The document discusses the use of alkali-activated slag and fly ash as environmentally friendly alternatives to ordinary Portland cement. Alkali-activated slag concrete was made using sodium silicate, sodium hydroxide, sodium carbonate and potassium hydroxide activators. Testing found that sodium hydroxide-activated slag concrete had the highest compressive strength, while potassium hydroxide-activated slag concrete was second best. Alkali-activated slag and fly ash concrete was also made and tested, with sodium hydroxide and potassium hydroxide, and potassium hydroxide was found to produce the highest strengths. The use of these alkali-activated concretes could provide more sustainable alternatives to ordinary Portland cement concrete