Three Kingdoms: A Million Soldiers Grown from the Fields

Chapter 128 Foundation Building (Bonus Chapter Due to My Adorable Little Daughter!)

The side room in the backyard of Zhang Xian's residence had its doors and windows tightly closed, isolating it from the noise and commotion of the outside world.

A peculiar smell permeated the air: the pungent astringency of quicklime, the alkaline odor of wood ash, the earthy smell of freshly dug clay, and a faint, almost imperceptible, burnt smell.

This place has become Zhang Xian's secret workshop.

In the corner were a few inconspicuous items: a few pieces of gray and white limestone, a basket of finely sifted river sand, several bags of clay of varying shades, and a small pile of dark iron slag from the blacksmith's shop.

In the very center, a large, roughly 2.5-meter-tall earthenware vat was filled with clear water, on the surface of which floated several pieces of quicklime that were reacting violently, emitting fine bubbles and radiating scorching heat.

This is the first step in cement manufacturing: preparing slaked lime.

Yes, Zhang Xian has been spending these days theoretically experimenting with these things, cement, and mortar.

The main purpose of getting cement was also for his grassland strategy.

If one wants to sweep across the grasslands and conquer the nomadic tribes of the Hu, Xianbei, and other ethnic groups, then transit is of paramount importance.

Unlike the inland areas, the grasslands have different environmental markers to help with navigation. The vastness of the grasslands is no exaggeration. He took some time to visit the grasslands on the outskirts of Bingzhou, and all he could see was the same scenery.

If you haven't lived on the grasslands since childhood, getting lost after entering the desert grasslands is an inevitable outcome.

After all, not everyone has Huo Qubing's terrifying sense of direction, which is like having a satellite navigation system.

You agree, General Li Guang.

Therefore, to control the grasslands, it is necessary to build cities with auxiliary directional identification to help generals determine their location and provide supplies.

In fact, the Western Han Dynasty had already attempted to build cities on the grasslands, and even actually established several surrender cities to consolidate its rule over the surrounding grasslands.

But in the end, they gave up because timber was scarce on the grasslands, and all building materials could only be transported from the border regions.

Furthermore, after Zhao Xin, a general who accepted the surrender of the Xiongnu, burned down a surrender city, the matter of building a city on the grassland was abandoned.

Therefore, Zhang Xian planned to produce cement and use its convenience to repair facilities. Even if he couldn't build a magnificent city, as long as he could pile up a cement brick wall even one meter high, he could completely control a part of the area around the city.

As long as there are city walls, the fighting power of the Xiongnu and other nomadic peoples can be reduced by 80%. Having a city is like laying a tortoise shell on the grassland. Even with the Xiongnu, other nomadic peoples and Xianbei peoples' ability to attack fortified positions, they can only look on with fear.

This is why when nomadic tribes from the grasslands migrated south to raid for resources, they would only plunder the wealth and people outside the city without causing much damage to the city itself.

Zhang Xian, with his sleeves rolled up and fine beads of sweat on his forehead, was carefully stirring the scalding, murky liquid in the vat with a long wooden stick.

The pungent smell made him frown slightly, but his eyes were focused and sharp. Quicklime is the basic binder, but pure lime mortar is easy to soften when it comes into contact with water, and it is not strong enough and not durable.

What he needs is something stronger, faster, and more water-resistant.

"My lord, the 'gray stone' and 'clay' you requested have been prepared. As you instructed, they have been smashed into fist-sized pieces."

Han Ji pushed open the door and coughed from the stench inside. Looking at the bubbling white liquid in the vat, his eyes were full of doubt: "Is my lord mixing mortar?"

He loved craftsmanship, so it wasn't hard for him to tell what his lord was doing.

"Your arrival is just in time."

Zhang Xian put down the wooden stick and pointed to a pile of quicklime slurry that had settled and turned into a fine paste beside the vat.

"This is the foundation, but it's not enough. I want to create something stronger, something that... can solidify quickly, is as hard as stone, and is not afraid of water or fire."

Han Ji's eyes widened: "Such a thing exists in this world?"

"We'll only know after we try," Zhang Xian said confidently.

