The influence of spent catalyst from catalytic cracking in fluidized bed (FCC) on the hydration of two kinds of calcium aluminate cements (of about 40 and 70% content of alumina) was studied. Cement pastes were prepared with constant ratio of water/binder = 0.5 and with content of 0, 5 and 25% mass of addition as replacement of cement. The samples were stored at room temperature. Thermal analysis (TG, DTG), infrared absorption (FTIR) and X-ray diffraction methods were applied to investigate changes in various periods of hydration (up to 150 days). The compressive strength of cement mortars was also examined. On the basis of presented results it was affirmed that in studied conditions spent FCC catalyst is a reactive addition in calcium aluminate cement (CAC) pastes, which probably can create a new phase type C–A–S–H. It may be an interesting alternative for limitation of the negative phenomenon of conversion of aluminate hydrates, although the degree of the influence of the mineral additive depends on the composition of CAC and of the quantity of the used waste.

The article presents measurements of sorptivity. They were performed not only, as usual, after 28 days, but also after longer periods of time (2, 3, 6, 9, 12, 24 months) on samples made of the same concrete. Four different concretes were researched. Differences between the initial value of sorptivity and further measured ones were statistically tested. Results of measurements and tests proved that the initial value of sorptivity can be regarded as quite an exact approximation of further measured values of this parameter

This article deals with an experimental study concerning the development of concrete mixtures with significant ecological benefits. The studied concrete mixtures were based on blast-furnace cement, with an additional application of supplementary cementitious materials—fly ash, metakaolin, and silica fume and fluidized fly ash. Coarse aggregate in the form of crushed concrete was applied for all studied concrete mixtures. The experimental program was primarily focused on the assessment of the durability properties of the studied mixtures in terms of mechanical tests, absorption tests, chloride migration coefficient tests, water penetration tests, and accelerated carbonation depth tests. The results obtained showed good potential for waste materials in durable concrete production. The studied mixtures, with incorporated supplementary cementitious materials, exceeded the level of high performance concrete (HPC) in terms of mechanical properties. Such modification of the binding system also significantly contributed to an increase in durability properties; however, mixtures with the fluidized fly ash application exhibited reduced resistance to carbonation.

Influence of SCM on the Permeability of Concrete with Recycled Aggregate

We can observe the growing tendency of usage of recycled concrete aggregate (RCA). Changes in waste materials management rules will result in necessity of more common reutilization of materials from demolished concrete structures. Thus new fields of RCA application and new ways of its utilization in concrete manufacturing are still being looked for.Research presented in the paper has been conducted to examine two methods of improving poor gradation of natural aggregate (NA) using RCA. The NA that did not fulfill requirements of gradation had been chosen. It consisted of ca. 75% of 2-4mm fraction. In the first method a part of NA was replaced with 2-16 fraction of RCA of low quality. In the second method also a part of NA was replaced this time with 4-8mm and 8-16mm fractions of good quality RCA. The amount of replacing fractions was precisely calculated in order to fit optimal gradation curve. Quality of the gradation was measured with so called gradation index. Mechanical properties of researched concretes was tested as well as some of their properties related to durability. It can be stated, on the basis of the results, that both methods improve most of the vital concrete properties