The first condition for soil cement is white ash, I know that lime is fired at high temperature with limestone, and the specific point is that there are also calcium carbonate stones that can burn lime.

But there are no calcium carbonate stones on this island, but we have better raw materials, which are large quantities of shells and corals, both of which are found everywhere here, and they definitely contain more calcium than any kind of limestone.

Seashells and corals are easy to find, and islands are everywhere, and even the island's sandy beaches are made from fragments of corals and shells, but collecting them can be hard work.

It's easier to collect shells, but they don't have a lot of them, and many of them belong to mussels, which I collected after drifting to the island, and the shells are very thin and don't seem to be very suitable for lime burning, but some conch shells can be used, but there are not many of them.

So I identified the main raw material of lime as corals in the sea, so I had to go down to the sea to salvage corals, and the island is surrounded by the sea and belongs to the tropics, so there are a lot of coral reefs here, and there are many dead corals washed ashore by the sea, I just need to pick them up and concentrate them, and I don't need to go into the water to collect them.

Luckily, I didn't use a lot of corals, I spent half a day collecting a lot of corals and shells, and then chiseled the corals into fist-sized pieces with a stone axe, which was good for firing.

Coral and shells can only be used to make lime, and other materials for making earth-based cement are not available on this island, but this island is a volcanic island.

The island is full of volcanic rocks, and I can try to use volcanic rock instead of other high-temperature firing materials, after all, volcanic rock is a stone formed by the heat of volcanic eruptions, but it should also be fired at high temperatures.

Volcanic rocks are everywhere, and it didn't take long for me to collect a lot of them, and then it was up to me to see if I could burn them into cement.

I spent a few days preparing the fuel, of course, the fuel available on the island is wood, the highest burning temperature of wood can reach about 1000 degrees, and the burning of lime should be above 1000 degrees, so the temperature of wood burning is barely possible, of course, the temperature of making wood into charcoal will be increased.

However, I have also seen on the Internet that it is possible to burn lime directly from wood, and it should be easier to burn coral and shellfish loosely.

At first, I wanted to build a kiln with sand, but the viscosity of the sand was too low to be molded, so I had to put the wood and coral first, a layer of wood and a layer of coral, a total of four or five layers, because of the lack of experience, I put a lot of wood, so that the firing time can be extended, the success rate will be higher.

After stacking the wood and coral, I put the wet sand on the wood and coral, and then slapped it hard to make a big grave, and finally I could light it by digging a few vents.

I used the same method to build a smaller kiln to burn volcanic rock, and I added more wood in this kiln, and I thought it would take a little longer to burn volcanic rock.

In this way, I lit the fire and started firing, during which there was a very important step to operate, that is, when I saw that the fire had ignited all the wood, I had to block all the vents and leave only one vent, reduce the speed of wood burning in the kiln, and slowly calcined the effect was better.

The next thing is to wait,,,,,

However, I made a mistake, because the sand was not sticky and therefore unsupportive, and the lime kiln collapsed on the second day of firing, and there was no way to remedy it, so I had to resign myself to fate.

After two or three days of firing and two days of cooling, I opened the kiln on the fifth day, and when I opened the kiln, I didn't have any bottom in my heart.

When I opened the kiln, I felt terrible, and when I took out the first piece of coral, I found that it was not fired, because the lime was successfully fired, and the rock would change color and become lighter, and the coral rock in my hand was blackened and the weight did not change at all.

It seems that it has failed, but I am unwilling to continue to search, muttering to myself whether it will not succeed in any of them.

When I picked up the bottom layer, I finally found that some coral rocks and shells had been successfully fired into lime, and I shouted and cheered excitedly, and this joy of success really gave me a lot of confidence.

It seems that the situation is not as bad as imagined, although the kiln collapsed, but I still have half of the lime successfully fired, and half of the volcanic rock has become lighter, and the burned volcanic rock is more loose, and can be easily smashed with a stone axe.

Now I'm going to verify that the lime has been successfully fired, simply by sprinkling water on the burned coral blocks, and doing another experiment to see if the white ash can be mixed with the burned volcanic rock to make cement, and whether it can be waterproofed.

After a short time of sprinkling water on the burnt corals and shells, water vapor rose and snorted, and I knew that the water was reacting with quicklime, which proved that I had successfully fired the lime.

The next step was to crush the volcanic rock, of course, as fine as possible, and then I experimented with the lime volcanic rock in a one-to-one, two-to-one, and one-to-two ratio.

Another experiment was to add the same amount of sand to the cement of each experiment and then conduct a second experiment.

I mix each of the experimental cements in proportion, then make them into a tank to dry and then test their strength and waterproofness.

The final result is very satisfactory to me, this simple soil cement is a success, although the strength is not as good as expected, but the waterproof performance is not bad, especially the lime volcanic rock sand is the most suitable ratio of one to one, strength and waterproofness are the best.

With homemade soil cement I can make a cistern, I decided to make two one-cubicle pools that can hold water for two meals enough for me to use for a year, although I can't use so much water just for drinking, but as the saying goes, those who are prepared are not in trouble.