He picked up a piece of limestone and a piece of dark clay: "The key is the temperature and the ratio. Gongzhi, help me find someone to build a kiln, the kind of vertical kiln that can fire bricks and tiles. It doesn't matter if it's small, it's just an experiment right now."

During this period, Han Ji was busy with spring plowing and land reclamation, so Zhang Xian didn't bother him too much. Now that spring planting is almost over and land reclamation is on track, he can finally allocate manpower to conduct hands-on experiments on cement.

Han Ji nodded in agreement upon hearing this.

A few days later, in a secluded corner west of Luqi City, a simple vertical kiln rose from the ground.

The kiln opening is not large, but the kiln chamber is quite deep and is made of refractory clay bricks.

Zhang Xian personally directed several trustworthy craftsmen, carefully selected after thorough background checks, to begin cement production.

He had people carefully select limestone fragments, clay fragments, and a small amount of finely ground iron slag, mixed in different proportions, and divide them into several small piles, each marked separately.

“First kiln, pure limestone powder.” Zhang Xian pointed to the pile of material marked “A”.

"The second kiln yielded 70% limestone and 30% black clay." (Standard B)

"The third kiln yielded 60% limestone and 40% black clay." (Standard C)

"The fourth kiln: 60% limestone, 35% black mud, plus half a pound of black slag powder from this blacksmith's shop." (Biao Ding)

"Fifth kiln: 50% limestone, 45% black mud, and 0.5% black slag." (Standard E)

The craftsmen looked at each other, bewildered. Burning stone? And mixing it with mud and iron slag? What could possibly be produced?
But no one dared to question it. They silently mixed the materials in different proportions and sent them into the kiln chamber, stacking them neatly layer by layer.

"Start the fire! Blow the air out!" Zhang Xian ordered.

Flames rose from the kiln opening, and the bellows made a dull "whoosh" sound as the craftsmen stomped on them, pushing the flames deeper into the kiln chamber with powerful airflow.

Zhang Xian stared intently at the color of the flames at the kiln opening, silently counting the temperatures in his mind: orange-red 800°C... bright yellow 1000°C... close to incandescence 1300°C!

These are all experiences he gained from working with steel furnaces, combined with his craftsmanship skills. He has long been an expert in temperature reading.

He needs to reach and maintain high temperatures sufficient to decompose limestone and allow it to undergo a solid-phase reaction with the silica and alumina components in clay, producing cement minerals such as calcium silicate and calcium aluminate!

"Maintain firepower! The blowers must not be stopped!" Zhang Xian's voice involuntarily carried the authority of a superior, his eyes fixed on the flames at the kiln opening.

Sweat streamed down his temples, but he was oblivious, his entire focus on the blazing flames of the kiln.

This is the most critical calcination stage, where temperature and time determine whether enough active minerals can be generated.

He ordered his men to bring several pre-prepared, unglazed ceramic blanks and place them at different distances from the kiln opening to observe their degree of sintering and softening, thereby indirectly determining the temperature zone inside the kiln. This was the most primitive thermometer he could think of.

Of course, this was not for his use, but rather to guide craftsmen in recognizing temperature.

Several hours later, the kiln fire gradually died down.

Zhang Xian ordered all kiln doors and flues to be sealed to allow the kiln to cool slowly.

This "smothering" process is equally important; slow cooling helps to form a stable mineral crystal structure.

Another day and night passed, and the kiln temperature dropped to a manageable level. Zhang Xian personally led the craftsmen to carefully open the kiln door. A wave of heat mixed with dust rushed out. Inside the kiln, the material blocks in different areas exhibited different states.

The pure limestone marked "A" has mostly decomposed into loose quicklime powder, which crumbles at the slightest touch.

The main reason for burning pure limestone was to determine how many impurities were in the limestone in this area. After burning it this time, he was able to determine the purity of the limestone in this area.

The two markings, “B” and “C”, indicate that the mixture of limestone and clay was sintered into hard blocks of varying shades of color, but the structure was uneven; some parts were as hard as stone, while others were brittle and easily broken.

The two markings, “D” and “E”, especially “E” which contains iron slag, result in a darker, almost grayish-green color in the sintered block. The texture appears more uniform and dense, and it produces a crisp sound similar to ceramic when struck!
A hint of joy flashed in Zhang Xian's eyes.

