Bohemian Cement (2)
"It is an honor to have you back, Your Majesty."
When I arrived at the Sternberg estate with Janos, the first person to greet me was Stefan.
"It has been a while, Stefan. You look remarkably well."
"It is all thanks to the grace you have bestowed upon us, Your Majesty. An old man like me is enjoying such luxury before my time is up."
He was the veteran stonemason who had taken charge of the reconstruction and expansion of Sternberg while I was away. When we first met, he had been nothing more than a pitiful old man, standing in a burnt-out village, lost in despair and worrying about the next day. But things were different now.
He carried the dignity of a construction supervisor who commanded over ten thousand laborers and technicians, building a massive industrial city from the ground up.
The Sternberg I found after so long smelled entirely different from Prague. The acrid scent of sulfur dug deep into my lungs, and the heavy smoke exhaled by burning coal hung in the air. It was the exact opposite of the sweet, apple-scented breeze of Prague, yet to me, it smelled far more fragrant. This was the scent of civilization progressing and evolving.
"How is the status of the city?"
"There is much to report, but first, I shall address the concerns you raised in your letter," Stefan said confidently.
"I have heard well of the trouble Prague is facing due to the soap bubbles. But this place is different."
"You seem confident."
"I have every reason to be. Did you not order the water and sewage systems to be thoroughly installed from the moment you drafted the city plan? We laid the pipes beneath the roads in advance and designed the sewage to be collected separately in septic tanks. I have reinforced everything meticulously so that it would hold firm even if the population were to double."
I was satisfied. Indeed, it was far easier to paint on a blank canvas than to paint over a ruined one. If Prague was a relic of the old era that needed to be overcome, Sternberg was the prototype of the 21st-century city I had designed.
"Excellent. And the progress of the city construction?"
At my question, Stefan pointed toward the construction site.
"The manpower you sent is so vast that we have more hands than we know what to do with. As you can see, we have finished the foundation work for the residential zones by dividing them into the grid patterns you instructed. The supply of coal from Silesia is also smooth, so we have no worries about fuel for the kilns."
He paused for a moment, then took off his hat and scratched his head. A look of distress clouded his face.
"However... there is just one problem."
"A problem?"
"Yes. We have enough manpower and fuel, but the speed at which the buildings are rising simply cannot keep up."
Stefan pointed to the half-finished red brick buildings.
"Mixing the clay, putting it into molds, drying it in the shade, firing it in the kiln, and letting it cool... this process alone takes over a full week. We are running the kilns 24 hours a day without rest, but the amount of bricks produced in a day is barely enough to build a few houses."
"Hmm..."
The problem Stefan pointed out was the limitation of traditional masonry construction. Bricks were excellent materials, but mass production required an absolute amount of physical time. No matter how much high-calorie coal from Silesia we poured in, we could not artificially shorten the chemical time required for the earth to be fired and transformed into ceramic.
"Migrants from Prague keep arriving, and we need to build houses for them to stay in and expand the factories... but because there are no bricks, the number of days the laborers spend just twiddling their thumbs is increasing."
Stefan let out a deep, frustrated sigh.
"Starting tomorrow, we will have to stop construction and wait until the bricks are fired. The wages for the idle laborers are not insignificant, and... I am ashamed, Your Majesty, as you trusted me with this task."
He bowed his head, blaming his own incompetence. I patted his shoulder silently.
"Raise your head, Stefan. It is not your fault."
"But..."
"You did your best. I know well that this is the limit of the method of firing earth to make stone."
I looked out at the construction site. The idle cranes, the half-built red brick houses, and the laborers gathered in small groups, chatting because they had nothing to do. If I could not solve this bottleneck, the expansion of Sternberg would stop here. The sewage project in Prague would also be impossible, no matter what.
But I already had the answer to this problem.
"Let us go to the steel mill."
I led Stefan across the square toward the Royal Steel Mill. As we drew closer, the acrid smell of coal and the metallic scent that stung the nostrils grew stronger. Upon entering the steel mill, a sweltering heat washed over our faces. In that heat, a man covered in soot and drenched in sweat greeted us. It was Tomas, the blacksmith of Sternberg and the technical officer currently in charge of the blast furnace.
"I have been waiting, Your Majesty."
