The scorching flames from the burning coal emitted a soaring heatwave that distorted the surrounding air.
Even from a dozen meters away, one could feel the searing temperature.
Soon, the limestone thrown in was burned glowing red by the coal.
This coal was high-quality anthracite with a very high carbonization level.
If Wu Liang had used such high-grade material to burn lime in his previous life, he would have been lambasted for running a losing business, if not outright cursed to death.
But things were different here; Black Wind Valley was full of anthracite.
Even if he wanted to find bituminous coal, he couldn't; the resources here were simply too abundant.
Moreover, normally anthracite is buried deep underground; finding it exposed on the surface is extremely rare.
Regarding this, Wu Liang speculated that some violent geological evolution must have occurred in this place, thrusting the deep coal mines upward.
However, that wasn't important; if it hadn't been exposed, Wu Liang wouldn't have discovered it.
As long as it was available for use, he didn't care where it came from.
"It's amazing! Lord Wu Liang, this coal is truly good stuff—much better than the charcoal we burn!"
Standing beside the lime kiln, Chief Steward Wula felt the irresistible high temperature, her eyes shining uncontrollably.
"Of course. The maximum temperature of charcoal is only 600-1200 degrees Celsius, while this coal can reach high temperatures of 1000-1700 degrees with full combustion and a bellows."
Wu Liang smiled slightly upon hearing this and explained patiently.
"Celsius? What is that?"
Wula looked completely bewildered.
"Celsius is... never mind. Just produce it according to my instructions; I will slowly teach you this knowledge later."
Wu Liang sighed, too lazy to explain further.
He had almost forgotten that these Tribe members were practically a cultural desert; it was impossible for them to understand the cultural knowledge of Earth.
"It seems that cultural literacy work really needs to be put on the agenda."
"At the very least... start with the nine-year compulsory education curriculum."
Watching the flames of the lime kiln, Wu Liang had a new plan in mind.
After all, right now it was just burning lime and smithing iron at most, which only required accumulated experience and pondering; anyone with a bit of talent could do it well quickly.
But if they lacked a cultural foundation, when the industrial technology tree developed to higher levels later, being illiterate would mean they couldn't even handle blueprints or numbers, which would severely impact development efficiency.
The lime kiln burned for a full day and night.
On the morning of the second day.
The old Artisan Wula was leading a group of people, waiting in front of the extinguished and cooled lime kiln, her face full of anticipation and nervousness.
"Lord Wu Liang!"
Seeing Wu Liang approach, Wula hurried forward to greet him.
"Lord Wu Liang, this first kiln has burned for a full day and night according to your orders. It has cooled down now, just waiting for you to open it!"
"Good job."
Wu Liang nodded with satisfaction.
He walked to the lime kiln and reached out to touch the kiln wall; only a hint of warmth remained.
"Open the kiln," Wu Liang ordered.
"Yes!"
Wula responded.
She immediately directed several brawny female Artisans to use iron picks and hammers to start knocking open the pre-set discharge port.
"Clang! Clang!"
The stones and earth sealing the opening were pried away one by one.
As the last stone was moved, a gust of hot white dust rushed out.
Everyone subconsciously took a few steps back, covering their noses and mouths.
Inside the discharge port, a pile of grayish-white lumps rolled out.
They were no longer the bluish-gray stones that had been put in earlier; instead, they had become porous and whitish, looking as if they would crumble at a touch.
"This... this is what was burned?"
Wula's eyes widened in confusion.
"It doesn't seem... like anything special?"
"Don't be in a hurry; this is only the first step."
Wu Liang smiled. Under his direction, the Artisans transported these hot quicklime lumps to a large pit dug nearby and began to slowly pour water over them.
"Sizzle—"
The moment the water touched the stones, a violent sound suddenly erupted!
A large amount of white steam instantly rose from the pit, accompanied by a crackling sound of bursting.
The previously quiet pile of stones tumbled violently, expanding and shattering, finally turning into a pile of hot white powder.
Accompanied by a startling heatwave, the surrounding people all retreated several steps again.
"Oh my god!"
"These stones... are alive?"
"The stones are actually moving! What's happening?"
