In the wars of the Qin Empire, many times the next battle plan was carried out only after ensuring sufficient logistics.

Of course, this point was not the first of its kind in the Qin Empire, but it was a kind of operational foundation that must be achieved in military history.

As the saying goes, the emperor is not bad for hungry soldiers.

The existence of warehouses is an important means of ensuring the storage of military materials.

In the current Qin Empire, Zhang Jiashi attaches relatively much importance to the army warehouse.

But in many cases, hollowing out the mountain to serve as a mountain storehouse is not the method that Zhang Jiashi hopes to take.

Because the mountain warehouse is a relatively expensive and manpower demand is also a kind of warehouse construction.

However, one of the main means of building large and even giant warehouses during the Qin Empire and even the Han Empire, Shancang had some favorable factors of its own.

For example, in terms of defense, even if Yamakura is largely unable to resist the offensive of foreign enemies, as long as the door of Yamakura is blocked, then it will be enough for the offensive personnel to spend more time, manpower and material resources to reopen Yamakura.

Underground warehouses also have this benefit, but in some cases the construction requirements for underground warehouses are even higher than those of mountain warehouses.

Therefore, under the current shortage of manpower, the new way of building military grain warehouses of the Qin Empire, Zhang Jiashi adopted more of a house-style warehouse construction method to build warehouses in some important areas, and put ordnance and grain in preparation for war.

But in many cases, the houses of this period have great flaws as a warehouse, and once they meet an offensive, the defensive ability of these warehouses can only be hehe.

However, there is no way to solve this situation, and Zhang Jiashi has thought about whether to make drum cement to improve the overall structural level of the house.

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Cement is a very common, even mainstream, building material in later generations.

But cement can be said to be a result of modern industrial development:

In 1756, the British engineer J. Smitton discovered when studying the properties of certain limes hardening in water: to obtain hydraulic lime, it was necessary to use limestone containing clay to fire, and the ideal composition of masonry mortar for underwater construction was made of hydraulic lime and volcanic ash. This important discovery laid a theoretical foundation for the research and development of modern cement.

In 1796, the Englishman J. Parker fired a kind of cement from marl, which has a brown appearance, much like a mixture of lime and volcanic ash in ancient Roman times, and named Roman cement. Because it is made of natural marl as raw material and fired directly without ingredients, it is also known as natural cement. It has good hydraulic hardness and fast setting characteristics, and is especially suitable for projects in contact with water.

In 1813, the French civil engineer Francis Pican discovered that cement made from a three-to-one mixture of lime and clay performed best.

In 1824, British construction worker Joseph Asputin invented cement and obtained a patent for Portland cement. He used limestone and clay as raw materials, combined in a certain proportion, calcined the mature material in a vertical kiln similar to burnt lime, and then ground it to make cement. It was named Portland Cement because its hardened color was similar to the stone used for construction in Portland, England Island. It has excellent architectural performance and is of epoch-making significance in the history of cement.

In 1871, the construction of a cement plant began in Japan.

In 1877, Crampton of England invented the rotary furnace, which was reformed into a better rotary furnace by Lansom in 1885.

In 1889, near the Kaiping Coal Mine in Tangshan, Hebei Province, China, a Tangshan "Fine Cotton" Plant was set up to produce with vertical kilns. In 1906, on the basis of the plant, Qixin Ash Company was established, with an annual output of 40,000 tons of cement.

In 1907, Bée in France used bauxite from aluminum ore instead of clay and mixed limestone to make cement. Because this cement contains a large amount of alumina, it is called "bauxite cement".

In the 20th century, while continuously improving the performance of Portland cement, people successfully developed a number of cements suitable for special construction projects, such as high-alumina cement, special cement, etc. There are more than 100 types of cement in the world, and the annual output of cement in 2007 was about 2 billion tons.

This means that although cement appeared relatively late, its technological level is not strictly speaking.

However, in many cases, the construction method of civil engineering materials, which has been gradually developed at this time, has great shortcomings compared to cement construction.