He personally and carefully chipped off several pieces of sintered material from the "E" zone with a hammer, placed them in a stone mortar, added a small amount of water, and vigorously ground them. The hard sintered blocks gradually crumbled under his heavy blows, eventually being ground into a fine grayish-green powder.

"Fetch water! And clean river sand!" His voice carried a hint of excitement.

The craftsmen immediately brought over clean water and a basin of fine sand that had been sifted and washed.

He took a flat stone slab, mixed the ground grayish-green powder with sand in a ratio of about three parts powder to one part sand, then slowly added water and stirred it quickly with a wooden chip.

The grayish-green powder reacts rapidly with water! The mixture thickens and solidifies at a visible rate, emitting a slight heat.

He immediately scraped the viscous paste onto the stone slab and smoothed it out.

"Quickly! Grind the powders of the other formulas into a fine powder as well, mix them with sand and water, and spread them on the side for comparison!" he instructed.

The craftsmen immediately sprang into action.

Soon, several mortar test blocks appeared side by side on the stone slab, pure lime mortar (marked A).

Lime-clay sintered powder mortar with different proportions (B, C, D)

And the gray-green powder mortar (E) personally handled by Zhang Xian.

Time passed little by little.

The surface of pure lime mortar (A) gradually turns white and dries, but when pressed with a finger, it can still leave obvious dents.

Mortars B, C, and D harden slightly faster and have slightly improved strength, but the difference is not significant.

Only the No. E gray-green mortar, with the darkest color, hardened significantly faster than the others! In less than an hour, the surface had become quite hard, and it was difficult to leave a mark even when pressed firmly with a finger!
Zhang Xianqiang suppressed his excitement and waited another day.

The next morning, he came to the stone slab again.

The surface of test block E was completely dry, exhibiting a deep, uniform bluish-gray color. It was hard and produced a crisp sound when struck. He gently tapped the edge with a small hammer; the block broke easily, but the fracture surface was dense, with tightly bound particles, far superior to the other loose and brittle mortars.

"Bring water and soak them!" he ordered.

Several test pieces were placed into ceramic basins filled with water.

Soon after pure lime mortar (A) was immersed in water, its edges began to soften and disintegrate.

After soaking for half a day, mortars B, C, and D also showed obvious signs of softening.

Only the No. E gray-green mortar test block, after being soaked in water for a whole day and then wiped dry, remained as hard as ever! Scratching it with a knife left only faint white marks!
"It's done!" Zhang Xian looked at the most primitive cement mortar test block, which was created at the end of the Eastern Han Dynasty, in his hand, and breathed a long sigh of relief, feeling a huge sense of accomplishment.

Although limited by the purity of raw materials and calcination process, its strength and setting speed are far inferior to modern cement, but it does possess the key characteristic of hydraulic cementitious materials: it can harden in water and maintain its strength! This surpasses most adhesive hardeners commonly used at the time!

Of course, it can't compare to the special formulas kept by some imperial courts, but those adhesive and hardening formulas also lack the economic universality that cement possesses.

"This thing...this thing is miraculous!" Han Ji, who had been watching from the sidelines, witnessed the whole process, especially the miraculous scene of it not dissolving in water. He was stunned and carefully picked up a piece of test block number E.

Feeling the heavy, hard texture, his voice was filled with excitement, as if he had learned a new skill.

"My lord, this...this gray powder, is this the 'cement' you mentioned?"

"It's a prototype; it still needs improvement before it's truly usable," Zhang Xian said calmly.

"The calcination temperature, raw material ratio, especially the proportion and fineness of iron slag, still need to be repeatedly tested and optimized. The grinding also needs to be finer, and it would be best to find a water mill or stone mill."

He pointed to the No. E material area: "This proportion is correct. The limestone is about 50%, the clay is about 45%, and the iron slag is half. The role of slag or iron powder is very important. It can help to melt and reduce the difficulty of calcination, and also improve the color and strength."

"Understood! Immediately arrange for manpower to set up a special kiln and, according to the lord's instructions, fire a large quantity of this '戊' material! Then find a method for grinding it!"

