Architectural conservation and repair are becoming increasingly important issues in many countries due to numerous prior improper interventions, including the use of inappropriate repair materials over time. As a result, the composition of repair masonry mortars is now being more frequently addressed in mortar research. Just recently, for example, it has become apparent that Portland cement mortars, extensively exploited as repair mortars over the past few decades, are not suitable for repair because of their chemical, physical, mechanical, and aesthetic incompatibilities with original materials. This paper focuses on the performance of various lime-based alternative materials intended for application in repairing historic structures when subjected to mechanical loading. Results of basic material tests indicate that the use of metakaolin as a pozzolanic additive produces mortars with superior strength and sufficiently low shrinkage. Moreover, mortar strength can be further enhanced by the addition of crushed brick fragments, which explains the longevity of Roman concretes rich in pozzolans and aggregates from crushed clay products such as tiles, pottery, or bricks. An integrated experimentalnumerical approach was used to identify key mortar parameters influencing the load-bearing capacity of masonry piers subjected to a combination of compression and bending. The simulations indicate increased load-bearing capacities for masonry piers containing metakaolin-rich mortars with crushed brick fragments, as a result of their superior compressive strength.

The paper introduces development of new type of high-performance Portland cement based composite applicable for number of practical utilization. The fundaments of performed research was to design mixture with controlled process of hydration, easy production, suitable time of setting, good workability and rapid evolution of mechanical properties as well as satisfactory long-term stability of hardened composite. Selected mixture were evaluated by means of mechanical properties and volume changes determination.

This paper describes the fundamental principles for the development of high performance composites applicable in severe condition. Studied composite is based on the advanced silicate matrix consisted of cement and suitable addition modifying mineral additives. Experimental work was focused on the study of the evolution of mechanical properties and determination of frost resistance of developed composite at early age, what is crucial parameter for quick reconstruction. Obtained results confirmed that the action of frost did not interrupted the process of hydration of developed binding system, because index of frost resistance determined on the base of studied mechanical properties had increasing trend during the freeze/thaw cycling. Present paper declares high potential of silicate binders for difficult application.

The aim of this study was to quantify the restrained shrinkage of high performance concrete (HPC). Ring test was used for the measurement of restrained shrinkage. Mechanical properties of the HPC as well as free shrinkage were determined for assessment of theoretical stress in shrinkage restrained material. The results from the ring test showed a lot of information about material such as development of actual residual stress, cracking potential, microcracks and relaxation.

Performed research work is focused on the experimental determination of volume changes of high-performance concrete. Studied topic is an essential problem of all cement based composites because of its influence to mechanical and durability properties due to crack formation. Special high-performance cement based mortars are often used for quick rehabilitation and renovation of current concrete structures where minimal level of total volume changes is required. Interpretation of final results is highly dependent on the way of measuring, as it is documented in the present experimental program.