Environmental issues caused by the production of Portland cement have necessitated its replacement by waste materials like fly ash which has been proven to be quite beneficial environmentally and economically. Therefore, this research project was focused on the development of sustainable construction materials using 100% of high-calcium fly ash with KOH based alkaline solution. Experimental work was conducted to determine concrete properties like compressive strength, flexural strength, setting time, and slump. In the phase I of the research, CNTs were also used to study its effect on geopolymer mortar. The results derived from the experiments show that mortar and concrete made with 100% fly ash C needs alkaline solution to reach properties established by Portland cement concrete. However increased amount of KOH generates heat making the concrete to set faster without forming a proper bond. Furthermore, the addition of CNTs makes the mortar sturdier than the one without CNT.