Han Ji's eyes gleamed. Although he didn't fully understand the principle behind it, the property of "not dissolving in water and as hard as a rock" instantly brought to mind countless applications: river embankments, city walls, fortifications, building foundations...

“No rush.” Zhang Xian waved his hand. “Cement is a long-term solution, costing a lot of money and time. Right now, there is another material that is easier to obtain, more effective, and can greatly enhance earthwork.”

"What is it?" Han Ji asked hastily.

“Three-in-one soil!” Zhang Xian smiled.

This product has a long history of use in ancient China and the technology is mature. What he wants to do is to add some optimization based on modern understanding to the traditional formula.

“Take high-quality quicklime slurry, sieved fine river sand, and sieved sticky loess. Ordinary soil can also be used, but it is important to ensure that there are no impurities. The ratio is approximately three parts lime, one part sand, and six parts soil.”

"Lime, sand, and soil?" Han Ji was somewhat puzzled. Could a mixture of these three things be better than pure lime and sand?
"The key lies in 'strengthening' and 'nurturing'!" Zhang Xian explained.

"Mix the three ingredients thoroughly, add water until they can be kneaded into a ball, but crumble when dropped; this is the optimal humidity."

Then fill the mold in layers, and use a heavy stone or iron tamper to compact each layer! Each layer should not exceed three inches, and continue tamping until the surface is covered with slurry and hard and dense.

After compaction, it needs to be covered with damp straw mats or damp soil to keep it moist and allow it to slowly 'grow'. The longer it sits, the harder it becomes!

To verify the effect, Zhang Xian immediately directed the craftsmen to make a traditional three-in-one soil mixture of lime, sand, and a small amount of soil using pure lime mortar.

Then he made an optimized three-in-one soil formula, and made three one-foot square soil test blocks. They were marked, compacted, and placed in a shady place covered with damp grass for maintenance.

Ten days later.

Zhang Xian, Han Ji, and several core craftsmen gathered in the corner where the test blocks were placed. Zhang Xian picked up a small iron hammer.

"Clang!" The first hammer blow struck the traditional lime-sand test block, and the test block cracked, but the crack was deep and the fragments were large.

"Clang!" The second hammer blow struck the optimized rammed earth test block, producing a dull sound! Only a shallow pit and radial cracks appeared on the surface of the test block, and the overall structure remained intact! Zhang Xian struck it several more times before finally breaking it open completely. The cross-section was as dense as coarse sandstone, with tightly bonded particles!

"Hiss..." The craftsmen gasped, their eyes filled with disbelief.

The same soil, sand, and lime, just with different proportions and processes, can result in such drastically different strengths!

“This is ‘New Three-in-One Soil’!” Zhang Xian said with a smile.

He derived the new formula after extensive theoretical calculations, and the results of this initial experiment were indeed very similar to those he had calculated.

Thanks to math, physics, and chemistry, I'm truly fearless anywhere in the world.

He waved his hand: "This material is readily available and easy to make. The key is just two words: 'ramming' and 'curing'! It can be called 'new three-in-one soil'! Although it is not as strong and fast as cement, it is more than enough for camp foundations, city wall repairs, ordinary houses, and even road paving, and it is also inexpensive!"

Han Ji nodded repeatedly. He picked up a piece of broken clay, feeling its heavy texture, and looked at the gray-green cement test block next to him. It was as if he could see a brand new picture of the defense fortifications and infrastructure of Luqi and even the entire Bingzhou!
Our lord's talent is truly extraordinary!

"Your Excellency has arrived." Zhang Xian's voice pulled him back to reality.

"The method of cement making is based on the secret techniques of the Jiaqi camp, which are fundamental. Reliable craftsmen were selected, and a workshop was set up with these few as the backbone. It was placed in the craftsmanship area of ​​Jiaqi camp and strictly guarded. The formula and process must not be leaked!"

As for the method of using mortar and lime, first recruit farmers during their off-season to teach it, repair roads and houses, and benefit the people.

"By the way, if you're not on a labor service contract, remember to pay your wages."

"Yes! I understand the importance of things!"

Han Ji solemnly accepted the order, already considering the candidates and the location in his mind.

(End of this chapter)