| Abstrakt: |
In this paper, a new type of unfired light aggregate based on phosphogypsum was prepared and its properties were tested. The curing mechanism was analyzed according to the characterization of light aggregate. The minimum apparent density is 1277 kg/m³ when the content of phosphogypsum is 54%. The minimum bulk density is 953 kg/m³ when the content of phosphogypsum is 51%. When the content of phosphogypsum is 45%, the maximum 21 d cylinder compressive strength is 5.23 MPa, and the minimum water absorption is 25.5%. Response surface model was used to analyze the effects of fly ash, calcined tailings and quicklime on light aggregate compressive strength. Under the optimized conditions of m(fly ash):m(calcimed tailings):m(quicklime) = 23.53-10.32-2.88, the 21-day compressive strength predicted by the system is 5.56 MPa. In fact, the 21-day compressive strength is 5.42 MPa. At the same time, the water absorption of light aggregate is 24.5%, the bulk density is 952kg/m³, and the apparent density is 1241 kg/m³. Through microscopic analysis of light aggregate, it was observed that tabular phosphogypsum was inserted in the geopolymer grid of hydrated calcium aluminosilicate, acicular ettringite and calcium zeolite were filled in the pores. All material finally reacted and solidified to form unfired light aggregate. [ABSTRACT FROM AUTHOR] |
