A platform for research: civil engineering, architecture and urbanism
A platform for research: civil engineering, architecture and urbanism
Biogener Säureangriff auf Betone im Biogasanlagenbau: Schädigungsmechanismen sowie Entwicklungspotentiale
Actually, limited experiences concerning possible damage processes in biogas plants exist. This is based on the young history of development, the difficult accessibility and the large variance of procedures. Thus, damaged constructions as well as embedded material samples were analyzed under the consideration of the plant specific procedure conditions. During the process of ensiling, organic acids are formed in pre-storage containers (similar to silo constructions). These organic acids can reach pH-values < 3.5 due to improperly ensiling. This results in the hydrolysis of the phases in the hardened cement matrix in cases of inadequate protection measures. The primarily originating Ga-salts have a high solubility and will be rapidly dissolved. Compared to pure H2SO4-a.tta.ck, the damaged zone is characterized by a comparatively low ablation and by a large reaction zone. Within single-stage fermenters, during the process of internal desulphurization by the entering of atmospheric oxygen, biogenic S followed by H2SO4 and SO42- is formed within the gas phase on the material surface by condensation. The biogenic attack is benefitted due to the formation of carbonic acid. Within multi-stage fermenters, organic acids within the liquid phase can also damage the concrete (necessary exposure classes "XA2" according EN 206-1). During the process of internal desulphurization by iron chlorides, the limit values for a chloride-induced steel corrosion can be exceeded. Within fermentation residue deposits, no significantly chemical attack is assumed. The mode of action of the acid-types and the influence of different testing conditions such as saturation, temperature as well as fluid dynamic of the test solution or the abrasion could be analyzed by small and large full-scale laboratory tests. On this basis, samples were stressed by accelerated test procedure. The porosity and the solubility of the originating phases in the hardened cement could be decreased by the variation of the cement-type, the concrete admixtures and the water as well as binder content under compliance of the normative regulations. Increased damage was measured by high-alumina cement. Concrete with supersulfated cements showed a similar performance as concretes with blast furnace slag concrete. Despite increased capillary porosity and slower strength development, the significantly highest acid resistance could be generated using CaO-poor alkali-activated binders. Silica-rich systems clarify, that the degree of damage can be quantified by the depth of damage and not by the sample mass.
Biogener Säureangriff auf Betone im Biogasanlagenbau: Schädigungsmechanismen sowie Entwicklungspotentiale
Actually, limited experiences concerning possible damage processes in biogas plants exist. This is based on the young history of development, the difficult accessibility and the large variance of procedures. Thus, damaged constructions as well as embedded material samples were analyzed under the consideration of the plant specific procedure conditions. During the process of ensiling, organic acids are formed in pre-storage containers (similar to silo constructions). These organic acids can reach pH-values < 3.5 due to improperly ensiling. This results in the hydrolysis of the phases in the hardened cement matrix in cases of inadequate protection measures. The primarily originating Ga-salts have a high solubility and will be rapidly dissolved. Compared to pure H2SO4-a.tta.ck, the damaged zone is characterized by a comparatively low ablation and by a large reaction zone. Within single-stage fermenters, during the process of internal desulphurization by the entering of atmospheric oxygen, biogenic S followed by H2SO4 and SO42- is formed within the gas phase on the material surface by condensation. The biogenic attack is benefitted due to the formation of carbonic acid. Within multi-stage fermenters, organic acids within the liquid phase can also damage the concrete (necessary exposure classes "XA2" according EN 206-1). During the process of internal desulphurization by iron chlorides, the limit values for a chloride-induced steel corrosion can be exceeded. Within fermentation residue deposits, no significantly chemical attack is assumed. The mode of action of the acid-types and the influence of different testing conditions such as saturation, temperature as well as fluid dynamic of the test solution or the abrasion could be analyzed by small and large full-scale laboratory tests. On this basis, samples were stressed by accelerated test procedure. The porosity and the solubility of the originating phases in the hardened cement could be decreased by the variation of the cement-type, the concrete admixtures and the water as well as binder content under compliance of the normative regulations. Increased damage was measured by high-alumina cement. Concrete with supersulfated cements showed a similar performance as concretes with blast furnace slag concrete. Despite increased capillary porosity and slower strength development, the significantly highest acid resistance could be generated using CaO-poor alkali-activated binders. Silica-rich systems clarify, that the degree of damage can be quantified by the depth of damage and not by the sample mass.
Biogener Säureangriff auf Betone im Biogasanlagenbau: Schädigungsmechanismen sowie Entwicklungspotentiale
König, Andreas (author)
2013
314 Seiten, 178 Bilder, 63 Tabellen, 324 Quellen
Theses
German
Betone für biogenen Säureangriff im Landwirtschaftsbau
Online Contents | 2010
Betone für biogenen Säureangriff im Landwirtschaftsbau
| Wiley | 2010