"What's the matter? That was the first time I had KFC, and the only time! Li Liangfeng said solemnly. This kid is talking nonsense, what kind of first time is that?

"What's that?" Liang Yan pinched her waist and snorted angrily, "According to what you say, it's the first time I've bought a big box, and I haven't used it yet, what do you say?" You pay me! ”

"You've got it, Mengran is very powerful! If she knew, I would have to be dismantled, so you might as well spare me! For the first time, when this effect appeared, Li Liangfeng hurriedly fled in a panic.

"Hey! Stop! Compensate me for the big box? Liang Yan shouted at the door.

"If you don't negotiate, you won't pay!" Li Liangfeng's voice came from the corridor.

Liang Yan stomped her feet hatefully, both deflated and puzzled. I don't look worse than Mengran, Mengran is still a young woman in the industry, it's been so long, why doesn't he like me?

Escaping to get rid of Liang Yan, Li Liangfeng felt a lot more relaxed. Liang Yan is very simple and kind, basically belongs to the heartless guy, can be obsessed with a trivial matter for a long time, or can be silly and happy all day long, the two talk and laugh as usual, which means that everything has passed.

As soon as Li Liangfeng entered the laboratory, he saw that Manager Wu, the representative of the sand and gravel supplier, was talking with the director Qin Haijuan, and the two seemed to be discussing the quality of sand and gravel.

Li Liangfeng was a little weak-hearted, after all, he and Mengran were able to get along because of Manager Wu, and he went to dinner with Manager Wu, and the things that were played in the entertainment venue must not be known to Qin Haijuan and Xie Zili, otherwise he would be finished.

Fortunately, that Manager Wu is also a person who can do things, and when he saw Li Liangfeng coming in, he didn't show his face, but glanced at Li Liangfeng lightly, and continued to talk to Qin Haijuan.

Qin Haijuan saw Li Liangfeng coming, so she shouted, "Li Liangfeng, come here!" ”

Hearing Qin Haijuan's call, Li Liangfeng's heartbeat accelerated a lot, this Manager Wu wouldn't say anything to Qin Haijuan, right?

Qin Haijuan saw that Li Liangfeng looked unrelenting, and said loudly: "Li Liangfeng, what are you thinking?" Silly look, come and take a look at the samples sent by Manager Wu, today you will do another test on the samples they sent to see how the grading of sand and gravel is? There are also important indicators such as the crushing index and mud content of the stone, and we must be careful not to make any mistakes. We have to choose two out of five suppliers, and these test numbers are all important basis for judging, understand? ”

Li Liangfeng nodded and asked, "Didn't you send it last time?" Why do you want to do it again this time? ”

Qin Haijuan said with a smile: "If you are told to do it, you can do it, ask so much!" This sample is not just said once, and it needs to be judged comprehensively by multiple groups of jù, understand? ”

At this time, Manager Wu laughed and said: "It seems that you are still professional, my old Wu is a rough person, but our company is absolutely honest, and the sand and gravel we send is in the Shanghai market, which is definitely the best, you can rest assured!" ”

Qin Haijuan nodded and said, "We believe it, but we still have to speak with the number of experiments." Now we Mr. Li ask us to promote high-performance concrete, and the quality requirements for raw materials, especially sand and gravel, are particularly high. So we have to take it seriously. ”

Manager Wu asked in a daze: "High-performance concrete?" It's the first time I've heard of it! I've only heard of high-strength concrete before, but today it's an eye-opener. Director Qin, why don't you introduce this high-performance concrete to my Lao Wu, it will also facilitate our better cooperation in the future, right? ”

Qin Haijuan nodded and said, "It's okay!" Li Liangfeng, you start doing it first, and listen to it while you do it. ”

Li Liangfeng nodded, and began to use a wok to fry the river sand sample sent by Manager Wu dry, and then do the test.

Qin Haijuan said with a smile: "Manager Wu, the so-called high-performance concrete is developed on the basis of high-strength concrete. It is an important direction for the development of concrete materials in recent years. Our definition of high-performance concrete is: easy to pour and tamper without compromising strength; Good long-term mechanical properties; High strength and good toughness in the early stage; The volume is stable, and the dìng is good; Good long-term performance in harsh environments. ”

Manager Wu said with a smile: "You professionals are different, and we have to strengthen our learning." So what are the high requirements for sand and gravel materials for high-performance concrete? ”

Qin Haijuan nodded and said, "First of all, let's talk about fine aggregates." Fine aggregates should be selected with hard, clean and well-graded natural medium and coarse river sand, and its quality requirements should meet the provisions of the sand and gravel standards for ordinary concrete. The coarseness of the sand has a significant effect on the strength of the concrete, and in general, the coarser the sand, the higher the strength of the concrete. Medium sand with fineness modulus greater than 2.3 should be used for concrete sand preparation of C50~C80, and medium sand or coarse sand with fineness modulus greater than 2.6 should be used for concrete sand with C80~C100. Of course, we still rarely exceed the C50 intensity, but there will definitely be more in the future. ”

Manager Wu laughed again: "After listening to what Director Qin said, I, Wu, also felt that it was an eye-opener!" What are the requirements of the stones? ”

Qin Haijuan said with a smile: "The stone is the skeleton of concrete, so the requirements are also very high. High-performance concrete must be coarse aggregate with high strength, low water absorption and good gradation. It is advisable to choose hard sandstone, limestone, granite, and basalt gravel with rough surface, angular shape, and low needle flake content, and the gradation meets the requirements of the specification. Due to the high strength of high-performance concrete, it is necessary to make the coarse aggregate have a high enough strength, and the general coarse aggregate strength should be 115 times ~ 210 times of the concrete strength or 10% of the crushing index >value. The maximum particle size should not be greater than 25mm, and 10mm~20mm is preferred, because the coarse aggregate with smaller particle size has less chance of internal defects, the bonding area with the mortar increases, and the interface force is more uniform. In addition, coarse aggregates should also pay attention to the grain shape, gradation and rock type of aggregates, and generally adopt continuous gradation, especially limestone gravel with good grading and rough surface. The linear expansion coefficient of the coarse aggregate should be as small as possible, so that the temperature stress can be greatly reduced, so as to improve the volume stability of the concrete. ”

Li Liangfeng just fried the sand dry, and when he heard this, he said: "Director, can this high-performance concrete really be pushed?" ”

Qin Haijuan smiled: "You still don't believe Mr. Li's words? Sooner or later, the impact of architecture on the ecological environment will attract the attention of society. Buildings consume a lot of natural resources and energy in the process of construction and operation, and have different impacts on the environment. Cement, which is the main raw material for the construction industry, is actually an unsustainable product. Therefore, the core of the technology of high-performance concrete is to limit the amount of cement used to achieve high concrete performance, while adhering to its sustainable development principles. (To be continued.) )