@inproceedings{HuengerKositzHuengeretal., author = {H{\"u}nger, Klaus-J{\"u}rgen and Kositz, Mario and H{\"u}nger, Maximilian and Krey, Juliane and M{\"u}hlst{\"a}dt, Mike}, title = {Surface coating of siliceous parts of aggregate grains by alumina containing SCM' in alkaline solutions}, series = {ICAAR, 15th International Conference on Alkali Aggregate Reaction, July 03-07, 2016, Sao Paulo, Brazil, abstracts}, booktitle = {ICAAR, 15th International Conference on Alkali Aggregate Reaction, July 03-07, 2016, Sao Paulo, Brazil, abstracts}, publisher = {ICAAR}, pages = {S. 42}, abstract = {It is well known that SCMs containing alumina can prevent the damaging alkali silica reaction in concrete. This paper deals with the direct interactions between aggregate grain surfaces (quartzitic rock material Q1) and the dissolved amounts of SCMs (metakaolin, aluminum hydroxide). Investigations have confirmed that the presence of such SCMs can strongly decrease the silica release from aggregates in comparison to solubility experiments without SCM addition. The reason for this effect is the formation of a thin alumina containing layer (some nanometers thick) on the grain surfaces. The existence of this layer could be determined by XPS. Only this method provides data of the strongly increased alumina concentration in a thin surface area and also of the layer thickness in dependence on reaction parameters. Dissolution experiments of grains coated with such layer demonstrate the effectiveness of this process and can give a further contribution for understanding the preventing mechanisms of SCMs.}, language = {en} } @inproceedings{GroeschkeUhlmannHuengeretal., author = {Gr{\"o}schke, Andreas and Uhlmann, Wilfried and H{\"u}nger, Klaus-J{\"u}rgen and Wiehe, Wolfgang and Beckmann, T.}, title = {Spezielle Untersuchungen zur Mineralogie in unges{\"a}ttigten Kippenmassiven}, series = {Vortragsband des 4. GBL-Kolloquiums vom 26. - 28. November 1997 in Cottbus, Ergebnisse und Empfehlungen}, booktitle = {Vortragsband des 4. GBL-Kolloquiums vom 26. - 28. November 1997 in Cottbus, Ergebnisse und Empfehlungen}, publisher = {Schweizerbart}, address = {Stuttgart}, isbn = {3-510-95822-5}, pages = {57 -- 63}, language = {de} } @misc{HuengerHuebertScholz, author = {H{\"u}nger, Klaus-J{\"u}rgen and H{\"u}bert, Cornelia and Scholz, Yvonne}, title = {Drum pr{\"u}fe, was sich ewig bindet … - zur Vertr{\"a}glichkeit der Betonausgangsstoffe}, series = {BFT Betonwerk + Fertigteil-Technik}, volume = {75}, journal = {BFT Betonwerk + Fertigteil-Technik}, number = {3}, issn = {1865-6528}, pages = {46 -- 55}, language = {de} } @misc{BachmannHuenger, author = {Bachmann, Robert and H{\"u}nger, Klaus-J{\"u}rgen}, title = {BTU-SP-Schnelltest zur Beurteilung der Alkaliempfindlichkeit von Gesteinsk{\"o}rnungen : die Entwicklung eines direkten Pr{\"u}fverfahrens}, series = {Beton}, volume = {59}, journal = {Beton}, number = {4}, issn = {0005-9846}, pages = {138 -- 143}, language = {de} } @misc{Huenger, author = {H{\"u}nger, Klaus-J{\"u}rgen}, title = {Der BTU-SP-Test: Direktes Pr{\"u}fverfahren zur Bewertung der Alkali-Empfindlichkeit von Gesteinsk{\"o}rnungen}, series = {Straße und Autobahn}, volume = {61}, journal = {Straße und Autobahn}, number = {3}, issn = {0039-2162}, pages = {143 -- 147}, language = {de} } @misc{KrakowHuengerBrigzinsky, author = {Krakow, Lutz and H{\"u}nger, Klaus-J{\"u}rgen and Brigzinsky, Maria}, title = {Projekt ALEKOM - Aschegebundenes Ton-/Lehmfeinkornsystem}, series = {Ceramic forum international : cfi, Berichte der Deutschen Keramischen Gesellschaft}, volume = {87}, journal = {Ceramic forum international : cfi, Berichte der Deutschen Keramischen Gesellschaft}, isbn = {0173-9913}, pages = {D8 -- D10}, language = {de} } @misc{HuengerHill, author = {H{\"u}nger, Klaus-J{\"u}rgen and Hill, Steffen}, title = {Direct assessment of the alkali sensitivity of precambrian greywackes}, series = {Cement International}, volume = {3}, journal = {Cement International}, number = {1}, issn = {1610-6199}, pages = {104 -- 119}, language = {en} } @misc{HuengerHill, author = {H{\"u}nger, Klaus-J{\"u}rgen and Hill, Steffen}, title = {Chemischer Schnelltest zur praxiskonformen Pr{\"u}fung der Alkaliempfindlichkeit von Gesteinsk{\"o}rnungen f{\"u}r Beton}, series = {BFT Betonwerk + Fertigteil-Technik}, volume = {71}, journal = {BFT Betonwerk + Fertigteil-Technik}, number = {7}, issn = {0373-4331}, pages = {36 -- 47}, language = {de} } @misc{HillHuenger, author = {Hill, Steffen and H{\"u}nger, Klaus-J{\"u}rgen}, title = {Alkaliempfindlichkeit Lausitzer Grauwacken - neue Perspektiven hinsichtlich eines direkten Pr{\"u}fverfahrens}, series = {Forum der Forschung}, volume = {8}, journal = {Forum der Forschung}, number = {17}, issn = {0947-6989}, pages = {122 -- 127}, language = {de} } @phdthesis{Huenger, author = {H{\"u}nger, Klaus-J{\"u}rgen}, title = {Zum Reaktionsmechanismus pr{\"a}kambrischer Grauwacken aus der Lausitz bei ihrer Verwendung als Gesteinsk{\"o}rnung im Beton}, publisher = {Shaker-Verlag}, address = {Aachen}, isbn = {3-8322-4670-3}, pages = {IX, 235, A - I}, language = {de} } @misc{Huenger, author = {H{\"u}nger, Klaus-J{\"u}rgen}, title = {The Contribution of Quartz and the Role of Aluminum for Understanding the AAR with Greywackes}, series = {Cement and concrete research}, volume = {37}, journal = {Cement and concrete research}, number = {8}, issn = {0008-8846}, pages = {1193 -- 1205}, language = {en} } @misc{BachmannHuengerScholz, author = {Bachmann, Robert and H{\"u}nger, Klaus-J{\"u}rgen and Scholz, Yvonne}, title = {Entwicklung eines direkten Pr{\"u}fverfahrens zur Alkaliempfindlichkeitsbeurteilung von Gesteinsk{\"o}rnungen : der BTU-SP-Schnelltest}, series = {Forum der Forschung}, journal = {Forum der Forschung}, number = {20}, issn = {0947-6989}, pages = {73 -- 78}, language = {de} } @inproceedings{ScholzHuebertHuenger, author = {Scholz, Yvonne and H{\"u}bert, Cornelia and H{\"u}nger, Klaus-J{\"u}rgen}, title = {The influence of supplementary cementing materials on the dissolution of aggregates in alkaline solutions}, series = {ICAAR, 15th International Conference on Alkali Aggregate Reaction, July 03-07, 2016, Sao Paulo, Brazil, abstracts}, booktitle = {ICAAR, 15th International Conference on Alkali Aggregate Reaction, July 03-07, 2016, Sao Paulo, Brazil, abstracts}, publisher = {ICAAR}, pages = {S. 43}, abstract = {Starting from expansion measurements on concrete prisms, produced with two different alkali reactive aggregates, the influence of two aluminium containing SCMs on the expansion of concrete prisms and on the solubility of the aggregates in an alkaline solution were investigated. The solubility of aggregates in an alkaline solution reflects the alkali reactivity of the corresponding aggregate. Initially, the solubility experiments with the aggregates and SCMs were made separately and then in mixtures of each aggregate and SCM. In a further step, the SCMs were stored in KOH solutions containing Ca(OH)2. The concentrations of SiO2 and Al2O3 were determined to investigate the effect of calcium on the solving processes of SCMs. The combination of concrete expansion test and dissolution experiments of two alkali reactive aggregates and two aluminium containing SCMs allows first conclusions about the influence of such SCMs on the reactivity of aggregates.}, language = {en} } @inproceedings{HuengerHuebertScholzetal., author = {H{\"u}nger, Klaus-J{\"u}rgen and H{\"u}bert, Cornelia and Scholz, Yvonne and Kronemann, Jens}, title = {Changes of pore solution composition under accelerated mortar bar and concrete prism test conditions}, series = {ICAAR, 14th International Conference on Alkali Aggregate Reaction, May 20-25, 2012, Austin, TX}, booktitle = {ICAAR, 14th International Conference on Alkali Aggregate Reaction, May 20-25, 2012, Austin, TX}, pages = {10}, abstract = {Accelerated tests of mortar bars and concrete prism were carried out at temperatures ≥ 40°C in order to reduce the test duration. Because the OH-/SO42- equilibrium is shifted to lower values with increasing temperature and alkali content of the cement, there exists the possibility of side reactions between sulphate ions from the cement and aluminate ions which can come from mineral admixtures and aggregates. Solubility measurements of two types of aggregates in sulphate free KOH solutions indicate that the temperature effect on the silica releasing rate is bigger than the inhibiting effect of the decreasing OH- concentration. To avoid side reactions during aggregate test procedure, expansion measurements should be performed at 40°C in combination with adapted solubility measurements.}, language = {en} } @inproceedings{BrigzinskyHuenger, author = {Brigzinsky, Maria and H{\"u}nger, Klaus-J{\"u}rgen}, title = {Durable Extruded and Self-Hardening Loam Bricks Based on Fly Ash from Lignite}, series = {Proceedings, 23rd Czech Concrete Day 2016}, booktitle = {Proceedings, 23rd Czech Concrete Day 2016}, isbn = {978-80-906097-6-1}, pages = {6}, abstract = {The basis of the primary energy supply in the Czech Republic is mainly lignite combustion. Power plants are for example Chvaletice, Melnik, Pocerady, Porici, Prunerov, Ledvice, Tusimice, Tisova and Hodonin [1,2]. Accordingly, there is a large amount of fly ash with its latent hydraulic and puzzolanic properties, depending on the composition. In terms of sustainability, such industrial residues offer huge potential for conversation