Effect of different water reducing agents on mechanical properties and micro-mechanism of modified hemihydrate phosphogypsum cementitious materials

IF 7.4 1区工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY

Construction and Building Materials Pub Date : 2024-11-30 DOI:10.1016/j.conbuildmat.2024.139390

Qin Wu , Qijun Long , Jia Tao , Huagang Zhang , Chuanxiang Chen , Jianxiang Wang , Fang Yu

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引用次数: 0

Abstract

The stockpiling of industrial by-product phosphogypsum causes pollution to the environment, and its effective utilization can be achieved by using cementitious materials from undisturbed hemihydrate phosphogypsum (UHPG) obtained by hemihydrate-wet process. This study investigated the creation of modified hemihydrate phosphogypsum mixture by proportionally blending quicklime with UHPG. Modified hemihydrate phosphogypsum cementitious material (MPGCM) was then prepared using melamine superplasticizer (SM) or naphthalene superplasticizer (FDN). The effects of these water reducing agents on the mechanical properties and micro-mechanisms of MPGCM were evaluated by single-factor experimental method. The results showed that both SM and FDN were effective in reducing water consumption and enhancing the fluidity of MPGCM. Additionally, both superplasticizers delayed the establishment of the MPGCM, with FDN showing a stronger retarding effect than SM. Compared with those mixed with FDN, the specimens mixed with SM exhibited markedly greater flexural and compressive strengths. The specimens with 2 % SM content achieved the highest 28 d flexural strength and compressive strength, measuring 16.61 MPa and 42.26 MPa. Microscopic analysis revealed that the water reducing agent can not only inhibit the disaggregation and dissolution of calcium sulfate hemihydrate and the crystallization of calcium sulfate dihydrate, but also promote the transformation of calcium sulfate dihydrate crystals from long rods to short columns or plates, so that the reticular structure is more compact and the mechanical strength is improved. This study suggests that the optimal composition, consisting of 97 % UHPG, 3 % quicklime, and 2 % SM, yields the optimum mechanical properties. These results provide a theoretical foundation for the application of phosphogypsum in practical engineering and support the sustainable development of phosphorus chemical industries.

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来源期刊

Construction and Building Materials 工程技术-材料科学：综合

CiteScore

13.80

自引率

21.60%

发文量

3632

审稿时长

82 days

期刊介绍： Construction and Building Materials offers an international platform for sharing innovative and original research and development in the realm of construction and building materials, along with their practical applications in new projects and repair practices. The journal publishes a diverse array of pioneering research and application papers, detailing laboratory investigations and, to a limited extent, numerical analyses or reports on full-scale projects. Multi-part papers are discouraged. Additionally, Construction and Building Materials features comprehensive case studies and insightful review articles that contribute to new insights in the field. Our focus is on papers related to construction materials, excluding those on structural engineering, geotechnics, and unbound highway layers. Covered materials and technologies encompass cement, concrete reinforcement, bricks and mortars, additives, corrosion technology, ceramics, timber, steel, polymers, glass fibers, recycled materials, bamboo, rammed earth, non-conventional building materials, bituminous materials, and applications in railway materials.