Session 14 : Construction Chemicals
Chair: Fedinand Leopolder, Drymix, DEImproved protection of architectural structures, environmental friendliness, energy saving, easier and quicker application and enhanced design properties are the key words that drive the construction chemicals business. This session presents recent progress in raw materials, concrete, mortar and cement formulations focusing flooring systems, structure-property relationships as well as physico-chemistry properties.
| << Previous Session | Next Session >> |
Tuesday Afternoon 14.00 – 17.30 h
Room Kopenhagen
14.1 14.00 – 14.30 h Chromate reducers for the mortar industry Dr. Dieter Guhl, TIB Chemicals, DE The reduction of Chromium(VI) is obligatorial not only for the cement manufacturers but also for all producers of cement based products since the EU has set a regulation n force, which limits the content of soluble Cr(VI) to max. 2 ppm in cements. For the mortar industry this is a special challenge, because the efforts of the cement industry are in many cases not sufficient for the special requirements of the dry mix industry. Key issues for the use of chromate reducers are: - Analysis of Cr(VI) in cement based admixtures - Influence of the Chromate Reducers on the performance of the cement based products - Long term stability of the reduction effect. The paper will deal with these issues and show which effects can be achieved by chromate reducers based on stannous sulphate and how the tin(II) technology responds to the technical challenges.  | ||
| 14.2 14.30 – 15.00 h Polyglykol methacrylates – new monomers for concrete superplasticizers Oliver Mogck, Clariant Produkte, DE The invention of concrete plasticizers in 1962 was a quantum leap in modern concrete technology. In concrete production, the use of admixtures to manage and adjust the properties of the fresh and the cured concrete is nowadays state of the art. Today, about 45% of all superplasticizers used are based on the PCE (polycarboxylate ethers) technology. Currently many PCEs are based on macromomoners derived from polyethylene glycol monomethylethers (M-PEGs) by esterification with e.g. methacrylic acid. Subsequent copolymerization leads to PCE superplasticizer polymers. A new generation of macromonomers for PCEs is available by direct alkoxylation of methacrylic acid derivatives. With this new approach a broad range of PCE precursors can be offered without the costly esterfication step. By adjusting the polyethylene glycol chain length the properties of the final PCE can be tailored. Results from cement lime experiments, showing the basic structure-property-relations, will be presented. | ||
| 14.3 15.00 – 15.30 h Advantages of ethacryl technology on the concrete formulations Dr. David Platel, Coatex, FR The implementation of cement materials is improved by addition of polymer as called superplasticizer. In this presentation, we look for the impact of the polymer architecture on the physico-chemistry properties of cement slurries. At first, we focus on the adsorption of these sodium polymethacrylate grafted by poly(ethylene oxide) chains on different types of cement using macroscopic and microscopic techniques. Then, we measure the setting time, the behavior at rest and the fluidity of different cement slurries with the use of new tools such as the helicoidal ribbon geometry and the ultrasound technique. Finally, we present the advantages of Ethacryl technology on the concrete formulations. 15.30 – 16.00 h Networking: Refreshments & Coffee Break | ||
| 14.4 16.00 – 16.30 h High wear resistant solution for flooring systems based on a specific combination of calcium aluminate cement and calcium aluminate as reactive filler Jacques Estival, Kerneos Research Center, FR Calcium Aluminate is a polyvalent hydraulic binder which is commonly used either alone or in combination with Calcium Sulphate source and/or Portland cement in a wide range of building chemistry applications. Less well known are the combinations of Calcium Aluminate cement and reactive fillers of the same chemical nature as well as their exceptional mechanical properties. This paper reports formation and microstructure development of Calcium Aluminate cement and Calcium Aluminate filler based system under various conditions of hydration. The structure/properties link is examined and compared to classical formulated systems. The addition of mineral components as slag, fume silica to this specific hydraulic binder has also been investigated. Due to its specific set of hydrates and to the developed microstructure, this material exhibits higher performances than classical systems in terms of wear resistance, surface hardness and mechanical properties. Therefore, it is a solution of choice for flooring systems which require high demanding properties. | ||
| 14.5 16.30 – 17.00 h An original, highly redispersible powdery water repellent for cement based materials Dr. Mustapha Sari, Hexion Speciality Chemicals, FR Water ingress is a key issue for durable performances in cement based materials: it is well known that moisture leads to degradation of the mechanical performances, but also of the original aesthetics (due to dirt pick-up, discoloration, efflorescence, fungal and algal proliferation) especially in coloured grouts and decorative renders. Most conventional water repellents present quite serious problems, linked to their intrinsic hydrophobicity: in addition to the mixing problem with the fresh cementitious material, they often tend to migrate towards the air-dried surface, leading to a heterogeneous material with irregular performances and a limited durability. A new kind of water repellent was developed, based on an innovative concept making hydrophobic species dispersible in aqueous media. The resulting dry emulsion can then be easily redispersed in cementitious materials, giving a real advantage in terms of mixing capability, during the gauging phase. In this paper are discussed the enhanced water proofing properties exhibited by some cement based composites after addition of this new hydrophobing agent: the latter provides an efficient and homogenous damp proofing of their surface and bulk, with improved colour preservation. Contact angle measurements and capillary water absorption tests were used to evaluate the water proofing properties, with a tentative correlation with the porous repartition. We show, in addition, the limited impact of the new water repellent on the cement hydration dynamics. Furthermore, a positive impact was observed regarding the fresh pastes? consistency (especially in combination with some selected vinyl ter polymers), that we studied by rheology. Key words: Water repellent, dry emulsion, redispersible powder, water absorption, composite mortar. | ||
| 14.6 17.00 – 17.30 h Impregnated textile reinforcements for concrete applications Jens Schoene, RWTH Aachen University, DE The combination of a concrete matrix reinforced by textile structures is investigated for several years now. Lighter, thinner and more filigree components can be realized, because of the reduced minimum thickness of the concrete compared to steel reinforcements. The manufacturing of demonstrators and new buildings of the RWTH Aachen University shows the implementation of these research results. However, all realized textile reinforced structures based on impregnated textiles are plane. The load bearing behaviour of textile reinforced concrete is determined by the composite behaviour of the textile reinforcement and the concrete matrix. A full penetration of the yarn cross-section with a coating compound is the condition precedent to activate all filaments and to obtain an optimized bearing strength of the compound. Furthermore the coating compound protects the fiber permanently against the alkalinity of the concrete. The Institut fuer Textiltechnik of the RWTH Aachen University (ITA) has manufactured different clutch textiles with AR-glass and carbon fibres. Their potential as textile reinforcements for concrete applications has been investigated. Aside the Welding and Joining Institute of the RWTH Aachen University (ISF) investigated and valuated different coating systems for the AR-glass reinforcements. The results show that the coating of AR-glass rovings with high modulus polymers resins can achieve the highest tensile strength and tensile tension results. Industrial tests for the industrial realization of the coating process show challenges in the textile draft of the clutch prior the curing process. Textile reinforcements with heavy drafts lead to rejections, because the calculated reinforcement directions can not be achieved. Furthermore, direction changes and the take-up process of radiuses of more than 200 mm after the curing process can cause the break of single filaments up to the entire roving. ISF and ITA identified the prepreg technology as an alternative coating process for textile reinforcements. Thus, a wide field of application with complex shapes can be taped. The needed coating technology as well as the curing mechanisms are investigated and valuated for an industrial realization by the ISF and the ITA. | ||
| << Previous Session | Next Session >> |