Eine wesentliche Eigenschaft des Sichtbetons ist die Farbtongleichmäßigkeit, wie sie im Merkblatt Sichtbeton des DBV/BDZ beschrieben ist und für die einzelnen Sichtbetonklassen gefordert wird. Für ...die optischen Eigenschaften von Flächen gibt es keine neutralen Messverfahren. Farbe und Aussehen werden vom Betrachter stets subjektiv wahrgenommen und beurteilt. Abweichungen von der Farbe und ihrer Gleichmäßigkeit auf der betrachteten Fläche des Bauteils werden als störend empfunden und als Mangel gerügt. Mehrere Probeflächen vor Baubeginn und die Festlegung des Bausolls als Muster stellen eine praktische Lösung dar. Damit wird das Bausoll Sichtbeton eindeutig festgelegt. Eine Fülle von physikalischen und chemischen Einflüssen aus der Betontechnologie, aber auch die Verhältnisse bei der Herstellung führen zu Abweichungen im Farbton und der Farbtongleichmäßigkeit an Oberflächen von Sichtbeton. Das Wissen um ihre Herkunft und Hinweise zur Vermeidung helfen bei der Bauausführung.
Change of colour on architectural concrete‐surfaces
One of the main properties of architectural concrete is its colour and the uniformity over the complete concrete surface of a building. This property is described in detail in the DBV leaflet and is one of the requirements for the architectural concrete‐classes SB1–SB4.The colour and its variation respectively its uniformity cannot be measured. The human judgment based only on a visual inspection is always subjective. The change of colour and its variation on a concrete surface disturbs always the optical impression and the visual picture. It is from the construction point of view a mistake of the architectural concrete. The solution are sample‐walls made long before starting the construction work in order to give everybody the chance to see what is possible to be built under the conditions at the job site. Everybody who is involved can evaluate the results of these tests. At least one sample is chosen by the partners in charge and it represents the specified architectural concrete quality for the further construction work.
In addition to the natural variation of the concrete‐colour, which is normal and well known, a lot of further affects have been observed on concrete surfaces in the past. They are caused by different circumstances, conditions and variation of different building materials. These serious affects, which create partly an intensive change of colour on the concrete surface, are described. The knowledge of the reason and the background do helps to avoid these mistakes.
Positive and negative effects of water chlorination and aeration were examined in samples of sulphuric thermal water from rehabilitation pools. Although chlorination considerably improved the ...microbiological quality of the water, it caused various negative physical and chemical changes. Aeration caused loss of hydrogen sulphide and production of colloidal sulphur (milky turbidity), whereas chlorination developed a yellowish-reddish-brown colouring depending on chlorine dosage, and also provoked the disappearance of sulphides. It is concluded that sulphuric thermal water should not be chlorinated because of elimination, through chlorination, of therapeutically active compounds causing organoleptic changes that are subject to complaints from patients.
Ispitivani su regativni i pozitivni učinci kloriranja i aeracije vode u sumpornoj termalnoj vodi u bazenima za refiabilltaclju. Znatno poboljšanje mikrobiološke kvalitete vode zbog kloriranja vode ...dovelo je do negativnih fizikalno-kemijskih promjena vode. Zbog aeracije gubi se sumporovodik i izlučuje koloidni sumpor (mliječna mutnoća), a zbog kloriranja javlja se žuckasta, crvenkasta do smeđa obojenost ovisno o dozi klora, a također nestaju sulfidi. Kloriranje termalne sumporne vode ne bi trebalo provoditi jer se iz vode eliminiraju terapijski aktivni spojevi i dolazi do organoleptičkih promjena na koje se pacijenti žale.
