کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
1457381 989258 2010 10 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Modeling the degradation of Portland cement pastes by biogenic organic acids
موضوعات مرتبط
مهندسی و علوم پایه سایر رشته های مهندسی مهندسی صنعتی و تولید
پیش نمایش صفحه اول مقاله
Modeling the degradation of Portland cement pastes by biogenic organic acids
چکیده انگلیسی

Reactive transport models can be used to assess the long-term performance of cement-based materials subjected to biodegradation. A bioleaching test (with Aspergillus niger fungi) applied to ordinary Portland cement pastes during 15 months is modeled with HYTEC. Modeling indicates that the biogenic organic acids (acetic, butyric, lactic and oxalic) strongly accelerate hydrate dissolution by acidic hydrolysis whilst their complexation of aluminum has an effect on the secondary gel stability only. The deepest degradation front corresponds to portlandite dissolution and decalcification of calcium silicate hydrates. A complex pattern of sulfate phases dissolution and precipitation takes place in an intermediate zone. The outermost degraded zone consists of alumina and silica gels. The modeling accurateness of calcium leaching, pH evolution and degradation thickness is consistently enhanced whilst considering increase of diffusivity in the degraded zones. Precipitation of calcium oxalate is predicted by modeling but was hindered in the bioleaching reactor.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Cement and Concrete Research - Volume 40, Issue 8, August 2010, Pages 1165–1174
نویسندگان
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