There is a huge iron cover in the center of the Zhangshui River, the mouth of the cover is more than half a foot higher than the water surface, around the iron cover, there are boats on all sides, tied with long wood, fixed, on the west side of the iron cover, it is with many boats, a pontoon bridge is built, which is connected to the shore.

There were a lot of pedestrians on the pontoon, and they were transporting sacks to the tin cover, which should have been cement.

Li Zicheng had a question in his heart, this began to use cement, could it be that the sediment in the iron cover has been removed? Don't leave silt, otherwise when the bridge deck is poured in the future, the piers may sag, causing the bridge deck to be unstable.

Tang Ruowang was originally on the boat, saw the cavalry, and knew that Li Zicheng had arrived, so he hurriedly brought Lu Rongda and Yu Xiaoying to the riverbank and came to visit, "The Metropolitan Governor!" ”

"No need to be polite," Li Zicheng waved his hand and said, "How about it, this is the beginning of pouring the bridge piers?" ”

"Dadudu, it has begun to be poured today," Tang Ruowang's eyes flashed with blue-green light, "I've seen it, cement concrete, once compacted, is harder than bluestone, Dadudu, how did you come up with this kind of cement?" I've never heard of it in Holy Rome......"

If you've heard of it, won't you live hundreds of years? Li Zicheng smiled secretly in his heart, but his attention was on the bridge pier, "Mr. Tang, has the silt in the iron cover been cleaned up?" ”

"It's cleared," Tang Ruowang said, "Don't worry, the Metropolitan Governor has done this matter himself!" ”

Lu Rong said loudly: "Dadu Governor, removing the sediment at the bottom of the water is done by the students themselves, and they will never dare to slack off, until the loess layer, the students have dug half a foot!" ”

Li Zicheng looked around the distant mountains, and then he realized that there are many mountains here, all of which are loess structures, and digging into the loess layer should be the so-called keel layer, so he said: "Yes, this is a bridge pier, and it must not be sloppy!" ”

"The student understood," Lu Rongda was affirmed, and he was very happy in his heart, "According to the instructions of the Grand Governor, the student laid sixteen cement piles under the loess layer, which were two meters deep!" ”

Only two meters? Maybe the depth is insufficient, but now there is no machinery, and it is already good to manually dig out two meters on the keel loess, Li Zicheng nodded, "We must record all the data and accumulate a complete set of experience for building bridges in the future!" ”

"Yes, Metropolitan Governor," General Lu Rong spread out the yellow book in his hand, "Metropolitan Governor, all the data and students are recorded!" ”

Li Zicheng was very relieved in his heart, nodded and said: "Rongda, since the bridge piers have been poured, the entire bridge must have been designed, briefly talk about what kind of bridge you designed." ”

"Yes, Metropolitan Governor," Lu Rongda closed the yellow book and said slowly: "First of all, the bridge pier, since the width of the Zhangshui Bridge is five meters, the length of the bridge pier is five meters, but the width is only two and a half meters, in order to reduce the impact of flowing water resistance, the bridge pier is not square, but oval!" ”

Li Zicheng couldn't help nodding, the oval bridge pier was probably from the handiwork of Tang Ruowang, but Lu Rong was only sixteen or seventeen years old, and it was already commendable to be able to think so deeply.

The length of the piers is the same as the width of the bridge, there should be no problems, as for the width of two and a half meters...... Li Zicheng tried his best to recall the shape of the bridge piers in later generations, and felt that it was almost the same, and he was not proficient in these engineering things, but fortunately, this Zhangshui Bridge was also an experiment, even if it was not successful, it could accumulate experience, which was not a big deal.

Lu Rongda continued: "Governor, students prepare, the bridge pier will be one meter above the water!" ”

"Only one meter?" Li Zicheng pondered silently for a moment, "Can steel withstand such curvature?" ”

"Curvature?" Lu Rong was puzzled.

Li Zicheng found that he had missed his mouth, and he didn't explain, but asked, "What is the length of the bridge you designed?" ”

Lu Rong glanced at John Tang and said, "The students and Mr. Tang have passed together, and the length of the bridge is set at thirty-two meters!" ”

"Only thirty-two meters?" Li Zicheng pondered for a moment, and then remembered that there are no large ships now, so the bridge does not need to be too high above the river, and the approach bridge naturally does not need to be too long, if you consider it from the aspect of traffic, the river width of 28 meters, and the width of the bridge of 32 meters should be enough.

It's just that the bridge is only one meter higher than the river surface, and the slope angle has reached 1:16.

Li Zicheng took Lu Rongda's yellow book, drew the structural diagram of the bridge on the book, and marked the slope angle, "The traditional stone arch bridge, the slope angle is generally not more than 1:5, the strength and toughness of the cement bridge are greater than the stone bridge, and the slope angle is at most 1:10, like this kind of bridge with a span of 32 meters, the pier above the water surface must reach at least one and a half meters, and now it is cement, the strength has not been tested, and the pier is above the water surface, at least two meters." ”

"The students have been taught," Lu Rongda marked on the yellow book, "The scholars were worried that the curvature of the bridge deck was too great, which was not conducive to the passage of cars and horses. ”

"It doesn't matter, at both ends of the cement bridge, some approach bridges are extended, and the thickness can also be increased." Li Zicheng drew a simple picture on the yellow book again, and explained orally for a while, and Lu Rong understood it generously.

Yu Xiao has always heard all kinds of anecdotes about Li Zicheng, and in his mind, the Metropolitan Governor is already a god-like existence, and Li Zicheng imparts bridge knowledge, and he should accept it with peace of mind.