The Artisans and the surrounding warriors were all scared witless.
One by one, they stood dumbfounded, watching this incredible scene before them.
Wu Liang signaled for everyone not to panic and explained loudly:
"This kind of bluish-gray stone is called limestone. After being calcined at high temperatures by coal, it turns into this substance, which I call quicklime."
"And when this quicklime meets water, it undergoes a violent reaction, releasing a large amount of heat and turning into this white powder."
"This powder is called slaked lime."
Wu Liang tried his best to explain in a way that Wula and the others could understand.
Expecting them to understand the chemical principles behind it would have to wait until after the basic literacy work and nine-year compulsory education were established.
The crowd seemed to understand somewhat, and they all quieted down, no longer afraid.
When the limestone reaction gradually subsided, it had completely turned into a pile of fine white powder, with faint wisps of steam rising from it.
Wu Liang did not stop; he directed the workers to bring over the clay and river sand they had dug up.
"According to the ratio I told you: one part slaked lime, two parts river sand, and three parts clay. Add water and stir it evenly for me!"
Wu Liang gave the order.
Dozens of Tribe members immediately got to work, using wooden shovels to stir vigorously in a huge pit.
Soon, a pit of gray, sticky-looking slurry appeared before everyone.
"Lord, this... what is this again?"
Wula looked at this pile of mud-like substance, even more confused.
Was Lord Wu Liang teaching them to play with mud?
"I call it cement," Wu Liang said, as he had an Artisan bring over two medium-sized stones.
He personally used a wooden shovel to smear the cement slurry onto the cross-section of one stone, then pressed the other stone on top of it. The gray slurry was squeezed out from the gaps.
After doing this, Wu Liang directed the Artisans to use this slurry to build a waist-high low wall nearby.
Finally, using prepared wooden boards to form a frame, he poured all the remaining cement slurry inside and smoothed it out.
"Alright, now all we have to do is wait for it to dry. This low wall will be bonded together, so strong that it cannot be pushed over."
The next morning, Wu Liang led everyone back to the low wall from yesterday.
After a night of air-drying, the cement at all the joints had turned into a hard grayish-white.
"Wula, come and try to move the stones on top," Wu Liang said to the old Artisan.
"Yes, Lord."
Wula stepped forward, took a deep breath, and used all her strength to try and move the two stones on the low wall.
However, the two stones seemed to have grown together, remaining perfectly still.
"Let me!"
A burly female Artisan stepped forward.
"Heave!"
She hugged the stone and let out a roar, the muscles on her arms bulging and veins popping.
Under everyone's tense gaze, the stones on the low wall did not budge in the slightest.
Wu Liang then had someone bring a hammer to strike it. Besides leaving a few white marks, the wall couldn't be broken at all.
"It really stuck!"
"Incredible! It's like it has become one single giant rock!"
Exclamations erupted from the crowd.
"Not bad. This is the magic of cement. Everyone, follow the method I taught you and increase production!"
Wu Liang issued orders to the crowd.
"Yes!"
The success of the cement was like a wildfire, instantly igniting the enthusiasm of the entire Black Rock Tribe.
In the following days, a large construction site was opened up on the outskirts of Black Wind Valley.
The original wasteland was leveled, and over thirty lime kilns rose from the ground, lined up in a neat row.
From a distance, they looked like a group of silent giants exhaling massive heatwaves, exuding a rugged industrial aura.
The air in the entire Black Wind Valley was filled with the unique smell of burning coal and a faint scent of lime.
Wu Liang couldn't help but feel emotional as he watched all this. With these foundations, the construction of the Black Rock Tribe would see a qualitative leap.
"Fortunately, there is no Environmental Protection Bureau in this world..."
[Ding! Detected that the Host has successfully developed the cross-era building material 'cement', greatly advancing the progress of civilization!]
[Ding! industrial technology tree module upgraded! Unlocked the 'Civil Engineering' branch!]
[Ding! Congratulations to the Host for receiving the reward: Civil Engineering Basic Theory Knowledge Pack!]
A series of system prompts rang out in Wu Liang's mind, and the smile on his face deepened.