Firing the Cement

Roland stood by the kiln, waiting for the first batch of cement.

The brick structure was designed for cement production, about 15 meters long and four meters wide. It had a front and a back door. The front door was designed wide enough to allow the transport of materials and people coming in and out of the room. The back door, on the other hand, was only large enough for one person and functioned as Anna's secret entrance.

To this end, he also built a wall surrounding half of the kiln and stationed guards at the entrance and exit. They were all Carter's men and he had no doubt about their loyalty.

The cement production process was easy to explain. First, limestone was crushed into powder, and then mixed with clay or iron powder. It would result in a paste whether they use the wet or dry method. After combining it with gypsum, the cement would be ready for use. Raw materials were readily available and no iron powder was included for it was difficult to produce. The key was in the calcination temperature.

Roland could not remember the specific temperature required to melt the cement. Thanks to the fact that he did not have the necessary tools like an infrared thermometer or a thermo coupling temperature gun needed to measure the said temperature, the process was made incredibly difficult. He only knew that the melting point of cement was similar to that of iron, and that the calcination process was also a tricky factor when it came to making cement.

For such an era of undeveloped technology, it was a huge problem to simply maintain the temperature of the blast furnace. The common open furnace would result in great heat loss and it was difficult to keep it burning above 1,200 ℃. As for the reverberation furnace, it required an inner capable of sustaining higher temperatures, but he did not know how to create the refractory bricks. The traditional blast furnace used for iron was even worse. The temperature may suffice, with only a narrow furnace cavity available to calcite the cement, but they could not produce enough cement before the end of Months of Demons.

With this in mind, Roland designed a kiln that needed no heating and relied on Anna instead.

Broken particles of limestone and clay were mixed with water to form a paste, which was spread evenly throughout the firing room. Then the knights locked the door and cleared out the laborers. Anna then entered through the back door and heated the ground beneath the paste until the iron bar placed inside the room also melted.

Roland was becoming restless. This was his first step in guarding Border Town. If he could not produce any cement, his plan of building a city wall in three months would just be empty words. Without a wall to protect the town, he worried that no one would be willing to stay in this godforsaken place. Whether in history or fictional literature, a stable base was necessary for agriculture.

"Your Highness, you're saying that this material can hold stones together?" asked Carter Lannis, who stood near Prince Roland. Even though the prince had said this was the result of the latest research by the alchemical workshop in Kingdom of Graycastle, he was nonetheless skeptical. After all, that group of people was never famous for being useful.

"Who knows? That's what they said," Roland replied.

In this world, alchemy and astrology were known as the sage arts, and were very popular in the mainland. The royal family would generally keep their own alchemists and astrologers to predict and improve their fate. For ordinary folks however, such knowledge was beyond their comprehension and thus had little enthusiasm for them. Keeping this in mind, it was only natural for Roland to claim that the cement was a product of the alchemical workshop. He did not care about whether the chief knight believed it or not.

The flame in the window eventually died down. The firing of the cement seemed to be complete.

Roland stood up at once. Sending Carter away to the yard, he waited alone in front of the brick house.

The iron door creaked as it opened and Anna stepped out, naked. Roland draped a robe over her at once and handed her a glass of water. "How was it?"

The witch's face was painted a dusty gray. Even though wet cement would not produce much dust, it would still appear when the cement was burning. Since she could not wear a mask, it was uncomfortable for her to stay inside for tens of minutes. She coughed twice and nodded. "The mud has turned gray."

Roland was too impatient to wait for the temperature to be lowered. Wetting a towel, he wrapped it around his head and grabbed a shovel. He then went in through the back door.

Hot air instantly engulfed him and he found it difficult to breathe. The skin on his hands was burnt raw. Fortunately, shoveling the ashes took only a short moment. Otherwise, he might really experience thermal shock had he stayed any longer.

"Is this what you want?" Anna asked, staring at the material. She had already put on her witch's robes.

"Looks like it." Roland flattened the powder and tested the temperature with his fingers. "I wouldn't know for sure until we use it."

"What's the use of this thing?"

"To build houses and bridges and to repair roads. There are too many uses for this thing. If it succeeds, people won't have to worry about the cold or the rain and snow damaging their houses." Using his other hand, he patted the girl on the head. "It's all thanks to you."

Anna lowered her head. He wasn't sure if it was just an illusion, but the girl's breathing seemed to have sped up a notch.

In theory, the fired material should be grinded with gypsum as to adjust its hardening time. But there was no need to think about so much right now. After a short break ,Roland picked up two shovels and called for Carter, who was standing outside the courtyard. Roland told him to mix the gray ash proportionally with the river sand in a ratio of 3 to 1 to prepare cement mortar.

The chief knight did not mind doing menial work. In his opinion, it was much better than fighting or chasing after the noble ladies for His Highness in the Kingdom of Graycastle.

As there was no iron powder in the raw mixture, the resulting paste looked off-white. Roland piled the paste on a brick and placed another brick on top of it. It would usually take around four hours for the cement to become solid. As this was merely a trial run, he decided that it would be best to wait until tomorrow to test the mixture.

The next morning, Roland hurried to the kiln room, bringing Carter and Anna with him. When he opened the door, he noticed that the cement appeared solid and the bricks seemed to have stuck together. The surface of the material seemed rugged and part of it was covered in white frost.

Roland squatted down. It was natural for the alkalization process to result in some white frost. He pressed onto the hardened cement and his heart leaped. The cement was rock solid, completely different from the texture of the solid clay. Even when he pushed into the cement firmly, there was no mark on its surface.

After getting the signal from Prince Roland, Carter first tried to lift the bricks. He then attempted to kick the bricks until they gave way. The cement dislodged from the ground, yet the bricks remained stuck firmly together. He ended up using the hilt of his sword to knock them apart, but he succeeded in only knocking off a small corner of the bricks.

"So this is the effect of the so-called cement." The purpose of the material dawned on Carter. "It's simply incredible. It flowed like wax from a melting candle yesterday, but in just one night it had become as strong as a rock. With this, we can build the wall as fast as we want. As long as we have enough bricks, we could even build a wall around Border Town in less than five years!"

"What's the use of that?" Roland asked. "A tall wall would not be able to stop enemies from within. I'd rather turn the old wooden huts in Border Town into solid cement houses, so my subjects would no longer have to worry about losing their homes in natural disasters."

"..." The chief knight was stunned. He did not expect Prince Roland, who was known for his many aristocratic vices, would suggest such a thing.

"You'll understand it in the future." Roland reaffirmed the path he was taking. For many people who travelled through time, technology was the gate leading to productivity. But here, the witches were their path to the future.