of resources and often connected with it, a CO2-reduction. Especially lime-rich fly ashes offer a variety of possibilities in the high quality production of self-hardening loam-bricks, having an improved durability. Different clays/loams were mixed with fly ashes (10 to 30 wt-\%) and homogenized by addition of water. Out of these mixtures, samples were moulded in different dimensions by using an extruding press. After curing under different humidity conditions at room temperature, the samples were tested for their strength and their durability. The investigations showed, that the choice of the starting materials has significant impact to the workability and the development of the strength. Furthermore, there is an optimal amount for the ash in the recipes to prevent a rapid destruction by capillary water absorption. The modified clay bricks could make a decisive contribution to the improvement of weather resistance e.g. in tropical areas with sudden rain showers.}, language = {en} } @inproceedings{HuengerHuebertScholz, author = {H{\"u}nger, Klaus-J{\"u}rgen and H{\"u}bert, Cornelia and Scholz, Yvonne}, title = {On the Interactions of Aggregates with Supplementary Cementing Materials for Durable Concrete Structures}, series = {Proceedings, 23rd Czech Concrete Day 2016}, booktitle = {Proceedings, 23rd Czech Concrete Day 2016}, isbn = {978-80-906097-6-1}, pages = {7}, abstract = {Supplementary cementing materials (SCMs) are an important part of modern concrete structures. Their use has many advantages (reduction of the cement amount, improvement of the durability and therefore CO2 reduction). For example certain SCMs added to concrete mixtures can avoid the alkali-silica reaction (ASR). But such materials have a wide range of composition and therefore the mechanisms can be very differently. The knowledge of dissolution processes of aggregates and SCMs separate and together in alkaline solutions can help to understand the damage of concretes caused by ASR and the effects to avoid ASR in more details. Many dissolution experiments were performed in highly alkaline solutions (KOH) under CPT conditions (pH 14, 40°C) using aggregates in original grain sizes and Si and Al containing SCMs in different ratios. Also Calcium hydroxide was added to investigate the influence of calcium ions as a main part of the pore solution. The concentrations of soluble silica and alumina were determined by ICP-OES. Such dissolution experiments, with which an interaction was settled between the aggregate and the SCM via the alkaline solution, arose that under specific conditions the dissolution of aggregates was strongly influenced. Obviously both main constituents of concretes interact with each other. Additionally effects of the dissolved calcium ions must be considered. It was found that the efficiency depends on the amount and chemical composition of the SCMs used and on the reactivity of aggregates.}, language = {en} } @inproceedings{BachmannHuenger, author = {Bachmann, Robert and H{\"u}nger, Klaus-J{\"u}rgen}, title = {Interactions of chemical and physical parameters of aggregate grains for a better understanding of alkalisilca-reaction}, series = {ICAAR, 14th International Conference on Alkali Aggregate Reaction, May 20-25, 2012, Austin, TX}, booktitle = {ICAAR, 14th International Conference on Alkali Aggregate Reaction, May 20-25, 2012, Austin, TX}, pages = {10}, abstract = {Mortar bar and concrete prism tests are the most commonly used methods for the evaluation of alkali-silica reactivity (ASR). Despite their widespread use, both methods have significant drawbacks. The largest issue is that neither test is a direct measurement of the aggregate. Matrix effects from the mortar or concrete, or variations in the individual non-aggregate materials can influence the outcome. This paper describes fundamental results as the basis for the chemical and physical test method (BTU-SP test) directly carried out at aggregate grains. Additional methods (BET, microscopy) confirm that not only the aluminate from the aggregate controls the silica release but also the pore structure inside of rocks (i.e. voids, cracks) buffer the swelling potential of the formed alkali-silica gel. As a result a reaction model describing the interactions of chemical and physical parameters in 4 phases has been developed for an alkalisilica reaction.