Tomas had already received my letter and was fully prepared. In a corner of the workshop behind him, a strange sight unfolded. In the place where molten iron or steel ingots should have been piled, there were mountains of unidentified gray and white powder. Beside them, fine sand, gravel, and buckets of water from the river were lined up.
Stefan pointed to the piles with a puzzled expression.
"Your Majesty, what is all this? It does not look like flour..."
"It is similar. The only difference is that instead of baking bread, we are baking a city."
I chuckled and grabbed a handful of the gray powder. The fine particles flowed smoothly between my fingers.
"Stefan, as a stonemason, you must have heard of the architecture of Rome."
"Of course. You mean the legendary buildings like the Pantheon or the Colosseum, right? They are such marvelous legacies that rumors circulate among stonemasons that they were built by gods."
Awe filled Stefan's eyes. The Roman ruins, which had stood for over a thousand years, were an unattainable ideal and an unknown realm for medieval craftsmen.
"What do you think is the secret to those buildings lasting a thousand years?"
"Well... is it not because the stonemasonry skills of the ancients were far superior to ours? Perhaps the technique of fitting stone to stone without a gap..."
I shook my head firmly.
"No. The Romans did not carve stone."
"Pardon...? They did not carve stone?"
Stefan's eyes widened. To him, who had spent his entire life splitting stone with a chisel, it was a concept he could not even imagine.
"*Opus Caementicium*. The Romans built frames and poured the mixture inside. The mixture, which flowed like water, turned into rock harder than natural stone over time. That is the secret to how Rome built a thousand-year empire."
I pointed to the materials Tomas had prepared.
"The core ingredient that made that miracle possible was the red volcanic ash spewed from Mount Vesuvius near Naples. The Romans called it *Pozzolana*."
Volcanic ash. It was a trace of the earth's fury, but at the same time, it was the adhesive that supported civilization. The silica and alumina components abundant in volcanic ash—when these met lime and water, they triggered a violent chemical reaction, transforming calcium hydroxide into calcium silicate hydrate.
Because this compound possessed powerful hydraulic properties that hardened like stone even underwater, the Romans used this principle to build ports in the middle of the sea and raise massive domes. However, when the empire fell and the Mediterranean trade routes were severed, this great technology also vanished into the annals of history.
Medieval craftsmen, unable to obtain the core ingredient, Pozzolana, were at a loss. Lime mortar without volcanic ash was nothing more than mud that melted away whenever it rained. In the end, they dismissed Roman architecture as the magic of the ancients and regressed to a primitive era of picking up chisels and hammers to carve stone again.
It would be hundreds of years later, in the 19th century, that this lost technology would reappear in the world through an Englishman.
At that moment, Janos, who had been listening from the side, tilted his head and asked.
"I am always in awe of your vast knowledge, my lord, but this is Bohemia. There is not a single volcano nearby, let alone Naples. Where on earth do you intend to find volcanic ash?"
"If there is no volcano, I can simply make one."
"M-make a volcano?"
I gestured with my chin toward the blast furnace roaring with a thunderous sound in the back.
Kwoooooo—!
The massive blast furnace, greedily spitting out red flames. That thing, which melted iron ore to draw out molten iron, was nothing less than an artificial volcano crafted by human hands.
"Tomas, explain."
"Yes, Your Majesty."
Tomas stepped forward and opened a sack full of gray powder.
"This is slag. It is the waste that floats on top when melting iron in the blast furnace. In the past, it was treated as trash to be dumped in the river, but..."
Tomas grabbed a handful of the powder and held it out in front of Stefan's eyes.
"However, following your orders, I rapidly cooled the boiling slag in cold water. It became sand that shattered like glass. This powder is what we made by grinding that finely."
"Slag... you mean waste?"
Stefan fiddled with the gray powder with an incredulous expression.
"Your Majesty, are you truly saying this waste is the same as Roman volcanic ash?"
"Chemically, it is almost identical. No, it might even be superior to natural volcanic ash since the impurities are controlled."
Blast furnace slag is densely packed with silica, alumina, and calcium oxide. When this is rapidly cooled, it becomes a glassy state that has not crystallized; when it meets lime and water, the latent hydraulic properties explode into life. That was the identity of 'blast furnace slag cement,' the backbone of modern architecture.
