Ash collected from the low-sulfur subbituminous coal-fired Foster Wheeler Energia Oy pilot-scale circulating PFBC tests in Karhula, Finland, and from AEP's high-sulfur bituminous coal-fired bubbling PFBC in Brilliant, Ohio, were evaluated in laboratory and pilot-scale ash use tests. Options evaluated for these ashes were construction-related applications, such as cement production, fills and embankment, soil stabilization and synthetic aggregate production, as well as an amendment for acidic and sodic soil and mine spoil as described in Part 2 of this paper. The tests related to construction applications, described herein, led to the following conclusions. (1) PFBC ash does not meet the ASTM chemical requirements as a pozzolan for cement replacement (ASTM C618). However, there is potential for its use as a pozzolan and as a set-retardant (gypsum replacement) in type-IP Portland cement production. (2) PFBC ash shows relatively high strength development (> 2.75 MPa), low expansion (< 0.01%) and low permeability (k < 10−5 cm s−1), making it a viable fill and embankment material. (3) Lime-enhanced (e.g. 3.6 wt% CaO added) PFBC ash develops high strength (> 27.5 MPa), manageable early expansion, and wet-dry and freeze-thaw cycle durability (< 1 wt% loss after 12 cycles), making it a suitable agent for soil stabilization. (4) Synthetic aggregate produced with lime-enhanced PFBC ash develops high crushing strength (> 135 kg), resistance to Los Angeles (LA) abrasion resistance (10–30 wt% loss) and soundness resistance (< 5%), making the ash an excellent material for synthetic aggregate production for construction applications. In summary, PFBC ash appears to be a viable material for use in a number of construction-related applications.