Historic trass - lime mortars with expansive reactions: Characterization and repair strategies

The characterisation of two ancient mortars in historic bridges, suffering damage due to thaumasite and other swelling compounds is described. Characterisation was part of the analysis of damage occurring to the brick masonry structure. Expansive reactions were found to have taken place, being the cause of the damage to the masonry. In both...

Vuil en alg op pleisterwerk. TNO ontwikkelt beoordelingsmethode

Onderzoek naar vervuilingsgraad van pleistersystemen

Onderhoud van gepleisterde gevels wordt een steeds belangrijker aandachtspunt bij het nemen van ontwerpbeslissingen en zou beter dan nu voorzienbaar en budgetteerbaar moeten zijn. Om met het oog op toekomstig onderhoud in het ontwerpstadium reeds kwaliteitsverschillen van pleistersystemen te kunnen inschatten, heeft TNO meetmethoden ontwikkeld

Experimental research on hygroscopic behaviour of porous specimens contaminated with salts

Salt crystallisation is one of the main causes of masonry decay in monuments. The salt content in a wall is a very important parameter that should be known in order to give a reliable diagnosis on the causes of damage; if a restoration work and a surface treatment are necessary, the salt content has to be known. In fact the presence of salts in...

Hydrofoberen van windmolens. Effectieve behandeling of vragen om ellende

Salinization effects on the water sorption of porous building materials

The interaction of salt transport and moisture transport plays a crucial role in some deterioration mechanisms of porous building materials. For this reason it has been an important research subject for mant' years. Yet most research was still complicated by the lack of experimental techniques capable of measuring., salt content. Therefore TNO...

Composition of mortar as a function of distance to the brick-mortar interface: A study on the formation of cured mortar structure in masonry using NMR, PFM and XRD

The formation of cured mortar structure in masonry was studied using multiple experimental techniques. Starting with fresh mortar, nuclear magnetic resonance (NMR) was used to measure the water extraction during brick laying. After curing, the composition of cured mortar was investigated with polarizing and fluorescent microscopy (PFM) and X-Ray...

Moisture transport in brick masonry - the grey area between bricks

Water extraction out of mortar during brick laying: A NMR study

The water extraction out of mortar during brick laying was studied using nuclear magnetic resonance. The experiments show that using a fired-clay brick, the water is extracted out of the mortar within 3 minutes, whereas in the case of a sand-lime brick this takes about 10 minutes. Prewetting a fired-clay brick hardly affects the water extraction...

Moisture transport properties of mortar and mortar joint: A NMR study

The moisture transport in mortar and mortar joint often is an important parameter in degeneration of brick masonry and other block constructions. In this study, the influence of single additives on the moisture transport properties of mortar is investigated. Due to water extraction during brick laying, curing conditions of mortar in mortar joint...

Water absorption in brick masonry

The water absorption in brick, mortar that was cured separately, and masonry samples was studied using NMR. Models of the moisture transport are usually formulated on the basis of a diffusion equation. In the case of water absorption in separate brick and mortar samples, the moisture diffusivity in this equation can be approximated by an...

Moisture transport over the brick-mortar interfaces

Water extraction out of mortar during brick laying. An NMR study

The water extraction out of mortar during brick laying was studied by nuclear magnetic resonance. The water extraction is an important parameter that determines, e.g., the stiffness of the mortar due to compaction of the cement particles and the bond strength of the cured-mortar interfaces but allo the hygric properties of the mortar joints....