The Sduty Of Properties Of Ground Circulating Fluidized Bed Combustion Ashes In Cement And Concrete

Circulating fluidized bed combustion (CFBC) technology is advanced because it can meet the demand of environment protection, but the byproducts, namely CFBC ashes, which containing the high sulfur minerals can cause volume expansion in the process of hydration and it are still something new to most people . As a result, the utilization of them and even the further promotion of the technology are seriously hampered. This paper use a typical CFBC bed ashes as research objects. The test studied the ground CFBC as cement admixture and concrete admixture.The granule morphology of CFBC ashes were investigated by scanning electron microscope(SEM). The properties about the ground CFBC as cement admixture and concrete admixture is studied by strength, volume stability, durability .The hydration products were studied by X-ray diffraction (XRD) .The results showed:For ground CFBC ashes, because the grinding only undermines its macro-structure, so the micro structure is almost the same with the original CFBC ashes. The particles of them are all irregular and loose textured, but the grinding fineness of ground CFBC ashes has greater impact on its macro-performance. Tests showed that the grinding fineness has greater impact on the performance of ground CFBC ashes, including compressive strength ratio, liner expansion ratio and the compatibility with the reducing agent, but has little compact on the water requirement of normal consistency of ground CFBC ashes. With the increase of grinding fineness, the activity of the ground CFBC ashes and the liner expansion ratio is also increasing, the compatibility with reducing agent is getting weaker. Especially, when the surface area is more than 320㎡/㎏, the specimen is cracking and broken because of the expansion of the volume and the compatibility with the reducing agent is more worse.In the study of ground CFBC ashes as the cement admixture, because of the high SO3, the system of CFBC-clinker is the basic system. The compressive strength is increasing with the increased amount of the ground CFBC ashes, but is reducing when amount exceed 30%. The liner expansion ratio when cured in water is increasing with the increased amount of the ground CFBC ashes almost.In the study of ground CFBC ashes as the cement admixture, because of the high SO3, the system of CFBC-clinker also is the basic system. The compressive strength is increasing with the increased amount of the ground CFBC ashes, but is reducing when amount exceed 30%. The liner expansion ratio when cured in water is increasing with the increased amount of the ground CFBC ashes almost. The test also studied the durability of the concrete with the system of the ground CFBC ashes-clinker. When the amount of the ground CFBC ashes is in a certain content, the ability to resist chloride ion penetration is good and the carbonation depth is not changed obviously, but when exceed the especial amount, the carbonation depth is deepening. Finally, the test studied the performance of the concrete with the system of the ground CFBC-clinker when adding naphthalence series water reducer.