An old woman at a village gathering in February 2015. The woman couldn't speak English but gave a thumbs-up to Zhang Pengxuan after seeing the photo, which made him very happy.[Photo provided to chinadaily.com.cn by Zhang Pengxuan]

The biggest challenge for Zhang is that it takes one day's flight to fly to China. He said he will never forget the day he watched his newborn baby via webcam.

Despite the long separation from his family, Zhang said he is proud to help bring a change in Africa and he strongly supports China's investment in the continent.