Li Lei was a little embarrassed after receiving praise from the director.
Li Lei thought to himself, it would be even better if he could be a tester like Xiaopang! Because it seems much easier to be a tester. You only need to do the test well as required, and you don't need to bear such a big responsibility.
Responsibility, and another advantage of being a tester is that you only work day shifts and don't have to stay up late.
But now Li Lei is just thinking about it. After all, not just anyone can be a tester. I heard that Xiaopang and Qian Juan are both relatives of the boss. Without any relationship background, how can they get their turn.
Luo Lianghua asked curiously: "Director, what is the use of this test weight?"
Zhang Jianzhong chuckled and said: "This is a good question. Don't underestimate this parameter. It is a very important indicator. If our actual test volumetric weight deviates greatly from the design volumetric weight, it means that one of our
There is something wrong with the link.”
Zhang Jianzhong patiently explained the importance of concrete density to several subordinates.
Although the standard specifications also have test methods and related explanations, they are still less detailed than Zhang Jianzhong's explanations.
The bulk density of concrete is not only related to the apparent density of the raw materials, but also to the air content of the concrete. This in turn involves concrete admixtures. Generally speaking, air-entraining ingredients must be added to concrete admixtures. If less is added,
Then the bulk density will be relatively high, and the concrete strength will be relatively high, but the working performance will be poor due to the low air content, so this is a contradictory combination.
Of course, the most serious problem is that the air content is too high, which causes a substantial decrease in the strength of the concrete, eventually leading to unqualified concrete strength. This consequence is so serious that Zhang Jianzhong did not go into detail.
Because teaching such a class to newcomers now will scare them.
If the concrete strength is seriously unqualified, it may cause the building to collapse, which may kill people! Of course, if it can be discovered in time, the loss can be reduced a lot.
After completing the bulk density test, Li Lei and Xiaopang began to put concrete into the test mold. This is called the forming test, one of the most important indicators of concrete.
Zhang Jianzhong said with a very serious expression: "Everyone must remember that the strength of our concrete is the most critical indicator. We technicians must take this issue seriously. Those who blindly reduce the excess strength of concrete in order to reduce costs will
It is not advisable. We must ensure that our concrete has sufficient excess strength, especially when doing concrete mix design and testing."
The newcomers all listened carefully.
Zhang Jianzhong continued: "We need to select relevant parameters and calculate our mix ratio based on the concrete mix ratio design specifications and our raw materials. When calculating the trial mix strength, we must pay special attention to the choice of standard deviation. Why?
There are standard deviations and many influencing factors, so the strength of the concrete we produce is unstable and fluctuates within a range. For example, the trial strength of our C30 concrete is 38.2 MPa, but we cannot guarantee that the concrete we produce will
All can meet the standard value!”
Hearing this, Li Lei couldn't help but ask: "Director, why is this? It's so much higher, but there's still no guarantee?"
Zhang Jianzhong smiled slightly and said: "You're surprised, aren't you? You are all college graduates. You should have studied the probability distribution of mathematics, right?"
All four of them nodded. It's one thing to have learned it, but it's another thing to be able to truly understand it.
Zhang Jianzhong drew a simple probability distribution diagram on the ground and continued: "This is the normal distribution diagram in our mix design. Our mix design specifications are clearly written. The strength guarantee rate of the design mix is
Ninety-five percent. In other words, 5% of the concrete we actually produce cannot meet the standard value, because no one can absolutely guarantee it, but this does not mean that these 5%
The strength of concrete can be lower than the value specified in the standard. So everyone must read the standard specifications carefully and understand the deep meaning of each paragraph."
After listening to the director talk so much, Li Lei suddenly discovered that concrete is not as simple as he thought, let alone what ordinary people thought. It is not just a matter of mixing sand, gravel and cement, but it involves a lot of work.
I really learned a lot.
As a concrete operator, he has a heavy responsibility! Li Lei was thinking that he must do a good job and not make any mistakes, otherwise he would be sorry for the job, let alone the director's careful teaching in technology.
The trial matching continued. Although it was quite tiring, everyone was very motivated. This was a rare learning opportunity, which Li Lei especially cherished.
This afternoon, I worked until six o'clock and only did ten sets of experiments. The rest can only be continued tomorrow.
Zhang Jianzhong said with a smile: "Everyone has worked hard. Let's continue working on it tomorrow afternoon. We still have to remove the molds in the morning, and then we will all work together. When we are done with this, I will treat everyone to dinner and let's relax."
Luo Lianghua hurriedly said: "Director, we are not tired, you are the one who really worked hard and taught us so much professional knowledge. I feel that I have learned too much today, more than I learned in the three years of college.
, it’s still useful!”
What a flatterer! The little fat man muttered in his heart and glanced at Luo Lianghua with disdain. You are just an operator and you still want to please the director.
As a native of Suzhou and a relative of the boss, Xiaopang actually looks down on Luo Lianghua and Li Lei. In fact, this is normal. It is normal for Suzhou people to look down on outsiders.
Zhang Jianzhong smiled and said nothing.
Everyone packed up and went home after get off work. Li Lei and Luo Lianghua lived in the factory, went back to the dormitory, washed their faces, and went to eat with their rice bowls.
The dinner was not bad. Luo Lianghua said while eating: "Li Lei, do you think we have a chance to become a tester? I think being a tester is much better than an operator, and you can learn more professional skills from the director. You
Is that right?”
Li Lei nodded and said: "You are right, but we have no chance, so let's do a good job as an operator first."
Luo Lianghua sighed and said, "Oh, we are all migrant workers! If I were a tester, I would definitely do better than that fat man."
Li Lei said with a smile: "Maybe you think too simply. It's not that easy to be a tester!"
Luo Lianghua nodded and said: "Maybe, but I still want to work as a tester. As an operator, I feel inferior."
After all, Luo Lianghua still graduated from a junior college, so it's normal for him to be a little high-spirited.