In this way, the amount of admixture is multiplied by 80% of the water content, and the water content of the admixture is 4 kg, and the base water consumption is 187 kg minus 4 kg, so that the benchmark water consumption becomes 183 kg. Then use the hypothetical bulk density of 2350 kg of concrete minus the weight of water, admixtures, cement and fly ash, which is the total weight of the two aggregates of sand and gravel.

After calculation, the total weight of sand and gravel is 2350-183-4-153-143 to get 1867, which requires the use of the selected sand rate again. Multiply this weight by the sand rate, which is the amount of sand, 784 kg. The amount of crushed stone is 1083 kg by subtracting the weight of sand from the total weight of sand and gravel.

In this way, the amount of all materials is calculated, of course, at this time the work of the mix design calculation has not been completed. Because it is only a theoretical mix ratio for trial matching, it is impossible to obtain the concrete mix ratio that meets both the working performance requirements and the strength requirements.

In the concrete mix design specification, two methods are provided. One is to design three theoretical mix ratios of concrete mix ratio of a certain strength, that is to say, a theoretical mix ratio calculated by Li Liangfeng just now, and the water-cement ratio of 0.05 should be added or subtracted respectively, and then two concrete mix ratios should be calculated. In this way, if the concrete working performance also meets the requirements, three C15 concrete mix ratios with a decreasing water-cement ratio of 0.05 will be obtained, and finally three 28-day concrete strength test values will be obtained.

Some of these 3 test values will exceed the concrete preparation strength, and some may not reach it, so you can choose one of the mix ratios that slightly exceed the preparation strength as the final mix ratio. Of course, this may not be economical enough, because among the three mix ratios, there may be a mix ratio that exceeds the formulation strength and is close to the formulation strength, and the value of exceeding the formulation strength is large or small, if it exceeds 3 megapascals?

At this time, you can choose another method, which is to draw a gray-water ratio diagram to choose the most suitable water-cement ratio. The method is to turn the water-cement ratio of the three mixtures upside down. That is, these three water-cement ratios are removed with 1, so that three gray-to-water ratios are obtained.

Taking the grey-water ratio as the horizontal axis and the concrete test strength as the longitudinal axis, a diagram of the relationship between the ash-to-water ratio and the strength was drawn. Generally speaking, the strength of the three mix ratios will be near an oblique straight line at the point in the figure, so draw an oblique straight line with these three points, and then find the strength point on the longitudinal axis, for example, C15 will find the point of 21.6 megapascals. In this way, you can choose a point slightly greater than this preparation strength, such as 22 or 22.5, and then draw a point parallel to the horizontal axis with this point, and then draw a line perpendicular to the horizontal axis from the point where this straight line intersects with the oblique upward line, and you will get a gray-water ratio corresponding to the preparation strength, of course, at this time, it will be reversed into a water-cement ratio, which is the final water-cement ratio required.

Of course, the mix ratio is calculated with this water-cement ratio, and it is also verified through guò trial match to check whether it can meet the design requirements.

Another method that is not used as a graph is to use interpolation. However, it is generally used less.

Li Liangfeng began to calculate the mix ratio with a water-cement ratio of 0.76, but he was indeed a novice and did not improve the sand rate when calculating.

Qin Haijuan on the side hurriedly reminded him: "Li Liangfeng, there is a problem here. If you take a closer look at the standard, when calculating the concrete mix ratio of 0.05 plus or minus 0.05, it is necessary to increase and reduce the sand rate by one percent accordingly. Do you understand?"

Li Liangfeng took a closer look at the design procedures, and found that he really missed a few words, his face was red, it seems that these standards and specifications really have to be memorized word for word, sometimes missing a word or two. It is possible to make a big mistake.

Under the guidance of Qin Haijuan, Li Liangfeng finally calculated the benchmark mix ratio of C15 pumped concrete.

Of course, in order to finalize the mix ratio, it also needs to be adjusted through trial matching.

Li Ruoyu smiled: "Li Liangfeng." Being able to calculate the theoretical mix ratio so smoothly shows that you still have some foundation and a good understanding. However, it is not enough to have theories, it is necessary to sum up experience through a lot of practice, and sometimes the standards and conclusions of experts are not necessarily correct. As technology evolves, many perceptions are likely to change. ”

Qin Haijuan smiled: "Mr. Li." Then you can tell us about it, so that we can all open our eyes. ”

Li Ruoyu nodded and smiled: "Okay, then I'll just say a few points, just for your reference." ”

Hearing that Li Ruoyu was about to speak, even Xie Zili sat upright, and took out a notebook, ready to record what Li Ruoyu said.

Li Ruoyu said with a smile: "With the progress of technology, in the future, our concrete with small slump and small fluidity will not meet the needs of the market." The development of high-performance concrete is an inevitable trend. In particular, high-performance concrete is a new type of high-tech concrete with high fluidity without segregation and water leakage at a low water-glue ratio, and can be leveled by its own weight without vibration, and is filled with model and wrapped steel bars, and this technology can produce excellent concrete of uniform quality. ”

"The main performance of high-performance concrete is that it does not need to vibrate under its own weight, and it fills the formwork space by itself, which can be used for structures that are difficult to pour or even impossible to pour. The formed concrete structure has good mechanical properties and durability properties. Due to the vibration immunity, high-performance concrete can save labor and electricity, improve construction efficiency, eliminate the danger caused by the noise generated by vibration to the environment, and can solve the problems of leakage vibration, over-vibration and difficult to vibrate in the traditional concrete construction, and can ensure that the position of the reinforcement, embedded parts and prestressed channels is not displaced due to vibration, and can make a large use of industrial waste as admixture, reduce the hydration heat of concrete, improve durability, and have significant technical, economic and social benefits. ”

"As we all know, the first step in formulating concrete is to determine the concrete mix ratio. At present, the method of concrete mix design is generally calculated first, and then tested and adjusted, therefore, the mix calculation is the first link to determine the mix ratio of high-performance concrete. The concrete mix ratio is very different from the ordinary concrete mix ratio, and it is difficult to form a unified design calculation method. In any case, there is no universal concrete mix ratio, but the mix calculation method for the characteristics and laws of high-performance concrete should be able to be found, and it is of great significance to discuss the calculation method of high-performance concrete mix for the research and application of concrete. Therefore, if we want to become a leader in the concrete industry, we need to work hard in these aspects. There is a saying that is very good, that is, the third-rate enterprises do the products, the second-rate enterprises do the brand, and the first-class enterprises do the standards! Our company wants to become a first-class enterprise, so in terms of making standards, we must participate in it and have our own contributions. Li Ruoyu said confidently. (To be continued.) )