I am a believer that industrialization is a root of unsustainable practices. I was pondering on what can be considered as a genuine sustainable living. When I try to understand how can mankind change their ways to be truly sustainable, I feel the ways of living of indigenous peoples can be considered as a showcase of how we have to adapt ourselves to the simple ways of living alongside nature. But again, if such a living was to be practiced throughout the world, will indigenous living materials such as bamboo and wood be sufficient for the construction of houses of such a world? Whereas, concrete is a industrialized material and is the most used material in the world for building houses, mainly due to its availability and cheap price. So is using concrete more sustainable than building a house say with wood? Bamboo is an alternate choice which is very sustainable but again bamboo constructions need to be renewed every few years, which is kind of a hassle.
Concrete is made from sand, grit and (portland) cement; portland cement is made primarily of clinker.
Almost all concrete at the time of writing is unsustainable. The extractive industries that provide the aggregates are very destructive, and the clinker manufacturing process releases huge amounts of carbon dioxide: about half a tonne just from the chemical reaction, for every tonne of cement. In addition, the high (1500°C) temperatures needed are usually generated by burning fossil fuels, releasing more CO2. (source - the Dean et al paper mentioned below)
However, that's a product of the way it's currently manufactured: it doesn't need to be this way.
There's a lot of research going on into making concrete sustainable, by looking both at the manufacturing, and at the end-of-life handling.
At the end of its life, uncontaminated concrete can be crushed or ground, and reused as aggregate in construction.
Timber has the advantage of locking up carbon: we need a lot more sinks for carbon, and a lot fewer sources, so locking up carbon in structures is definitely a plus. As long as the timber is sourced sustainably, but a lot isn't. There are various accreditation schemes in place that are working towards more sustainable wood sourcing.