Historical Brick Masonry Research Articles

Characterisation Of Mechanical Properties OfHistoric Mortars – Testing Of Irregular Samples

The design of new renders and repair mortars requires a certain knowledge about the mechanical properties of historic materials. The common problem is that the extracted samples of historic mortars often have an irregular shape not suitable for standardised physical and mechanical laboratory tests. This is for example a problem with the testing of bedding mortars from historic brick masonry and/or renders where a typical sample width is around 10–15mm. Typical samples from wall cores are mortar bulks of very irregular shapes. In addition to the various non-standard sizes and shapes there is often a need for minimum intervention which leads to minimalisation of samples in numbers and sizes. The experimental part describes testing of specimens made of irregular samples of historic and modern mortars in compression and bending. The key problem was obtaining a certain measurable shape. This was done by cutting of the sample or by adding some material. The determined properties are compared to the properties obtained from the tests on standard specimens. The methods of testing are discussed and evaluated.

鉄筋コンクリート補強された歴史的煉瓦造建造物に生じる白華現象のメカニズム : 煉瓦中の含水量が白華現象に及ぼす影響

It is indicated that the reinforcement with concrete causes efflorescence and decay of brick because of alkali salts in cement. This paper explains the mechanism of efflorescence on historical brick masonry buildings reinforced with concrete. First, accelerated test method was developed so as to reproduce efflorescence on brick masonry wall reinforced with concrete. Second, we investigated relation between water content and rate of evaporation. It is considered that water did not move in a liquid condition in the brick below the water content of 4〜5Vol%. Finally, model wall specimen similar to actual historical brick masonry wall was made and accelerated test was carried out. And water content of each brick was continuously measured by TDR(Time Domain Reflectometry) method during the test. It is concluded that efflorescence did not occur 4〜5Vol% water content below because movable water in liquid phase was not present in the brick.

The Susceptibility of Historic Brick Masonry to Decay

The aim of this paper is to determine why, and in what manner, brick decays. Samples of brick and salt efflorescence were taken from a church in northern Spain and analysed for mineralogical and structural changes, and soluble salts. The effects of decay on brick mineralogy and texture were studied using polarizing microscopy and scanning electron microscopy (SEM) provided with energy dispersive X-ray analysis (EDXA); salts were identified by X-ray diffraction (XRD). Physical tests were used to assess the susceptibility of bricks to decay by moisture, freeze-thaw cycling and salt weathering. Mortars were examined to determine if they contributed to salt decay process in the brick. The paper concludes that, for the samples investigated, salt weathering predominated. Many of these salts, which include halite (NaCl), niter (KNO3) and gypsum (CaSO4), as well as aluminium salts, were transported from the ground into the wall by means of capillary action.

Expert system for evaluation of deterioration of ancient brick masonry structures

The aim of the research on brick masonry degradation supported by the D.G. XII is presented. The project has delivered a damage atlas of ancient brick masonry, a book with a description of the types of damage, and their possible causes, in ancient brick masonry structures and Masonry Damage Diagnostic System (MDDS), an expert computer system allowing the user to define damage types and damage causes in ancient brick masonry structures. The scientific methodology used for the development of both documents is given. Illustration of the MDDS is done through explaining the type, processes and cause of damage that occurs to historic brick masonry structures related to air pollution and traffic.