Performance Characteristics of Concrete Produced with Fluidized Bed Combustion Ash Residue

Abstract

Over the last five years, the Kentucky Energy Cabinet (KEC) and the Tennessee Valley Authority (TVA) have developed and demonstrated the production of concrete from atmospheric fluidized bed combustion (AFBC) spent bed (SB) ash, and pulverized fuel ash (PFA). This AFBC concrete contains no cement and relies on the reaction of residual lime in the SB ash to react with the pozzolan PFA to form cementitious products. The SB ash is prehydrated in order to reduce exothermic lime hydration reactions and minimize molar volume expansion. Laboratory tests were conducted to establish the performance characteristics of AFBC concretes relative to conventional concrete. AFBC concretes exhibit slower strength gain characteristics, but long term (60 day), unconfined compressive strengths of 5,000 psi have been documented. This slow strength development is typical of pozzolanic concretes. AFBC concrete is more flexible and less brittle than conventional Portland cement concrete, as evidenced by its much lower modulus of elasticity. Setting times for AFBC concretes are extended, requiring the use of accelerators under certain applications. Field demonstrations of the AFBC concretes in ready mix concrete, masonry units, and road base applications have indicated excellent workability and finishing characteristics and confirm the laboratory performance characteristics.The paper describes the results of the testing program with emphasis on the ash chemistry/conditioning, the performance characteristics and field demonstrations.

High Volume--High Value Usage of Flue Gas Desulfurization (Fgd) by-Products in Underground Mines

“…In comparison, the nonprehydrated grouts exhibited significantly lower compressive strengths under identicrd curing conditions ( Figure 19). Furthermore, the level of prehydration exerted a significant effect: the optimum prehydration moisture content was determined to be 10-150/~which is similar to the optimum found by Bland et al (1987) for FBC bed ash-based grout.…”

Structural-grade concrete containing FBC and PCC residues. Part I: Non-cement concrete

“…Conventional PCC fly ash has long been used in cement and noncement based mixtures to enhance their fresh and hardened engineering properties (Bland et al, 1988;Camilleri et al, 2006;Cheriaf et al, 1999;Chindaprasirt and Rattanasak, 2010;Chindaprasirt et al, 2011). According to the ASTM definition (ASTM, 2012), class F fly ash (with calcium oxide content of less than 10%) is pozzolanic, whereas class C fly ash (having more than 10% calcium oxide) also has cementitious properties.…”

Final Technical Progress Report

“…This fly ash was mixed with CaO and DW for pozzolanic reaction and hardening hardly Recycling Expansion was not well developed, even though the density was lower than water density (62.4 pcf) as shown in Table 70. Low density was due to lower specific gravity of this FGD ash compared to other fly ash samples [47]. The density of Specimen 22 cured for 7 days was 54 pcf, and it was 13% lighter than water density as displayed in Figure 60.…”