Roland stood in the backyard of the firing room, waiting for the first batch of cement to come out.
The brick house, which he specially designed for cement production, is about fifteen meters long and four meters wide. There is a door at the front and back, the difference is that the front door is as wide as possible for people to carry materials. The back door was only one person wide, allowing Anna to sneak into the firing room.
To this end, he also built a wall at the half waist of the house to surround the rear half of the firing room. The entrance and exit were guarded by knights - they were all Carter's subordinates, and their loyalty was beyond doubt.
The production process of cement is very simple. The limestone is crushed into powder, mixed with clay and iron powder, the clinker is calcined by dry or wet method, and then ground together with gypsum. The raw materials are very common, and it is difficult to obtain iron powder in large quantities. The key lies in the calcination temperature of the clinker.
Roland couldn't remember the specific temperature required to burn cement, and even if he remembered he couldn't measure and control the temperature—whether it was an infrared thermometer or a thermocouple temperature gun, it was countless times more complicated than cement. He only knew that this temperature is almost similar to the melting point of iron, and the calcination process is also a difficulty in producing cement.
As far as the era of underdeveloped smelting technology is concerned, maintaining the blast furnace temperature has always been a problem that plagues everyone. The heat loss of the ordinary open furnace is very large, and it is difficult to keep the furnace temperature above 1200 degrees. And the reverberatory furnace needs a high temperature resistant liner, and he couldn't figure out how to make refractory bricks for a while. The traditional iron-making blast furnace is even worse. The temperature may be up to the standard, but only relying on the long and narrow furnace cavity to calcine the cement will not be able to burn enough volume after the month of the devil has passed.
Therefore, the firing room designed by Roland did not have any heating measures at all, and he relied on Anna.
The artificially crushed small-grain limestone is mixed with clay and then mixed with water to form a slurry, which is evenly spread in the firing room. Then the knight locked the gate and cleared the handyman. Anna entered through the back door and let the flames bake the slurry on the ground until the iron rods that were put into the room together melted.
Roland was a little restless. This was his first step in guarding Border Town. If cement can't be built, the plan to build a city wall in three months is just empty talk. There is no city wall to block, I am afraid that no one wants to stay in this ghost place. Whether it is real history or fictional literature, a stable base is essential if you want to farm well.
"Your Highness, what you said can really stick stones together?" Carter Lannis, who was standing beside the fourth prince, asked. Although the prince told him that this was the latest research result of the Greycastle Alchemy Workshop, he was still skeptical. After all, those gangsters have 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 collectively known as the art of sages, and are very popular in mainland countries. The royal family generally trains its own alchemists and astrologers, who are used to make secret medicines and predict fate. For ordinary people, these studies are so lofty that they create a mentality of blind faith. Considering this, Roland naturally brought the source of the cement formula to the alchemy workshop. As for whether the chief knight believed it or not, it didn't matter at all.
The flames coming out of the window gradually went out, and it looked like it was done burning.
Roland stood up suddenly, drove Carter out of the yard, and waited alone in front of the back door of the brick house.
The iron door was pushed open with a squeak, and Anna walked out. Roland immediately put the robe over her and brought her a glass of water, "How is it?"
The witch's face was dusty. Although wet cement produced low dust, the hot air during calcination still carried dust. For her who can't wear a mask, it is obviously not very comfortable to stay inside for dozens of minutes. She coughed twice and nodded, "The mud has turned into ashes."
Roland couldn't wait for the temperature in the firing room to drop low enough. He wrapped the wet towel around his head, grabbed the shovel and got into the back door.
The hot air instantly surrounded him, and he felt a little difficult to breathe for a while, and the skin on his hands was roasted and painful. Fortunately, it doesn't take much time to shovel a handful of ash, otherwise staying in this environment for a few minutes may cause high temperature shock.
"Is this what you want?" Anna asked after putting on the witch suit.
"It looks very similar," Roland flattened the powder and felt its residual warmth with his fingers, "I'll have to try it out to find out."
"what's it for?"
"Building houses, building bridges, building roads, there are so many places that can be used. If it can be successful, people's houses will not be afraid of wind and cold in the future, and heavy rain and heavy snow will not be able to destroy them." He patted Xiao Xiao with his other hand. The girl's head, "It was made by you."
Anna bowed her head. I don't know if it was an illusion, but he felt that the girl's breathing became a beat faster.
In theory, the fired clinker is ground with gypsum to adjust its hardening time. But there is no need to think about it so much at this time. Roland took a break and shoveled out two more shovels. Then he called Carter, who was standing outside the courtyard, and asked him to prepare cement mortar according to the ratio of three parts of ash powder and one part of river sand.
The chief knight also doesn't mind doing some rough work. For him, doing this kind of thing is much better than fighting for His Highness or hooking up with a traveling noble lady when he was in Greycastle.
Since no iron powder is added to the raw materials, the color of the prepared cement slurry is light, showing a grayish white color. Roland poured them all on one stone brick, and then buckled the other one. The cement setting time is about four hours. Considering the instability of the trial product, he plans to simply wait until tomorrow to see the results.
The next morning, Roland hurriedly took Carter and Anna to the backyard of the firing room. Pushing the door open, he noticed that the exterior of the cement was in a solidified state and was tightly joined to the two stone bricks. The consolidated surface looked uneven, with hoarfrost in some places.
Roland squatted down, scraped off the hoarfrost produced by the alkalization reaction, and pressed the hardened cement with his fingers. He was delighted by the touch—the cement surface was firm and tactile, which was completely different from the tactile sensation of the soil after tamping it down. Button, also can not leave a trace on it.
After receiving the signal from the fourth prince, Carter first tried to lift the stone bricks, but was unsuccessful. He kicked violently from the side a few times until the junction of the cement and the ground broke, and the two stone bricks were still firmly bonded together. At last he hit them hard with the hilt of his sword, only to knock off a small piece of the edge.
"Is this the effect of 'cement'," Carter realized immediately, "It's incredible. Flowing like a melted candle yesterday, and rock solid after only one night. With this kind of thing, the city walls can be built as fast as they want. With enough stones, we can even build a wall around the border in five years! "
"What's the use of that?" Roland said disapprovingly, "No matter how tall the wall is, it can't stop the enemy from within. I would rather turn the dilapidated wooden houses in Border Town into solid concrete houses, so that my subjects will no longer have to Fear of being homeless after a natural disaster."
"..." The chief knight was stunned, he really did not expect that the fourth prince, who had all kinds of aristocratic bad habits, would say such a thing.
"You will see in the future," Roland reaffirmed the path he was going to take—for many travelers, technology is the primary productive force. And here, the witch is the primary productive force.