}, language = {en} } @inproceedings{HuengerKronemannHuebertetal., author = {H{\"u}nger, Klaus-J{\"u}rgen and Kronemann, Jens and H{\"u}bert, Cornelia and Scholz, Yvonne}, title = {On the mechanism of ASR inhibition by Si and Al containing SCMs}, series = {13th International Conference on Recent Advances in Concrete Technology and Sustainability Issues, Ottawa, Canada}, booktitle = {13th International Conference on Recent Advances in Concrete Technology and Sustainability Issues, Ottawa, Canada}, publisher = {American Concrete Institute}, isbn = {978-1-9427272-3-1}, pages = {437 -- 451}, abstract = {The use of supplementary cementing materials (SCMs) added to concrete mixtures can avoid the alkali-silica reaction. Such materials have a wide range of composition and therefore the inhibition mechanisms can be very differently. The effectiveness of SCMs which provide silica and alumina into the alkaline solution cannot only be explained by reducing the OH--concentration of the pore solution. From dissolution experiments in potassium hydroxide solutions, an interaction was noted between the aggregate and five SCMs via the alkaline solution. Under specific conditions, no silica is released from the aggregate grains. Mineralogical investigations (XRD, SEM+EDX) of the grain surfaces confirm that quartz is the main source of silica. In the presence of alumina providing SCMs, the quartz dissolution is strongly reduced or even sometimes stopped. On surfaces of grains a very thin layer can be observed which is probably responsible for reduction or stopping of the silica dissolution and therefore for the inhibition of ASR.}, language = {en} } @inproceedings{HuengerBrigzinsky, author = {H{\"u}nger, Klaus-J{\"u}rgen and Brigzinsky, Maria}, title = {An alternative alumino-silicate binder based on the "just add water method"}, series = {ICCM, 10th ACI/RILEM International Conference on Cementitious Materials and Alternative Binders for Sustainable Concrete, 2017, Montreal, Kanada}, booktitle = {ICCM, 10th ACI/RILEM International Conference on Cementitious Materials and Alternative Binders for Sustainable Concrete, 2017, Montreal, Kanada}, publisher = {RILEM}, pages = {14}, abstract = {Alumino silicate compounds are important for alternative binders for concretes because of the reduction of CO2 and resource conservation. Such multi-phase systems consist of a solid component, such as e.g. slag, ash, calcined clays and others, and a liquid component, in generally highly concentrated alkaline solutions (water glass or NaOH/KOH). Because of safety and other reasons, such systems exclude large-scale practical applications. The newly developed alternative binder consists of a highly soluble silicate waste material, which is not common in geopolymere production, and a powdered Al-provider. It is called alumino silicate network (ASN) binder. Both components can be mixed dry in different ratios. Only after addition of water, a polymerization process is induced and the formation of amorphous phases, and sometimes zeolites can be observed. Mortar bars were produced and tested for different properties. The best results regarding to workability, strength development and sustainability were obtained with a molar Si/Al ratio of 2:1 in combination with fine-grained rock filler components. Investigations on the hardening process showed, that the mechanical properties varied over a wide range. Strength reserves, a ratio between compressive and tensile strength of approx. 3 and so far good resistance against acid solutions allow the use as a binder in high performance mortar and concrete structures.}, language = {en} } @inproceedings{KositzHuenger, author = {Kositz, Mario and H{\"u}nger, Klaus-J{\"u}rgen}, title = {A predicitve model for the assessment of aggregate sensitivity to ASR}, series = {ICCM, 10th ACI/RILEM International Conference on Cementitious Materials and Alternative Binders for Sustainable Concrete, 2017, Montreal, Kanada}, booktitle = {ICCM, 10th ACI/RILEM International Conference on Cementitious Materials and Alternative Binders for Sustainable Concrete, 2017, Montreal, Kanada}, publisher = {RILEM}, pages = {14}, abstract = {Different aggregates stored in alkaline solutions have different solubility of silica and alumina. The dissolved silica reacts with water and alkalis to form an alkali silica gel, which can swell. ASR swelling can be reduced or prevented, if enough space is available for the alkali silica gel formation. This "space" is the open porosity, which can also be determined directly at the aggregate grains. Concrete specimens made with different aggregates were produced. They all were stored in a fog chamber at 104°F (40°C) and the ASR swelling was measured for one year. At the same time, the aggregates were stored in 0.1 mol KOH solution at 176°F (80°C) for 56 d only. The solubility of silica and alumina was determined continuously by ICP-OES. The obtained dissolution rates, open porosity and expansion data were compared and a reliable model for predicting the ASR sensitivity of concrete aggregates was derived.}, language = {en} }