#STAR WARS REBEL BASES UPGRADE#

On planets where there isnвЂ™t even seawater, water is too dense and precious to use for anything but keeping humans alive. The Middle East on Earth is largely desert, but thereвЂ™s still a lot of concrete production, much of it made with desalinated seawater, which is expensive. Given that concrete needs water to set, a planet without water would prove tricky. But how did they make all that concrete in the first place with so little water? So thankfully for General Leia and co, the mountain base was in a good enough condition to resist the bombardment вЂ“ just long enough for Luke Skywalker to intervene. In such a dry environment, corrosion wouldnвЂ™t happen. Crait has very little water, or none at all.

Were the Rebels foolish to build reinforced concrete bases where salt is everywhere? Actually, this type of corrosion needs a certain level of humidity in the air. In that particular case it is believed that salts carried in the sea air accelerated the deterioration of the structure. This is sometimes known as вЂњconcrete cancerвЂќ and has been a contributing factor in several engineering disasters on Earth, including the collapse of the Morandi bridge in Genoa in 2018. But if COв‚‚ in the atmosphere and chloride in the salts diffuse into the concrete, the steel can corrode, blister and weaken the concrete by expanding. Reinforced concrete contains steel rods to make it stronger and resist bending. Star Wars is a fantasy film firmly based on America's real conflicts But in fact, salts can be one of the most destructive substances for reinforced concrete. Compared to the laser cannons of the First Order, salt would seem the least of the rebelsвЂ™ worries. Outside lie the vast salt flats and the attacking Imperial forces. The rebels regroup in an old base built into a mountain thatвЂ™s protected by colossal, metal blast doors, supported by a reinforced concrete structure. They take shelter on the barren planet of Crait, covered by flat, dried up salt lakes. In 2017вЂ™s The Last Jedi, the rebels were almost wiped out again by the pursuing Imperial fleet. This quick-hardening ability allowed the French Army to build gun emplacements quickly in the first world war, and could have helped fortify rebel defences on Hoth. This reduces how long the вЂњdanger zoneвЂќ lasts, during which the cement must be protected from freezing. Engineers on Earth have a better solution вЂ“ they use special rapid-hardening cement that contains calcium aluminates.

#STAR WARS REBEL BASES UPGRADE#

Engineers are currently using this to upgrade the Rothera research station in Antarctica вЂ“ the most similar place to Hoth there is on Earth.Д«ut shipping all that concrete through space isnвЂ™t practical.

So how did the Rebel engineers get around this? A cheat solution for small structures is simply to make the concrete in a place itвЂ™s not freezing, and then bring it in. If the water in the concrete mix is frozen solid, it canвЂ™t take part in the hydration reaction, and so the concrete canвЂ™t develop its strength. The base is built into subterranean caves, but concrete is still needed for the roofs and floors of the spacecraft hangars, and the defensive laser cannon emplacements.Д«ut how could they make all that concrete when temperatures on Hoth are consistently below 0вЊ? Concrete doesnвЂ™t set by drying out, but by a hydration reaction, which consumes water. Fortunately, General Leia and co are able to defend Echo Base long enough for their allies to evacuate. The Empire have cornered the remnants of the Rebel Alliance on the ice planet, Hoth. At the start of The Empire Strikes Back, things are looking grim.

Star wars rebel bases