Those craftsmen, one by one, all showed that they were watching a good show, and immediately gathered around, wanting to see what kind of medicine was sold in Yuan Yao's gourd.

After Yuan Yao took out the cement, he was not idle.

Soon, the sand and gravel and stones prepared in advance outside the city were mixed together, and then mixed with some water, which only needed to be manually stirred, and it could be quickly made into simple concrete.

In the era when Yuan Yao lived, there were no mixer trucks to build houses in the countryside, and they basically did the mixing by themselves, which could be completed with a shovel.

He demonstrated it himself, and after mixing it evenly for a while, he found a basket made of bamboo, and poured the evenly mixed concrete directly into the gap in these towers.

Because this is just a demonstration, not a direct construction, Yuan Yao is just teaching these craftsmen how to use cement, so there is no need to pour the entire tower with concrete.

He only had to pour part of it.

After an hour of busy work, the first section of the dilapidated city wall has been completed by Yuan Yao's personal entourage.

The interior of the tower is still filled with large stone blocks, but the outside is made of concrete poured and shaped with some wooden planks to support the frame.

"Okay, this section of the city tower poured with cement is almost there."

"You only need to wait for the concrete to dry, and this section of the tower can be considered to be repaired."

"It's definitely much stronger than the previous castle tower."

Yuan Yao said lightly, and ended his demonstration.

The demonstration just now had a beginning and an end, and those craftsmen seemed very contemptuous and unbelievable at first.

However, with the advent of concrete, concrete mixed with stones and gravel was poured on the castle tower, and the shape of the castle tower was gradually restored, and these craftsmen were a little hesitant for a while.

Could it be that this young boy really understands architecture, and can really complete the entire city tower in three days?

Although they didn't believe it, after seeing Yuan Yao's hands, they didn't dare to refute it for a while, so they could only wait, wait for three days, and see if this section of the city tower looked like what the boy said.

After the city tower was over, Yuan Yao didn't continue to stay here to spend it.

He had other things to do.

First of all, the site selection of Huatuo's side has been determined, and in order to build a high-rise building, the foundation must be laid. Therefore, in the past few days, we have begun to plan the direction and specific size of the construction.

And the builders have already begun to dig the foundation, and it won't be long before the foundation pit will be dug.

Once the foundation has been excavated, it is time to start preparing for construction.

However, building a building is not the same as repairing a city wall.

Repairing the wall does not require embedded steel bars to be used for reinforcement, the wall is still there, but only the gaps are repaired, so it is enough to pour supplementary stones.

But building a building is different, the building is a whole, and if you build a five-story building, it can easily collapse if you don't use steel to reinforce the overall structure.

Even if it doesn't collapse, the house is not earthquake-resistant, and once it encounters some shaking, it will easily collapse.

Therefore, if you want to build a building with more than five floors, you can't do it without steel as support.

But in this era, let alone forging steel bars, even better iron can't be beaten.

Many weapons are made of pig iron, which is some iron ore, which is simply refined, and then beaten into pig iron, which is hard and hard, but too brittle and easy to break.

Whether it is hardness or toughness, steel bars are much better than ordinary pig iron.

Although Yuan Yao knew how to refine steel bars, in a short period of time, he couldn't find enough pig iron to refine into steel, and secondly, he didn't have so much time to do these things.

Therefore, the matter of refining steel bars can only be put on hold for the time being.

Fortunately, although there is no steel bar, it is not that there is nothing to replace the construction of the building.

This thing is bamboo.

It is the bamboo that can be found everywhere in the southern region, and after being cut down, it is split into bamboo chips.

According to Yuan Yao, when the new building materials steel bars were on the market in later generations, because the price of steel bars was high at that time, most residents in poor areas generally could not afford the price of steel bars when building houses, so most villagers would choose bamboo pieces to replace steel bars and concrete to build houses.

There is no doubt that the strength of the bamboo piece is definitely not as strong as the steel bar.

However, the toughness of bamboo is strong enough, and it is more earthquake-resistant than houses built purely with cement concrete, and it only needs to be soaked in tung oil to achieve a certain degree of anti-corrosion, so that bamboo can replace steel bars.

Of course, this is only an expedient measure without steel bars, and when Yuan Yao has time, forging steel bars, and building buildings and city towers, he still has to add steel bars.

In this way, the building can be truly sturdy and lasting.

After calculating this, Yuan Yao began to order people to cut down bamboo, which was to be used to build a new medical school.

Three days passed quickly.

According to the agreement with everyone, Yuan Yao came to the renovated city tower in the south of the city.

Those craftsmen have been waiting here for a long time.

In recent days, the weather has been good, although it is already spring, but the spring rain has not arrived as scheduled, and the weather has been sunny these days.

Yuan Yao just asked people to fence the repaired city tower a little to prevent people from destroying it.

Now three days have passed, and it is time to test how strong the poured tower really is.

In fact, cement building, initial solidification, only two hours of time, is enough, two hours of surface has a hardening effect, but to complete solidification, to achieve the final solidification effect, at least three days.

Therefore, this is also why, Yuan Yao told them at the beginning that he only needed three days to repair this city tower.

It only takes one day to repair, but it takes three days when the cement is poured and completely solidified.

Because of the last performance, this time it was not only those craftsmen who came to watch, but also many people who came to visit.

These people are the people in Shangcai County, these three days, although Yuan Yao did not thoroughly promote his cement, but the last time he made a bet with the craftsmen, it has become a recent event in Shangcai County.

It has also become a talking point in major restaurants and neighborhoods, and almost the entire people of Shangcai County know about it.

Even those who pass by to do business have heard of it.

So this time, there are countless people who come to join in the fun and watch the show.