Effect of Alkali and Mineral Admixtures on Mildew and Properties of Phosphogypsum
In order to solve the shortcomings of phosphogypsum products such as easy to mold,low mechanical properties and poor water resistance,the study combined alkaline materials such as lime and calcium carbide slag,and the mineral admixtures such as mineral slag and metakaolin to improve their properties.The hydration products of phosphogypsum products were determined by scanning electron microscope,X-ray diffraction and mercury injection apparatus.The results showed that alkali could effectively inhibit the mildew of phosphogypsum products.Under alkaline conditions,mineral admixtures could improve the mechanical properties and water resistance of phosphogypsum products.When phosphogypsum was 72％,slag was 20％,metacolinite was 8％ and calcium carbide slag was 5％,phosphogypsum products had the best performances,the compressive strength was 23.19 MPa,water absorption was 27％,and softening coefficient was 0.85.Calcium silicate hydrate(C-S-H)was superior to ettringite for pore structure optimization.
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