"Your Highness."

Wang Ying stood up, his hands covered in mud were placed where he placed.

He has been concentrating on making mud cannons, and Zhao Xu's speech distracted him.

"This is already the third one, the one in front has failed." Wang Ying pointed at the pool of mud next to him, with a little embarrassed smile.

The mud cannons made according to the drawings are very large in size and soft in mud, so the mud cannons made are easy to crack or break.

Originally, he thought it would be very simple, but after getting started, he knew the pros and cons.

"It's okay, it's a good thing to learn from failure." Zhao Xu said.

The difficulty of clay molds is that they are mixed with mud, and the mud that is mixed with cannot be too soft or too hard.

The soft ones are easy to break, and the hard ones are difficult to shape.

This can only be controlled by them. If they fail a few times, they can only master the temperature.

He looked up and looked around and said, "Where are the iron slag being thrown into it?"

This was what he asked Wang Ying to preserve when he was smelting iron.

The purpose is to use it in the future.

"Your Highness and the officials." Wang Ying stood up and took Zhao Xu to a warehouse inside.

The piles inside are slag left by iron smelting.

At this time, craftsmen kept sending slag.

"Your Highness, what exactly do these things do?" Wang Ying was confused for a long time.

Now that the King of Yan finally mentioned these slags, he couldn't help asking.

"Cement made." Zhao Xu said.

"What is this?" Wang Ying and Zou Rong both showed curious expressions.

"You will know later." He decided to make cement himself, but he was better than to witness it.

Silicate cement, also known as Polante cement, appeared in the mid-19th century.

In the previous period, most people used calcined limestone and then made gypsum-bonded buildings.

Later, when a builder bought limestone, he found that clay was mixed inside, but the firing lime was more bonding than before.

Later, he tried to add volcanic ash, ceramic tiles and other powders, and found that the effect was even more effective.

Finally, he thought of the slag after iron smelting, instead of volcanic ash and other substances, and finally decided on the ingredients of cement.

What Zhao Xu wants to do now is this kind of cement.

He asked Wang Ying to take out some slag and grind it into powder, mix it with clay, and then put it in a kiln to calcinate.

The two of them were determined to see the surprise that King Yan wanted to give them.

Zhao Xu did whatever he asked to do.

More than an hour later, the craftsman took out the powder from the kiln.

This is gray powder, which is contemporary cement.

"Find a few blue bricks and make some sand and water." Zhao Xu said.

After the materials were all arrived, Zhao Xu personally mixed the cement with sand and water.

After stirring it into a paste, he applied the cement to the two bricks and placed it on the ground.

"Okay, let's see you tomorrow. Wang Ying, you have to look forward to it." Zhao Xu said with a smile.

Wang Ying and Zou Rong were still confused when they heard this.

the next day.

Zou Rong came to the Military Affairs Office again, and he found that there were many people surrounding the place where the blue bricks were placed.

After a while, the King of Yan also came over, and the craftsman immediately made a way.

"Zou Gongcao, pick up the bricks on it, try it." Zhao Xu said.

Zou Rong nodded, and he endured the curiosity all night.

He walked over and carefully held the blue bricks above. He then raised them and found that the bricks below were also lifted up.

"Huh." Zou Rong showed a surprised expression, but when he thought that there was mud here, he felt that mud could stick together.

"Take it a little more." Zhao Xu said.

Zou Rong nodded, held a brick in one hand and pulled it out, but he didn't pull it out at once.

Then he held his strength and pulled the two bricks apart.

He now showed a look of surprise, "It's amazing. If you have this thing to build a house, it will definitely be very strong."

"It's only one day. After a week, you can't pull it out." Zhao Xuyu is not shocking, "and this cement has another advantage, even if it's soaked in water, it won't be damaged."

Zou Rong's mouth couldn't close in surprise. The King of Yan's statement shocked him so much.

Wang Ying and Wang Chong also came to watch the fun. The two of them were once again provoked to the King of Yan, and they felt that there were endless magical thoughts in the King of Yan's head.

"If you use cement, sand and stone to mix, this is another stronger thing. You can go back and try it slowly." Zhao Xu said to Zou Rong, "It's no problem to build a workshop house now."

"No problem, absolutely no problem." Zou Rong swallowed.

He wanted to use cement immediately to see how much this thing can be applied.

The effect of cement is well known.

Zhao Xu said to Wang Ying: "Pick out a batch of craftsmen to calcin the cement, these slags are enough."

During this period of time, the Iron and Steelmaking Department accumulated thousands of tons of slag, and the cement produced by these slag took a long time.

"Yes, Your Highness." Wang Ying said.

Nodding, Zhao Xu and Zou Rong came out of the Military Affairs Office.

On the way, Zhao Xu remembered the last time Beidi Qiuzhao was hunting.

At present, he does not have the ability to attack Beidi.

Because the longer the supply line is, the more unfavorable it is for you.

He will be on the defensive position for a long time in the future.

So I have been thinking about countermeasures during this period.

After thinking about it, he felt it was necessary to build a fortress area against Beidi along the Yanshan line with Wu'an County as the center.

Although Yanshan Mountain is large, there are only four or five small paths leading to Yanjun among the mountains.

If a prism built of concrete is built on the paths of these trails, supplemented by artillery, wouldn’t it be possible to block the passage of Beidi to the south?

This kind of bastion is different from an ordinary city.

The structure is to transform a dock from a convex polygon to a concave polygon.

Such improvements allow any point of attacking the castle to expose the attacking party to more than one bastion surface, or even three sides.

The defense side can use crossfire to perform multiple blows on the enemy.

Before artillery, such crossfire power was long-range weapons such as bows and arrows.

If you get on artillery, the enemy will definitely suffer heavy failures when fighting such a bastion.

The imperial court could not do it before, but it was an ordinary fortress to guard such a path but was not effective.

If there are fewer soldiers, they will collapse without fighting.

With more soldiers, the troops will be greatly dispersed, and there must be a large enough city block that can accommodate such soldiers.

Of course, after all, this is a cost issue.

The imperial court would rather let the people of Beidi rob the people every year than spend money and food on it.

Anyway, it will not affect the safety of Dasong.

However, this is different for him.

Yan County and Shanggu County are his fiefdom. From time to time, who can bear it?

Furthermore, without a peaceful environment, how to build internally.

Therefore, he had to build this fortress.
Chapter completed!