The effect of temperature on bacterial self-healing processes in building materials

This paper is focused on the bacterial induced calcitation for the crack healing. The bacteria applied for this purpose are from group which is adapted for growth in the high pH environment as a concrete in hydration phase and their metabolic activity leads to create of calcite. In this study, three different bacteria strains (Sporosarcina pasteurii, Bacillus cohnii, Bacillus pseudofirmus) were applied and the influence of various temperatures on their microbial properties was investigated. Our previous experiment indicated that one of the applied bacterial strain in spores form (Bacillus pseudofirmus) are able to survive the temperatures in the range from −20 °C to 140 °C. The xperiment described in this paper extends the previous study and determines the effect of different temperatures on the change in growth activity. In this experiment, bacterial activity was determined based on the change of absorbance in 640 nm by spectrophotometric measurements. The experiment was performed at optimal temperature (30 °C) and lower temperature (10 °C) and it used suitable broth for calcitation. The results showed that the beginning of metabolic activity was shifted by 40 to 50 hours. Only Bacillus cohnii showed different results because its metabolic activity was nearly zero at 10 °C

Comparison of the Capacitance Method and the Microwave Impulse Method for Determination of Moisture Profiles in Building Materials

A comparison of the capacitance method and the microwave impulse method for the determination of moisture profiles in three typical porous building materials is presented in this paper. The basic principles of the measuring methods are given. The calibration process is described in detail. On the basis of the measured results, it can be concluded that the capacitance method provides better accuracy in the range of lower moisture content than to the microwave impulse method, which is more accurate for the highest values of moisture content.

Mechanical, Hygric and Thermal Properties of Flue Gas Desulfurization Gypsum

The reference measurements of basic mechanical, thermal and hygric parameters of hardened flue gas desulfurization gypsum are carried out. Moisture diffusivity, water vapor diffusion coefficient, thermal conductivity, volumetric heat capacity and linear thermal expansion coefficient are determined with the primary aim of comparison with data obtained for various types of modified gypsum in the future.

Mechanical, Hygric and Thermal Properties of Flue Gas Desulfurization Gypsum

The reference measurements of basic mechanical, thermal and hygric parameters of hardened flue gas desulfurization gypsum are carried out. Moisture diffusivity, water vapor diffusion coefficient, thermal conductivity, volumetric heat capacity and linear thermal expansion coefficient are determined with the primary aim of comparison with data obtained for various types of modified gypsum in the future.

Recycling of fines from waste concrete: development of lightweight masonry blocks and assessment of their environmental benefits

A significant body of research has been carried out to find suitable waste materials or industrial by-products that could replace portland cement and reduce the environmental footprint of the concrete industry. Many studies focus on technical aspects, lacking an assessment of environmental impacts associated with using these alternative materials, and the contribution to the sustainability of the sector remains unclear. In this paper, we present the development of lightweight blocks containing the finest fractions of waste concrete along with a holistic study of the developed product’s structural and environmental performance. The results demonstrate the feasibility of such a recycling strategy and its environmental benefits. However, despite replacing 60 wt.% of portland cement in the developed lightweight blocks, their carbon footprint is not negligible, and to reduce CO2 emissions in the construction sector significantly will require holistic measures that promote the reuse of whole building elements instead of their disintegration and subsequent recycling