期刊
CONSTRUCTION AND BUILDING MATERIALS
卷 73, 期 -, 页码 222-228出版社
ELSEVIER SCI LTD
DOI: 10.1016/j.conbuildmat.2014.09.075
关键词
Phosphogypsum; Non-fired bricks; Two-step Hydration Process; Waste recycling; Construction materials
资金
- National Natural Science Foundation of China [41002124]
- Hubei Environmental Protection Bureau [2013HB10]
Phosphogypsum (PG) is a solid waste mainly containing calcium sulfate dihydrate (CaSO4 center dot 2H(2)O). Preparing the non-fired wall bricks/blocks from PG is a prospective strategy for utilizing the waste. However, there are several shortages in the current technologies of PG brick production, such as, indispensable using of cement, high pressure in press-forming, high energy consumption in autoclaving curing, and/or poor mechanical properties of bricks. This study proposes a novel Two-step Hydration Process for preparing PG non-fired bricks of a high 7-day compressive strength of 29 MPa, using no cement and a low pressure of 10 MPa in press-forming. The optimal formulation comprises 75.0% of PG, 23.47% of river sand and 1.53% of hydrated lime, and the water incorporation is 22% of all the above solids. The corresponding water absorption, weight loss and compressive strength after 15 freezing thawing cycles of as-prepared 7-day bricks are 10.19%, 1.1% and 23 MPa, respectively, which fully meet the quality requirements of the highest MU25 grade in the Chinese standard (JC/T422-2007). This creative process has the potential to cost-effectively recycle the waste PG and solve its environmental pollution. (C) 2014 Elsevier Ltd. All rights reserved.
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