Eco-cement
One problem with the commercialization of this cement, other than the conservatism of the building industry, is that the feedstock magnesite is rarely mined.
Ordinary Portland cement requires a kiln temperature of around 1450 °C.
The reactive magnesia in Eco-Cement requires a lower kiln temperature of 750 °C,[1] which lowers the energy requirements, and hence the use of fossil fuels and emission of carbon dioxide (CO2).
The rate of absorption of CO2 varies with the degree of porosity and the amount of MgO.
A typical Eco-Cement concrete block would be expected to fully carbonate within a year.
Eco-Cement is able to incorporate a greater number of industrial waste products as aggregate than Portland cement as it is less alkaline.
This reduces the incidence of alkali-aggregate reactions which cause damage to hardened concrete.
[2] Eco-Cement also has the ability to be almost fully recycled back into cement, should a concrete structure become obsolete.
To make truly zero CO2 and pollutants emission cement, MIT researchers have come up with a very innovative approach.
The Figure shows the cement production process of this new approach.
[3] First of all, the new approach can replace the use of fossil fuels in the heating process with electricity from clean, renewable sources.
Also, in many regions, renewable electricity is the cheapest energy source we have today, and its cost is still falling.
The high purity CO2 can be used to produce value-added product, and the O2 and H2 may be used to generate electric power via fuel cells or combustors.
This approach can also significantly reduce the water consumption of cement production.
If H2 was used to fuel the kiln, the other half of the water could be condensed from the flue gas.
The research team of Professor Luping Tang from Chalmers University of Technology in Sweden is studying how to use concrete to store electricity.
The researchers added conductive carbon fiber into concrete to replace electrolyte.
Also, the researchers identified the following metals are suitable for rechargeable concrete batteries.
Equipment based on thermoelectric materials does not have any carbon dioxide emissions during operation.
Thus, extensive use of thermoelectric-based cement structures is a reliable way to solve environmental problems.
Generally, cement exhibits slight electron movements because of the presence of n-type conductivity.
Therefore, with the addition of p-type conductive admixtures, hole movements are present, which eventually develops electron–hole distribution in cement composites[5] Thus, a voltage difference is attained and TEP is generated.
The conductivity of the cement-based matrix can be enhanced even when admixtures are added below the percolation threshold.
