Preparation of Foamed Phosphogypsum Lightweight Materials by Incorporating Cementitious Additives

  • Ting WANG School of Civil Engineering, Harbin Institute of Technology, Harbin 150090, China
  • Xiaojian GAO 1 School of Civil Engineering, Harbin Institute of Technology, Harbin 150090, China 2 Key Lab of Structures Dynamic Behavior and Control of the Ministry of Education, Harbin Institute of Technology, Harbin 150090, China 3Key Lab of Smart Prevention and Mitigation of Civil Engineering Disasters of the Ministry of Industry and Information Technology, Harbin Institute of Technology, Harbin 150090, China
  • Jian WANG
Keywords: phosphogypsum, cementitious additives, air foam, strength, microstructure

Abstract

As a byproduct of phosphoric acid industry, phosphogypsum has many environmental problems. In order to recycle phosphogypsum to manufacture lightweight building materials, cementitious additives including fly ash, ground granulate blast-furnace slag and Portland cement were added to improve strength and water-resistance and different volume of foam was added to reduce the bulk density. The results show that hydrated lime can improve mechanical strength and water resistance of PG paste and the optimal dosage of hydrated lime is 6 %. Higher addition of fly ash or ground granulated blast-furnace slag improves the fluidity and delays the setting time of PG paste. The addition of 10 ~ 20 % fly ash results in a little reducing influence and 10 % ground granulated blast-furnace slag leads to an increase of 20.7 % for 28 days compressive strength of hardened PG specimen. The higher addition of Portland cement results in the better mechanical strength and water resistance of PG specimens. The 28day compressive and flexural strength reaches 25.9 MPa and 8.9 MPa respectively for the 25 % Portland cement mixture. PG based lightweight building materials can prepared by the addition of 60 % volume of air foam, with compressive strength of 1.7 MPa, bulk density of 521.7 kg/m3 and thermal conductivity of 0.0724 W/(m·K).

DOI: http://dx.doi.org/10.5755/j01.ms.25.3.19910

Author Biography

Xiaojian GAO, 1 School of Civil Engineering, Harbin Institute of Technology, Harbin 150090, China 2 Key Lab of Structures Dynamic Behavior and Control of the Ministry of Education, Harbin Institute of Technology, Harbin 150090, China 3Key Lab of Smart Prevention and Mitigation of Civil Engineering Disasters of the Ministry of Industry and Information Technology, Harbin Institute of Technology, Harbin 150090, China
School of Civil Engineering, Harbin Institute of Technology, Harbin 150090, China
Published
2019-05-10
Section
CONSTRUCTION MATERIALS