Evaluation of fracture parameters of bond in stone masonry units bound with fibre reinforced mortar

This paper describes the dynamic response of sandstone masonry units bound with fibre-reinforced mortars comparing a Portland cement-lime system with hydraulic lime. A drop-weight impact machine was used to generate stress rates up to 107 kPa/s. The dynamic impact factor and stress rate sensitivity were evaluated for the flexural strength of the sandstone and mortar, and for the bond strength of the unit, and further, the pattern of failure was noted in the units for each mortar mix and loading rate. Polypropylene microfibres were incorporated at 0%, 0.25% and 0.5% volume fraction into the mortar. Results show that the flexural bond strength was more sensitive to stress rate than the flexural strength of the mortar, at similar rates of loading. Further, the stress rate sensitivity of the bond strength decreased with an increase in the fibre content. Also, whereas the flexural toughness factors for the stone-mortar bond fell with fibre reinforcement in the stronger Portland cement-lime system, the bond improved with fibre addition when employing hydraulic lime mortar.

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ASSESSMENT OF COMPRESSIVE STRENGTH OF HISTORIC MIXED MASONRY

Journal of Civil Engineering and Management ◽

10.3846/13923730.2014.914088 ◽

2015 ◽

Vol 22 (3) ◽

pp. 391-400 ◽

Cited By ~ 2

Author(s):

Jiří WITZANY ◽

Tomáš ČEJKA ◽

Miroslav SÝKORA ◽

Milan HOLICKÝ

Keyword(s):

Probabilistic Model ◽

Mechanical Characteristics ◽

Probabilistic Approach ◽

Stone Masonry ◽

Masonry Structures ◽

Non Destructive Testing ◽

Destructive Testing ◽

Non Destructive ◽

Masonry Units ◽

Physical And Mechanical Characteristics

The majority of load-bearing masonry structures of historic buildings are built of mixed or stone masonry composed of regular or irregular (so-called quarry) masonry units – bricks, sedimentary and metamorphic rock – possessing often very different physical and mechanical characteristics. The identification of residual mechanical properties of stone or mixed masonry of irregular walling units requires the application of a suitable diagnostic method, the assessment of the phase of degradation processes and the choice of an appropriate probabilistic model for the strength of mixed masonry. The presented experimental research involves the analysis of the heterogeneity (homogeneity) of mixed masonry of a church from the 17th century. The probabilistic model for masonry strength is developed on the basis of destructive and non-destructive testing of masonry units and mortar. It appears that the probabilistic approach leads to a design value by 75% higher than the deterministic approach.

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