If the US is going to build a wall on its border with Mexico, it’s going to take a lot of concrete - millions of tonnes, in fact. But this is a tiny amount compared with China’s concrete use. It’s often said that China used more concrete between 2008-2011 than the US did in the whole of the 20th Century. It sounds astonishing - and is it true? Wesley Stephenson finds out.

After comments by author Chimamanda Ngozi Adiche divided opinion over transgender women, we speak to members of some of Nigeria’s secret gay and transgender groups who rely on each other on social media for support. Also, Joey Daley from Ohio has documented his mother Molly’s dementia. One film in which she failed to recognise him for the first time was viewed nearly 2 million times. Joey speaks to BBC Trending about how it feels to care for someone with dementia.

And Lee Kumutat examines why blindness comes to define the identity of people who have little or no sight. She talks to people in Jamaica, Ghana, Scotland and California about how they navigate a world which seems to see them as either inspirational or deserving pity. Or both.

Image: Getty/Credit: David McNew / Stringer