Cement

Cement is a newly introduced building material in the world. Roland uses it to built Border Town's first defensive great wall in less than 3 months as well as renovate entire residential districts.

## Production

Due to lack of technology Roland decided to use Anna's magic power to sustain constant temperature at iron melting point. For this purpose he built brick house 15 m long and 4 m wide with two doors on opposite sides. From one side workers brought raw materials, while from other Anna entered the room. To obtain cement Roland mixed limestone powder and clay powder with water and spread paste evenly on the floor, then Anna heated the ground under paste until iron bar was melted. The resulting gray ash was mixed with river sand in ration 3:1 to get cement mortar.

## Construction project: Great Wall

*See also: Chapter 12 (novel)*
First project was the great wall from Redwater river to North Slope Mountain Ridge to defend against the demonic beast invasions.

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.

## Use of Cement

"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.

## Synthesizing cement: alkanization

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."