Sporosarcina pasteurii use in extreme alkaline conditions for recycling solid industrial wastes.

The ureolytic bacteria are one of the most efficient organisms able to produce high amounts of carbonate that easily react with the free calcium ions from the environment. Sporosarcina pasteurii, a robust microbe in alkaline environments, was tested in this work for its potential use in an eco-cementation process that involves the biomediated calcite precipitation (BCP). Bacterial behavior in extreme alkaline environment (pH values of 9-13) was tested in controlled laboratory conditions and in the presence of solid industry wastes, such as Cement Kiln Dust (CKD) and Lime Kiln Dust (LKD), by evaluating the enzymatic activity and the calcite precipitation capacity. Grain consolidation potential of S. pasteurii was tested for one type of CKD mixed with ground granulated blast-furnace slag (GGBS), with possible bioclogging and biocementation applications. The results revealed the formation of stable biocalcite in the presence of CKD, with a performance depending on the pH-value and free calcium ion content. The BCP induced by S. pasteurii and the recycling of solid wastes, such as CKD with high lime content, is a promising way for different bioclogging and biocementation applications, with benefits in construction costs and reduction of environmental pollution.

Standardization of peeling tests for assessing the cohesion and consolidation characteristics of historic stone surfaces.

A peeling test known as the "Scotch Tape test" has been used for more than 40 years in conservation practice for assessing the consolidation efficiency of degraded stone. However, the method has not been supported by any standard or reliably verified recommendations for its application. Its applicability is overestimated, and its unrestricted use without adequate knowledge and sufficient understanding can lead to non-comparable, non-reproducible and, in many cases, incorrect and severely biased results and assessments. This paper presents the results of a recent study focused on establishing limits for application, reliable procedures and a "standard" protocol for testing the cohesion characteristics of brittle and quasi-brittle materials, mainly mortars and stones. The main application strategy exploits repeated peeling in the same place on a surface in order to eliminate the effect of the natural decrease in the detached material from the subsurface layers, which might be incorrectly interpreted as a consolidation effect. There is a discussion of factors influencing the performance of the peeling test method, and examples of peeling measurements on various natural and artificial stones are presented.