Tang Ruowang is different, although he knows that Li Zicheng is well-versed in the past and the present, but he still needs his help in some specific things, such as scientific instruments such as microscopes and thermometers.

But today, it seems that in the construction of the cement bridge, Li Zicheng obviously has a very deep attainment, the height of the bridge pier, not only the increase or decrease of materials, but also involves the strength of the bridge deck, if there is not enough scientific knowledge, no one dares to easily give a conclusion, slope angle, curvature such terms, even from Holy Rome he is unheard of.

He almost forgot the specific content of what Li Zicheng said, but he bowed his hand to Li Zicheng, "The Metropolitan Governor has such a study of bridges, and he has studied the construction of bridges before......"

"Ah...... Mr. Tang won the award," Li Zicheng couldn't tell the source of knowledge, his eyes rolled, and he said: "What's strange about this, I, like Mr. Tang, uphold God's will, haha......"

"Haha, haha......" John Tang had to smile bitterly, and his heart became more and more surprised.

"Let's go to the boat and see what the piers are doing!" Li Zicheng diverted the topic and took the lead in walking towards the wooden boat used as a pontoon.

"Yes, Grand Duke!" Lu Rongda was like a tail, and hurriedly followed, Yu Xiao and Tang Ruowang glanced at each other, and they also followed.

The prisoners of war were busy transporting stones, yellow sand and cement, and the materials were concentrated in the wooden boat closest to the piers, which were mixed and mixed by special personnel, and once discharged, directly poured into the iron cover, and then trampled by the strong men in the iron box.

Li Zicheng observed for a moment and immediately discovered the problem.

"Rongda, this can't be done," Li Zicheng shouted Lu Rong to his side, pointed to the prisoners of war in the iron cover, and said: "Although they tried their best, but the weight of the people is too limited, simply with their feet, it is absolutely impossible to compact the concrete, if there is a gap in the pier, even if it is small, it will seriously affect the quality, and in serious cases, as long as the river and the wind can break the pier!" ”

"Governor, how is that good?" Lu Rongda thought about it for a while, but it was a good idea.

Li Zicheng also has a headache, the cement bridge he built was finally unveiled hundreds of years in advance, and he is not an expert in this area, and he doesn't even know the engineering knowledge.

In later generations, he had seen it on the construction site, in order to prevent internal gaps, vibrating rods were commonly used to vibrate and vibrate the concrete, but unfortunately there is no vibrating rod now, and even if there is a vibrating rod, there is no power supply.

The piers had already begun to be poured, and even if they wanted to renovate them to a structure that would not use electricity, it would be too late.

Li Zicheng thought for a moment, but had to use the "stupid method" and use manpower, he asked the prisoners to first use rebar to tamp the concrete, and then use the stone rammer to build the roadbed.

The four sides of the stone rammer are chiseled out of square holes, stuffed into the wooden plugs, and then tied with ropes, and people stand on the boat outside the iron cover, pull and release, and tamp the concrete, every other layer, tamp once, so that although the pouring speed is slower, the remaining gaps in the concrete will be much less.

Taking advantage of the busy situation of the prisoners of war, Li Zicheng told Lu Rongda that when the bridge deck was poured in the future, a little expansion joints would be left every seven or eight meters of distance, so that the concrete would be deformed due to heat-free # expansion and cold contraction.

Lu Rongda recorded it in the yellow book again, and sighed: "Governor, I was originally prepared to finish pouring the bridge piers in three or five days, but now it seems that the time will be at least doubled, and it can't be poured when it's cold at night." ”

"Can't you pour it at night?" Li Zicheng frowned and said, "Rong Da is saying that this pouring bridge pier will stop work when it gets dark?" ”

Lu Rong Avenue: "Yes, Metropolitan Governor, after dark, the cold is very heavy, how to construct continuously, the quality of concrete will definitely decline, affecting the quality of the bridge pier!" ”

"No, it must be uninterrupted," Li Zicheng flatly refused, saying: "If the construction stops at night, the concrete poured today will not condense the same speed as the concrete poured tomorrow morning, and there will inevitably be a fracture layer, causing the pier to break!" ”

Lu Rong was taken aback and said, "It could be so serious? Students really don't know ......"

"It's just started pouring now, and it's not too late to know," Li Zicheng patted him on the shoulder and said, "Rongda, your body has my greatest expectations, do it well!" ”

"Thank you, students, for your support!" Lu Rong bowed and saluted, but said in his mouth: "The strong men can be divided into several groups, but the night is cold, if it affects the quality of the concrete......"

Li Zicheng thought for a moment, and could only use manpower, "Pour at night, prepare a few more strong men, and let them make a fire next to the mixed concrete, it doesn't have to be too laborious, as long as there is no freezing, the impact on the concrete will not be too great!" ”

"Student understood!" Lu Rongda recorded the main points of Li Zi's generation in the yellow book.

Li Zicheng observed for a long time, and put forward some amendments to Lu Rongda's plan, and then let Lu Rongda be responsible for implementing it.

The cement bridge is different from the cement avenue, which needs to be suspended in the air, and Li Zicheng set up camp near the mouth of the river, from time to time to visit the construction site, or think deeply on the flowing water surface to see if there is anything that needs to be improved.

A day passed unconsciously, although the progress of the project was slow, but the water seepage problem that Li Zicheng was most worried about did not appear, and the pouring matter was carried out smoothly.

By the evening, the strong men were already familiar with the process and were speeding up, Li Zicheng also felt relaxed, He Xiaomi suddenly came over with a piece of paper that was about the size of tofu, and said softly: "Governor, Wang Anping came with an urgent message!" ”

"Urgent message?" Li Zicheng took a look and immediately frowned.