Dwarves in DF do not use any of the many ceramic and cementing technologies that would fit in with their technology level. While some of that might simply be that they prefer carved rock construction, it seems to me that they should still be able to make pots, bricks, concrete and other similar things even if they don't like the resulting products as much as granite or obsidian (after all, they already make things out of leather and wood). I know there have been proposals and suggestions for some of these items, but I thought I'd try to get a bunch of related suggestions in one place.
The simplest change would be to add ceramic crafting to the existing kiln workshop. Clay would need to be gathered in a similar way to sand, then fired into various items, such as pots (which would work like barrels). Different kinds of clay might make different kinds of pottery, just as different regions of Earth had greatly different ceramic traditions. Glazing could also be applied to ceramics to decorate and change the color of the finished piece, in a multiple step production process.
In addition to making clay mugs, craft items and other things, clay bricks could be made and fired for use in construction (they would work just like stone blocks). Of course, the building of brick or stone walls should require mortar to hold the bricks or stones together. While a clay based mortar is possible, a better mortar would be a form of cement.
There are several cement products that could fit within DF technology. The ancient Greeks and (especially) the Romans used cement mortar and various forms of concrete in their constructions, some of which have survived for thousands of years to the present day. It should be noted that I'm talking about ancient forms of cement which are not the same as what you would get if you buy a bag of cement from a store. Modern "Portland" cement was invented in 1796 and so does not fit in with the DF technology base.
The key substance for making classical cement is lime. Lime has several forms, which modern chemistry has shown to be two different Calcium based compounds. They can both sometimes be called "lime", depending on the the context.
Calcium Oxide (CaO), known as burnt lime or quicklime, is a dry white powder. It comes from heating limestone or chalk in a kiln to dissociate Carbon Dioxide (CO2) from the Calcium Carbonate (CaCO3) in those minerals. Quicklime is highly caustic and reacts strongly with water (giving off heat). It has some uses beyond cement, but probably not many that are important to DF. In DF it could be made in the already existing kiln workshop.
Calcium Hydroxcide Ca(OH)2, known as hydrated or slaked lime, is what you get when you add some water to quicklime. Depending on how much water is added, you can get either a dry white powder (which can be stored) or a wet paste. When wetted and then allowed to dry, slaked lime gradually turns back into limestone by absorbing CO2 from the air (this is why lime based cement sets). In DF, it could be made in an alchemist's workshop by combining a bag of quicklime with a bucket of water.
The simplest form of cement is slaked lime mixed with water and sand as a filler. This is still used as mortar even today, though it doesn't hold up to water as well as other formulations. This was the form of cement used in Medieval Europe when other kinds of cement were forgotten. The common proportions for this mix were 1 part lime to 2 or 3 parts sand.
More sophisticated formulations add a "pozzolan" substance, such as volcanic ash, making the chemistry more complicated, but resulting in a cement that sets faster and holds up better to water. Pozzolans are named after the first known example, a volcanic ash called pozzolana found near mount Vesuvius (though it also occurs around other volcanoes). Volcanic ash was widely used in cement made by the Greeks and Romans. Powdered brick and other fired clay products were used as a man-made pozzolan in some Roman construction.
Pozzolanic substances contain silica (and often alumina). It brings silicon (and aluminum) into the cement in a chemically available form. They react with slaked lime to form a variety of compounds that add strength to the cement (the chemical reactions are much more complicated than in plain lime cement). Many mixtures of these cements are known as "hydraulic" because they will harden even when fully submerged in water. Some limestone deposits already include pozzolanic minerals and naturally form hydraulic cements.
Lime-Pozzolanic cement was used as as mortar by the Romans for most of their structures, especially water related civil engineering projects like aqueducts and bridges. These cements still take a relatively long time to set fully (days to months) but less than for non-hydraulic lime cement. It is not clear why these superior forms of cement were forgotten in Europe during the Dark Ages, given how widely the Romans used their cement technologies.
In DF, volcanic ash might be found as a new soil type near volcanoes and magma pipes. It would need to be gathered like sand, in bags. The alchemist's workshop could have a cement-mixing job available, where slaked lime, water and sand would be combined, optionally including volcanic ash to make hydraulic cement. The resulting product could be used as mortar for wall building, or further mixed into concrete. If it was not used after a while, it would harden into a cement block.
Concrete is made by adding an aggregate of gravel or medium sized crushed stone to cement. The wet concrete can then be poured into wooden forms to create almost anything, including blocks, floors, whole walls, heavy tables and chairs, large doors, and all sorts of other large objects. If any of the "Realistic Mining" ideas gets implemented, there may be a great excess of scrap rock for the dwarves to get rid of, and concrete would be one positive way to use it.
Another cement product is plaster for finishing walls, both internally and externally (plaster can also be called stucco or render). Lime plaster is basically just a form of fine cement that you spread over an wall to improve it's aesthetic properties and to seal it from moisture and dirt. In DF, plastered walls probably can't be engraved, but they could have frescoes added to them by the plasterers.
Whitewash is effectively a very thin plaster that can be applied with a brush, like paint. It is made from slaked lime and chalk. Wood and stone surfaces are easier to keep clean if they are whitewashed, but it is not a good paint for indoor living spaces because it will rub off onto anyone who touches it, making a white mess on their clothes. I'm not sure if it has any place in DF, but I'm including it in my suggestion for completeness.
Let me know what you think of these ideas. Are there additional important uses of ceramics or cements? How would adding any of these change the game around? What kinds of implementation challenges might they pose for Toady One?
One thing I like about my ideas is how they can combine well with other ideas:
For example, if digging was changed to not produce stone items (as suggested in a recently resurrected thread), concrete and brick might become important building materials. If mining gets changed in the other direction and starts producing realistically huge quantities of scrap rock, a lot of it could go into concrete production instead of just being dumped.
As another example, if tools (such as hammers and chisels) were required for civilian labor like stone carving, less tool-intensive production systems like brick and cement might be essential in forts that don't have a metal industry yet.
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Topic: Ceramics and Cements: Pottery, Bricks, Mortar, Concrete, Plaster and Whitewash (Read 8655 times)