Use of calcareous fly ash in SCC

Abstract The robustness of self-compacting concrete (SCC) mixtures is usually sensitive to alterations in the mixture constituents, which is also the case when using high volumes of calcareous fly ash as binder. In the present report, calcareous fly ash was used as 30% and 50% by mass of the total binder without changing the water to binder ratio. The expected loss of workability due to the increased water demand of calcareous fly ash was compensated by adjusting the dosages of the admixtures (superplasticizer and viscosity modifying agent). Slump flow, L-Box and segregation resistance tests were carried out on the fresh mixtures, showing that robust SCC can be produced with the addition of high volumes of calcareous fly ash. Mechanical characteristics of the test mixtures were also measured, showing adequate strength development, comparable to that of the reference concrete, while shrinkage deformations were reduced when higher volumes of calcareous fly ash were used.

Study of materials and technology of ancient floor mosaics’ substrate

A floor mosaic’s substrate is composed of a variety of preparatory layers of mortar built on natural levelled ground or on top of a previous pavement. Mosaics’ substrates differ one from the other in number, thickness and nature of the mortar layers. In this sense, it has been considered relevant to state how these differences are related with historical period, geographical position, function of the pavements within the building, technology of the substrates. A number of floor mosaics’ substrates of Hellenistic and Roman period from archaeological sites in Greece and Italy are under study. The stratigraphy of substrates is recorded in situ, and samples from each mortar layer are analysed in the laboratory by means of different techniques. Results obtained so far indicate that characteristics of the Roman substrates mortar layers are clearly dependant on their position in the substrate stratigraphy, whereas in the case of the Hellenistic substrates, characteristics of the mortar layers are less varying with the stratigraphic position. Furthermore results show that floor mosaics’ substrates are different according to the function of the pavement in the building

Damage analysis as a step towards compatible repair mortars

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