Filtern
Dokumenttyp
Sprache
- Englisch (4)
Referierte Publikation
- ja (4)
Schlagworte
- Artificial weathering (2)
- Stearates (2)
- Water repellent admixtures (2)
- Water-repellent admixtures (2)
- Hydration (1)
- Hydration products (1)
- Mortars (1)
- Natural hydraulic lime (1)
- Pore size distribution (1)
- Portland limestone cement (1)
- Portland limestone cement mortars (1)
- Pozzolana-lime (1)
- Pozzolana-lime mortars (1)
- Restoration (1)
- Restoration mortars (1)
- Salt crystallization (1)
- Silane (1)
- Siloxanes (1)
- Water absorption (1)
Pozzolanalime mortars modified with water-repellent admixtures were designed and studied to obtain mortars for restoration application. Powdered silane and calcium stearates were mixed with pozzolana, lime and sand and the chemicalphysical properties of the resulting mortars were evaluated by X-ray diffraction, electron microscopy (SEM-EDX), thermogravimetric analysis and FT-IR spectroscopy. The mechanical behavior, the pore structure and the hygric behavior were measured. The resistance of water-repellent mortars to the salt crystallization was evaluated. Both calcium stearates and powdered silane allowed good water-repellent protection even if the water-repellent agents and their dosage modified some physical properties and the hydration kinetic.
Water-repellent renders were studied in order to evaluate their suitability for restoration applications. Water repellent admixtures, such as powdered siloxane-based products and metal soaps (zinc and calcium stearates), were mixed with a pozzolana-lime binder similar to historical binders with hydraulic properties. The chemical-physical and structural properties, the effectiveness and the durability of the water-repellent mortars in different environmental conditions were studied. The influence of the water repellent admixtures was evaluated by FT-IR analyses, by testing the mechanical properties and the behaviour in presence of water. The durability of the water-repellent mortars was evaluated after the exposure to artificial weathering (UV-light and water) and to immersion/drying cycles in saturated sodium sulphate solution. The nature of the water-repellent admixtures influenced both the hydration reactions and the chemical-physical properties of the mortars resulting in different resistance to the weathering and to salt crystallization.
The study evaluates Portland limestone cement mortars, natural hydraulic lime mortars and pozzolan-lime mortars modified with water-repellent admixtures (metal soaps and siloxanes) for their use in the maintenance of historic buildings. The chemical-physical characteristics, the durability and the resistance to artificial weathering (exposure to UV light and artificial rain) were examined. The exposure conditions used in the ageing test were chosen in order to simulate outdoor environmental conditions, in particular the processes caused by UV-light and thermal shock induced by rain water.
Water-repellent mortars were prepared using different hydrophobic compounds as admixtures. Calcium and zinc stearates, silane/siloxane products (as liquid solution and powder) were mixed into limestone cement mortars for obtaining in-bulk water-repellent mortars suitable for building protection and resistant to the degrading action of water. The influences of the admixtures on the hydration and structure of the designed mortars were investigated by SEM, TG–DSC, FT-IR, XRD, and isothermal calorimetry. The effectiveness of these agents against water action was evaluated by using techniques and methods such as mercury intrusion porosimetry, water absorption tests and contact angle measurements. Siloxane products conveyed good water-repellent effectiveness, without strongly influencing the setting and hydration of the binder, while the zinc stearates slowed down the hydration reactions.