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Ancient Chinese architecture used timber frames as the load-bearing structure of houses.

The timber-framed beam and column system was initially completed and widely used in the Spring and Autumn period before the Common Era, and was more mature in the Han Dynasty. The timber structure can be roughly divided into beam lifting type, bucket type and well dry type, and the beam lifting type is the most common. The beam-lifting structure is to erect columns on the column base along the depth of the house, erect beams on the columns, overlap several layers of melon columns and beams on the beams, and then erect ridges and melon columns on the topmost beams to form a group of roof trusses.

The parallel two groups of frames are connected to the upper end of the column with transverse fangs, and purlins are placed on the beam heads and ridge melon columns of each layer to connect the frame and the bearing roof. Purlins frame rafters form the skeleton of the roof. In this way, two sets of structures can form one, and a house can be one or more rooms.

Bucket is the most special component of Chinese timber frame architecture. The bucket is a bucket-shaped skid, and the bucket is a bow-shaped short log, which is crisscrossed layer by layer and superimposed into a group of large and small brackets, which are placed on the column head to support the load of the beam frame and the eaves that are raised outward. In the Tang and Song dynasties, the dou bao developed to its peak, from a simple cushion and eaves member to a circle of "well" grid composite beams connected to the beam and placed on the column network. In addition to lifting the eaves outwards and supporting the ceiling inwards, its main function is to maintain the integrity of the timber frame, which has become an indispensable part of large buildings.

After the Song Dynasty, the opening of the wooden frame was enlarged, the column body was heightened, and the bucket used on the nodes of the wooden frame was gradually reduced.

In the Yuan, Ming and Qing dynasties, the forehead and the beam fang were used between the stigmas, the overall structure was strengthened, the shape of the bucket became smaller, and it no longer played a structural role, and the arrangement was more dense than that of the Tang and Song dynasties, and the decorative role was more and more strengthened, forming an ornament that showed the difference in rank.

The advantages of the timber frame are: first, the load-bearing structure is separated from the maintenance structure, the weight of the building is all supported by the timber frame, and the wall only plays the role of maintaining and separating the space. Second, it is convenient to adapt to different climatic conditions, and the height of the house, the thickness of the wall, the choice of materials, and the location and size of the doors and windows can be determined according to the different cold and warm conditions in the region. Third, due to the unique nature of timber and the flexibility of structural joints, even if the wall collapses but the house does not collapse, it is conducive to reducing earthquake damage. Fourth, it is convenient for local materials and processing. In ancient times, the middle reaches of the Yellow River were densely forested, and wood was easier to process than bricks and stones.

Some of the defects of ancient Chinese wooden architecture are that wood does not last as long as masonry, and it is afraid of fire and is susceptible to fire.

Timber is becoming less and less, and the Chinese ancestors prefers the combination of architecture and the natural environment, the layout develops in the plane direction, and the single-storey building is the mainstay, and the relative attitude towards the solidity of the building does not require a thousand years of immortality, but also hopes that the building is easy to transform.

Timber construction is much superior to stone construction in terms of saving materials, labor, and construction time.

But in many ways, even carpentry buildings can't compare to concrete buildings when it comes to time.

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Zhang Jiashi wanted to make reinforced concrete, but he was not very hopeful about the hardness of pig iron, so he planned to try to make a small amount of reinforced concrete.

If this kind of reinforced concrete, which is mainly made of pig iron, is really useless, then he can only make relatively rudimentary concrete buildings.

Concrete is said to have appeared in ancient China, of course, this is a very different existence from modern concrete:

Archaeologists have found that 5,000 years ago, the ancestors of Lingjiatan were not only able to make exquisite jade tools, but also began rice agriculture, raising or hunting pigs, deer, birds and birds and other animals to enrich the diet of varieties. In addition, in the construction of houses, they have learned similar to reinforced concrete: "digging grooves to fill the soil, wood bones to support the mud wall" construction technology.

