 below.
Combined with the basic situation in the above figure, it can be determined that in the process of the obvious increase of the specific surface area of cement, the solubility of external additives and cement is also relatively reduced. Therefore, in order to ensure the construction quality of concrete, it is necessary to reasonably control the fineness of cement to avoid excessive fineness, resulting in poor compatibility between cement and concrete.
2) the frost resistance of concrete increases with the decrease of the specific surface area of cement: by the way of experiment, the corresponding cement material is selected, and the freeze-thaw cycle times when the weight loss 25 is analyzed at different temperatures, so that the content shown in Figure 2 below is obtained.
Combined with the basic situation of Figure 2, it can be found that the frost resistance of concrete increases with the decrease of the specific surface area of cement. Therefore, in order to ensure the performance of concrete and ensure that concrete has good frost resistance, the fineness of concrete is required to be reasonable, and the surface area of cement can be controlled by controlling the fineness of cement, so that cement meets the basic needs of actual concrete production.
3) The excessively fine cement has a greater cracking sensitivity coefficient: the above content, the higher the fineness of the cement, the worse the frost resistance of the cement, this time, the main research is on the cracking sensitivity coefficient of cement. Through the corresponding test, the basic situation diagram of cement cracking sensitivity can be obtained. This is shown in Figure 3 below.
Combined with the basic situation of the above figure, it can be found that there is an obvious relationship between the sensitivity of cement and the fineness of cement, when the value of fineness is smaller, the cement will be cured for 14 days, and the number of days of cracking will be higher in the environment of 20 degrees. Therefore, in order to ensure the performance and quality of concrete, it is necessary to reasonably control the fineness of cement to avoid the worse the crack resistance of cement.
4) The influence of cement fineness on cement slurry and concrete cracking: combined with the actual situation, it can be found that the fineness of cement not only has other effects on concrete, at the same time, in the actual service, fineness will also affect the cracking of concrete, and the cracking degree of cement with different fineness is also obviously different. Through the test comparison, it can be found that the specific surface area of the cement, in the actual service, after drying, the cracks presented by the cement are also obviously different. After experimental research, it was determined that the number of cement cracks with a concrete specific surface area of 220 was more, followed by 320, and 490 was relatively worse.
It can be seen that cement of different fineness has an obvious impact on concrete cracking, so in order to ensure the production quality of concrete, the fineness of cement needs to be reasonably controlled to ensure that the fineness is reasonable.
2.1.2. The strength of cement.
Cement is the basis in the production of concrete, in order to ensure the quality of concrete, the strength of cement needs to be reasonably controlled, after the cement strength of the water-cement ratio increases, the provisions of the nominal strength of the cement, but still to the same before the revision of the water-cement ratio is low, so, in the past 30 years, China's cement 8D plugging has increased by about 20MPa, relative to the 28D strength of the early strength increase is greater.
Continuously improve the cement strength technology, is to increase C3S and C3A, improve the specific surface area of cement and other measures on the basis, so that the high strength and early strength components in the cement increase, in addition, because the specific surface area is not the upper limit, so it can be appropriately increased, but the heat of hydration will be relatively increased, so that the crack resistance and corrosion resistance of concrete will be relatively reduced, and then affect the performance of concrete.
2.1.3 Other questions.
1) Alkali content. When the concrete aggregate is active, it will have an impact on the reaction of concrete alkali aggregate, and the aggregate itself does not contain alkali activity, and the alkali content is too large, it will affect the crack resistance of concrete, and even affect the related structure of concrete, which is not conducive to the reasonable work of concrete.
2) Factory temperature. In the actual production of cement, if the temperature of the factory is too high, and after being transported to the mixing plant, the temperature is not reasonably lost, which will lead to the cement after feeding, the temperature is still high, so that the temperature of the concrete will be affected, and in this case, it is easy to cause the temperature difference between the inside and outside of the concrete, and then it is easy to cause the problem of cracks in the concrete, which is not conducive to the rational use of concrete. In order to achieve the quality of this problem, it is necessary to pay attention to the temperature control during pouring to ensure that the temperature is reasonable and reduce the chance of temperature stress.
3) Cracking susceptibility. The cracking sensitivity is obviously different from the cement variety and the cement manufacturer, so before the cement leaves the factory, it is necessary to do a good job in the crack resistance inspection of the cement, and make the corresponding labeling according to the test results, so that the cement can take corresponding control measures according to this part of the data in the actual application, so as to ensure the performance of the concrete and reduce the impact of cracks.
4) Grinding aids for cement. At this stage, many enterprises will use grinding aids in the production of cement, because the components of grinding aids have diversified characteristics, so after the use of grinding aids, cement and concrete should be tested and studied accordingly to ensure that cement has good performance requirements.
2.2. Research on the requirements of cement quality in concrete production.
Combined with the above situation, it can be found that concrete is affected by the factors of cement, so in the actual concrete production, as long as the quality control of the factors affecting the concrete is carried out, the quality of the concrete can be guaranteed, the performance of the concrete can be ensured, and the probability of the occurrence of hidden dangers can be reduced.
2.2.1. Requirements for cement fineness.
Combined with the above studies, it is found that cement fineness not only has an impact on the crack resistance, frost resistance and compatibility of external additives of concrete. Therefore, in the actual concrete production, it is necessary to do a good job in the control of cement fineness, and choose the cement with suitable fineness, which can ensure the construction quality of concrete, reduce the impact of external factors on concrete production, and ensure the service capacity of concrete.
2.2.2. Requirements for cement strength.
Cement strength also has a significant impact on concrete, therefore, in the production of concrete, it is necessary to do a good job in the strength control of concrete, reasonable cement strength selection, can ensure the strength control of subsequent concrete, reduce external factors, have an impact on the strength of concrete, and ensure the service capacity of cement.
3 Quality control during concrete application.
In order to meet the production needs of concrete, in the production of concrete, it is necessary to do a good job in the quality control of concrete raw materials, mainly to control cement, aggregates, etc., to ensure that these raw materials have good performance and gradation, and to meet the needs of actual construction. In addition, before concrete production, it is necessary to design the mix ratio in combination with the site environment to ensure the reasonable control of water content, so as to meet the construction needs, reduce potential safety hazards, and ensure the service capacity of concrete.
Hotspot Engine Program
4 Epilogue. Combined with the actual situation of concrete production, this paper first analyzes the characteristics of concrete, and then analyzes the production of concrete and cement quality requirements, first analyzes the impact of cement on concrete, and then combines the impact to take effective control measures to ensure the production quality of concrete, so that concrete can play a corresponding role in the subsequent construction, so as to meet the basic needs of construction, ensure the quality and safety of related projects, and reduce the adverse effects caused by quality hazards.