Contributed Photo: A plume of fly ash gets expelled over Tri County Materials on Wednesday morning.
By Jon Johnson
SAFFORD – An accidental release of fly ash at Tri-County Materials on Wednesday morning caused a dust plume over the facility, leaving spectators to wonder what had happened. The business is located at 3215 U.S. Highway 191 at the intersection with E. Solomon Road.
According to an employee, they were loading a cement truck when a valve stuck open and caused a lot of fly ash to be expelled into the air.
Fly ash is made from residue left from burning coal and is used as a substitute for cement. The employee advised that Tri-County Materials uses both fly ash and cement in its concrete preparations.
According to the National Precast Concrete Association (NPCA), fly ash reacts with lime to form a hydrated calcium silicate – the same cementing product in Portland cement. The reaction of fly ash with lime in concrete improves strength and it is typically added to structural concrete at 15 to 35 percent by weight of the cement, but up to 70 percent is added for mass concrete used in dams, roller-compacted concrete pavements, and parking areas, according to the NPCA.
No injuries were reported due to the expelling siliceous material but workers’ vehicles were covered by the dust when it returned to the ground.
Tri County Materials Inc. is a ready mix concrete supplier in Safford and also sells and delivers sand, ABC, decorative rock, gravel, and concrete blocks.