Complex sentence: GigaCrete was invented in the early 21st century by British-born architect and industrial designer Andrew C. Dennis whose idea was to create strong, lightweight, and "green" cementitious building materials.
Split into simpler sentences: GigaCrete was invented in the early 21st century by British-born architect and industrial designer Andrew C. Dennis. The idea was to create strong, lightweight, and "green" cementitious building materials.