The ettringite, which is the main phase that gives strength to the hardened binder, results in limited shrinkage or even expansion of the material. If it is found, such a strong correlation could be an important argument for recognizing the equivalence of both these tests in the assessment of the quality of pavement concrete.Ĭalcium sulfoaluminate cements are characterized by a very fast start of setting, as well as a very fast increase in early strength (several hours). Additionally, the attempt to find a correlation between the results of the concrete permeability test and its resistance to cyclic freeze-thawing in the presence of de-icing salts is worth noting. Although this parameter is known and quite commonly tested, and concretes using CSA cement are also not new, the combination of these two elements, i.e., the permeability testing of hybrid concrete, has a novelty value, especially in connection with the use of aeration admixture. The measurable features of concrete that correlate well with the quality of its structure include air permeability. Due to difficult working conditions, such a concrete should also have a high durability, which is ensured by a properly shaped structure. The proper direction of the research is the simultaneous use of liquefying, air-entraining and retarding admixtures combined with the use of quick-setting cement, e.g., CSA, as a partial substitute for classical cements based on Portland clinker The resulting hybrid concrete, i.e., made with more than one type of binder, should have a short setting time and high resistance to cyclic freezing. It is a challenge to develop an optimal material composition, which will enable the quick repair of the concrete surface, and at the same time will be characterized by high frost resistance. However, they are rarely used with aeration, which increases the frost resistance of concrete. Repair materials using calcium sulfoaluminate cement (CSA) or other types of quick-setting cements are known. They are a source of chloride ions, which penetrate deep into the concrete, reacting with portlandite to form leachable compounds, which weakens the concrete structure. Another important cause of concrete pavement damages, such as surface scaling and cracking, is the widespread use of de-icing salt in winter. It may also be a result of random events during operation (e.g., leakage of chemicals harmful to concrete during transport). This may result from faults at the execution stage. However, with the increasing length of the concrete road network, the probability increases that repair works will be necessary in some of its sections during their expected service life.
The cement concrete pavement, if properly designed, constructed and exploited, shows a significantly higher durability than the bituminous pavement. In Poland, which is located in the temperate climate zone, the total length of roads with concrete pavement has significantly increased in recent years, and there are plans to build further road sections.
#Solar ash torrent series
On the basis of a multi-criteria evaluation of the tested concrete and performed Performance Index calculations, the best parameters were achieved by concrete series C30-4.5. A clear correlation between sorptivity, air permeability and surface scaling was not found. The series with 30% calcium sulfoaluminate cement in the binder, regardless of aeration, showed significantly lower resistance to cyclic freezing in the presence of salt. It was found that the addition of 15% and 30% calcium sulfoaluminate cement results in a significant reduction in the relative humidity of the concrete, after storage under air-dry conditions and an increase in air permeability. Freeze-thaw scaling resistance was also investigated.
#Solar ash torrent torrent
After 56 and 90 days, the moisture content of the specimens was determined, and Torrent air permeability was tested. Compressive strength tests after 2, 7, 28, 56 and 90 days, tensile splitting strength test and sorptivity test after 28 days were performed. It was assumed that the mixture must remain workable for at least 45 min and to ensure that citric acid as the setting retarder was used. In part of the series, an air-entraining admixture was used. This paper presents the results of research on series of concrete prepared with Portland cement CEM I 42.5R, with partial replacement of this cement with calcium sulfoaluminate cement.
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