"Seeing is better than hearing a hundred times. Tomas, begin the mixing."
At my instruction, Tomas and his assistants began to move in perfect order. They poured the gray slag powder and white quicklime powder into a large wooden barrel. The ratio was the optimal mixture I had calculated in advance.
Swish-
The whitish powders mixed together, and thick dust rose within the workshop.
"Now, pour the water."
At my command, Tomas tilted a large bucket of water.
Hissssss—!
Rough steam surged upward. It was because of the intense heat of hydration emitted as the quicklime met the water and transformed into calcium hydroxide. The mixture in the barrel bubbled and boiled like a living creature, exhaling white steam.
Janos, who was watching from nearby, jumped back in surprise.
"Wait, you poured water on stone powder and it generated heat? What kind of bizarre magic is this?"
"Think of it not as magic, but as the labor pains of becoming stone."
I replied, staring calmly at the rising heat. The assistants hung a large wooden spatula and stirred the mixture. As the powder and water clung together, the mixture gradually turned into a thick, dark gray mud.
"Now, add the sand and gravel."
River sand and finely crushed gravel were poured in.
Squish, squish-
Thick beads of sweat formed on the foreheads of the assistants stirring the heavy, sunken mixture. Stefan was still watching the scene with eyes full of doubt.
"Your Majesty... I apologize, but are you truly saying that sludge will turn into stone? To my eyes, it looks like nothing more than muddy water that will be washed away by a single rain."
"It may look that way now. But it will be different by tomorrow morning."
I pointed to the wooden frames I had prepared in advance.
"Pour it."
Tomas and his assistants groaned as they lifted the wooden barrel.
Rumble—! Splat!
The gray, monstrous substance poured into the wooden frame. It was a fluid substance with no form and no fixed shape. However, this flexibility was the true value of this material. Depending on the shape of the frame, it could become a square brick, a magnificent pillar, or a road spanning the entire city.
As we smoothed the surface of the mixture filling the frame, a fairly decent plane appeared. I took off my glove and placed my palm lightly on the mixture, which had not yet hardened. It was warm. The subtle heat generated by the chemical reaction was transmitted through my palm.
"Stefan."
"Yes, Your Majesty."
"When the sun rises tomorrow morning, bring the heaviest hammer you have and strike this."
I said, wiping the gray mixture off my hand.
"It may look like worthless mud now, but by tomorrow, you will throw away your chisel and hammer. From now on, just by building frames and pouring this gray water, you will be able to build city walls that would have taken ten years to stack in just one month."
Stefan swallowed hard and stared at the gray pool inside the frame. In his old eyes, a faint expectation for a new era was crossing with the fear of his lifelong common sense as a stonemason crumbling down.
Janos approached my side and whispered quietly.
"My lord, if that truly hardens... the Prague sewage project will be the least of our worries."
The sharp-witted fellow. He seemed to have already grasped the military value of this technology.
"City walls, fortresses, roads... the very aspect of war will change completely."
"Indeed. Now, we can erect city walls in a heartbeat before the enemy even makes their ladders."
Now, it was a time of waiting. The time for the hydration reaction to end and for the crystals to entangle and bond with each other. And once that time passed, Bohemia would break the shell of the Middle Ages and finally cross the threshold of the modern era.
"Well, let us withdraw for today. We gather again tomorrow morning."
I turned around and added to Tomas.
"Oh, Tomas. Keep collecting the slag. We will need mountains of it in the future."
"As you command. But, Your Majesty..."
Tomas asked, hesitating.
"What should we call this new stone? My tongue gets twisted trying to call it *Opus*... whatever."
I paused for a moment and pondered. In the distant future, the 19th-century Englishman Joseph Aspdin would restore the lost technology of Rome and patent it. He named it 'Portland Cement' because the hardened result resembled the limestone of the Isle of Portland in England.
'But I have no reason to borrow the name of an English island.'
This gray powder would be born in the blast furnace of Sternberg, cover the roads of Prague, and eventually become the material that would build every wall in Bohemia. If so, the name, too, should go to a master worthy of it.
I curled up the corners of my mouth and answered shortly and firmly.
"Bohemian Cement. From now on, call this stone by that name."