Roland stood in the backyard of the firing room waiting for the first batch of cement to come out.

This brick house was designed specifically for cement production. It is about fifteen meters long and four meters wide. There is a door in the front and back. The difference is that the front door is as spacious as possible for people to carry materials. The back door is only one person wide, allowing Anna to sneak into the firing room.

For this purpose, he also built a circle of walls at halfway up the house, surrounded the back half of the firing room, and arranged a cavalry to guard the import and export - they were all Carter's subordinates, and their loyalty was unquestionable.

The production process of cement is very simple. After crushing limestone into powder, mixing it with clay and iron powder, calcining the clay material by dry or wet method, and then grinding it with gypsum to use it. The raw materials are very ordinary, and it is difficult to make a large amount of iron powder and can be left unsold. The key lies in the calcination temperature of the clay material.

Roland didn't remember the specific temperature required for firing cement. Even if he remembered, he couldn't measure and control the temperature - both infrared thermometers and thermocouple thermometers were countless times more complicated than cement. He only knew that this temperature was almost similar to the melting point of iron, and the calcination process was also a difficult time in producing cement.

In the era of underdeveloped smelting technology, maintaining the blast furnace temperature has always been a problem that troubles everyone. The heat loss of ordinary open furnaces is extremely large, and it is difficult to keep the furnace temperature above 1,200 degrees. The reflector needs a high-temperature inner liner, so he can't think of how to build refractory bricks for a while. The traditional iron-smelting blast furnace is even worse. The temperature may meet the standards, but relying solely on the narrow and long furnace chamber to calcinate the cement, I am afraid that I will not burn enough when the evil moon has passed.

Therefore, the firing room designed by Roland did not have any heating measures at all, and he relied on Anna.

The small particles of limestone that were artificially broken were mixed with clay and mixed with water to form a slurry, and evenly spread in the firing room. Then the knight locked the door and cleared the handyman. Anna entered through the back door and let the flames bake the slurry on the ground until the iron rods placed in the room melted.

Roland was a little restless, which was his first step to stationing in the border town. If cement could not be made, the plan to build a city wall in three months would be nothing more than empty talk. Without the city wall, I am afraid that no one would be willing to stay in this ghost place. Whether it is real history or fictional literature, if you want to farm well, a stable base is essential.

"Your Highness, can you really stick all the stones together?" Carter Lannis, who was guarding the fourth prince, asked. Although the prince told him that this was the latest research result of the Graycastle Alchemy Workshop, he was still skeptical. After all, those people had never made any truly reliable alchemy products.

"Who knows? That's what they said anyway," Roland spread his hands.

In this world, alchemy and astrology are called the sage art together, and are very popular in mainland countries. The royal family usually trains their own alchemists and astrologers to refine secret medicines and predict fate. For ordinary people, these studies are too high and have a blind faith. Considering this, Roland naturally led the question of the source of cement formula to the alchemy workshop. As for whether the chief knight believes it or not, it doesn't matter at all.

The flames that emerged from the window gradually faded out, and it seemed that they were burned.

Roland stood up and drove Carter out of the yard, waiting alone in front of the back door of the brick house.

The iron door was pushed open with a creaking sound, and Anna walked out with her body. Roland immediately put her robe on her and brought her a glass of water, "How is it?"

The witch's face was gray. Although the wet cement was low in dust, the scorching air during calcination would still bring dust. For her, who could not wear a mask, it would obviously not be too comfortable to stay inside for dozens of minutes. She coughed twice and nodded, "The mud has turned into dust."

Roland couldn't wait to get the temperature lower enough during the firing, so he wrapped the wet towel around his head, grabbed a shovel and drilled into the back door.

The hot air surrounded him instantly. He felt a little difficult to breathe for a moment, and the skin on his hands was sore. Fortunately, it would not take too much time to shovel a handful of dust, otherwise staying in this environment for a few minutes would probably cause high temperature shock.

"Is this what you want?" Anna asked after putting on the witch suit and stretched her head over.

"It looks very similar," Roland flattened the powder and felt its residual heat with his fingers. "If it works, you have to try it out."

“What’s the use of it?”

"There are too many places to use to build houses, bridges, and roads. If it succeeds, people's residences will not be afraid of wind and cold, and they will not be able to destroy them even if they are heavy rain or heavy snow." He patted the girl's head with his other hand, "It was done by you."

Anna lowered her head. I wondered if it was an illusion, but he felt that the girl's breathing had become faster.

According to theory, the fired clinker must be ground with gypsum to adjust its hardening time. But there is no need to consider so much at this time. Roland took a short rest and shoveled out two more hands, then called Carter, who was standing outside the yard, and asked him to prepare cement mortar in the ratio of three portions of ash powder mixed with river sand.

The Chief Knight didn't mind doing some rough work at all. For him, doing such things was much better than fighting for His Highness or hooking up with a noble lady on a trip during Gray Castle.

Since no iron powder was added to the raw materials, the cement slurry was light in color and turned gray and white. Roland poured them all over the stone brick and then buckled the other one. The cement set time was about four hours. Considering the instability of the trial products, he planned to wait until tomorrow to see the results.

The next morning, Roland hurriedly took Carter and Anna to the backyard of the firing room. When he opened the door, he noticed that the cement surface was solidified and closely connected with two stone bricks. The consolidated surface looked uneven, and some of the frost appeared.

Roland squatted down, scraped off the white frost produced by the alkalization reaction, and pressed the hardened cement with his fingers. The touch made him happy - the cement surface was solid and uncomfortable, completely different from the touch after tamping the soil. Even if you use your nails to buckle it hard, you cannot leave a trace on it.

After receiving the instructions from the fourth prince, Carter first tried to lift the stone bricks, but failed. He kicked them hard several times from the side until the junction between the cement and the ground broke, and the two stone bricks were still firmly bonded together. Finally, he waved the hilt of the sword and hit them hard, and could only knock down a small piece of edges and corners.

"Is this the effect of "cement"," Carter immediately realized its effect, "It was incredible. Yesterday it could still flow like a melted candle, and it became as solid as rock in just one night. With this kind of thing, the wall can be built as fast as it wants. As long as there are enough stones, we can even build a wall around the borders within five years!"

"What's the use?" Roland disagreed. "No matter how tall the walls are, they can't stop the enemies from the inside. I would rather turn the dilapidated wooden houses in the border town into solid cement houses so that my subordinates no longer have to worry about falling into a homeless situation after a natural disaster."

"..." The chief knight was stunned. He really didn't expect the fourth prince, who was a combination of various noble habits, would say such words.
Chapter completed!