5,000 years ago, the Lingjiatan people did not simply build houses, it has been proved that the Lingjiatan people at that time already knew the construction process of "digging grooves and filling in the soil, and supporting the mud walls with wooden bones", which is very similar to the current reinforced concrete.

The staff said that the primitive ancestors used the fire-burned soil as the filling material for the foundation groove and the wall, used wooden sticks as the support column of the wall in the foundation groove, and then filled the red-boiled soil clods, and applied thick clay on the surface of both sides of the wall, and even some of them may be reinforced with reed rods.

But what Zhang Jiashi wanted was the kind of cement made of lime and clay that was more primitive but basically not difficult to make.

Zhang Jiashi did not think about making "Roman cement" and "Portland cement", but there is no doubt that Roman cement needs to add volcanic ash, which makes Zhang Jiashi say hehe.

Although "Portland cement" is relatively more convenient, from the history of the invention of Portland cement, this kind of cement is actually difficult to produce in large quantities in the production environment of the Qin Empire:

In 1756, a lighthouse on the Channel Islands of England suddenly caught fire and burned down. This is really fatal, you must know that this is the most important lighthouse at the southern end of the English Channel, without which it would affect the navigation of countless ships. The British government ordered engineer Smirton to rebuild the lighthouse as quickly as possible.

Smithton immediately ordered the limestone to be transported to the island where the lighthouse was located, so that the limestone from the island could be burned and rebuilt from the island. Having completed similar projects many times, Smithton is confident that the rebuilding mission will be completed on time.

Two weeks later, the limestone arrived, and Smitton rushed to the unloading dock in high spirits. When he saw these limestones sent from across the mountains and seas, he couldn't help but exclaim: "It's really unlucky, why is this stone black? It is mixed with too much soil, and it is not a joke to build a high-standard lighthouse with such inferior raw materials?" However, time did not allow him to transfer high-quality limestone, so Smithton had to use these inferior raw materials for firing.

Unexpectedly, Smithton was a blessing in disguise. The lime burned from this batch of limestone is surprisingly good, and the stone is cemented to a point that has never been stronger. When the overseer informed Smith of the unexpected result, he jumped in surprise. Then he calmed down again, "There is a famous hall in this lime, you have to check it." Smithton immediately examined the limes and found them to be impure, containing up to about 20 percent clay.

"It seems that it is these clays, which are considered impurities, that play a good role. Later, Smitton consciously calcined the clay in the right combination with the limestone, and the lime properties were indeed ideal. Smithton happily recounted his experience.

Smithton's practice soon spread throughout Europe and aroused the interest of many people, and people imitated it with great success. Around 1820, when the Russian architect Cheryev was working in the Moscow region, he used this method to burn lime and build many buildings, the most famous of which was to restore the walls of the Kremlin.

"Can we make it better?" said an English craftsman named Yasputin trying to improve on Smirton's invention. He thought of the ancient Romans' practice of adding volcanic ash to lime in order to enhance the cohesion of lime, so he came up with a new idea: volcanic ash is the product of rock melting at high temperature, so is it similar to volcanic ash when grinding pottery, brick and tile chips into fine powder?

Yasputin tried it, and it worked well. Later, he thought that the cinder after the high-temperature combustion of coal and the high-temperature smelting slag flowing from the iron-making blast furnace might also have similar functions, and the test also confirmed that his idea was right.

In 1824, on the basis of trial and error, Yasputin summed up the ratio between various raw materials such as lime, clay, slag, etc., and the method of producing this mixture. Yasputin patented his invention, which was used to produce what we call "cement" today. Because the color and strength of Yasputin's cement after hardening were similar to the stone produced on Portland Island in England at that time, people called it "Portland cement".

One of the earliest large-scale applications of "Portland Cement" was the construction of a tunnel across the bottom of the River Thames. It spread rapidly around the world, with cement factories in France and Germany in 1840 and 1855 respectively. Now, cement has become an indispensable material in modern human life.

So relatively speaking, it basically only needs cement made of clay and lime, which Zhang Jiashi himself thinks can be more producible.

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