Widespread opinion holds that calcareous rocks have limited suitability for use in the production
of aggregates and stone products having adequate frost resistance. However, some of the rocks, in
particular those from earlier geological periods, provide a promising alternative to silicate rocks.
The paper presents results of the analysis of Devonian carbonate rock originating from two selected
mines in the Swietokrzyskie region. The examined mines extract limestone from two different
deposits of the same age. The rock samples are collected from beds lying at different depths, distinct
in texture and color in macroscopic examination. It was found that despite the changes in bulk density,
porosity and absorption, all the examined samples were frost resistant.
Using the Differential Analysis of Volumetric Strain method, the content of ice formed in the pore
spaces was determined. In addition, the ratio of the content of water capable of freezing to the total
pore volume, and the total amount of water absorbed due to capillary action in rock samples soaked
in water, were analyzed. In all cases, it was revealed that the destructive action of freezing water was
weakened due to a relatively low content of water capable of freezing and a substantial volume of
pores that are not filled with water in capillary absorption.
It is extremely important to be able to classify the available rock material. The generally adopted
methods, including absorptivity tests, do not allow for precise categorization. In the investigations,
the authors focused on the analysis of the basic factors that are decisive for rock durability, including bulk density, pore filling level and volume absorption. The authors do not correspond compressive
strength and resistance to abrasion as this will be the subject of further research.
The technology of recycling with foamed bitumen is a new technology of road rehabilitation. Due to the climatic conditions in the Central European countries, road pavement structure should be moisture and frost resistant. Because of its specific production conditions, this is especially important for pavements rehabilitation with the cold recycling technology. Determining the physical and mechanical properties, as well as moisture and frost resistance, depends on binder and filler contents. They are the key elements before its use for road building. The tests presented here have been performed on mineral recycled base mixes with foamed bitumen. The material from the existing layers was used. The content of bitumen binder amounted to 2.0%, 2.5%, 3.0% and 3.5%, while that of cement to 1.0%, 1.5%, 2.0%, 2.5%. The results were subject to the optimization process. This allowed to state that with the use of 2.5% foamed bitumen and 2.0% of cement, the base had the required properties, as well as the moisture and frost resistance.
In the latest period hundreds of concrete viaducts were built in Poland within a short time range. The cases of destruction of concrete road viaducts described by the author in the article concern in the construction of such structures in various parts of our country, such as central regions of Poland, Warmia-Masuria, south – east - a total of about 30 objects. The occurring phenomenon is related to the micro cracks of the cement matrix which are not visible on the surface of the elements and become visible only after the cyclic freezing process as a result of the standard F150 frost resistance test, the so-called the standard method according to Annex N to the PN-B-06265: 2018 standard. The destruction took an unprecedented course and aroused much discussion in the scientific community. This article summarizes this discussion and indicates the root cause of the destruction.
For the decreasing of too high air volume in SCC, application of anti-foaming admixture (AFA) is proposed. In effect, AFA is increasing mix flow diameter and decreasing the flow time. Moreover, the workability loss is lower. In case of mix incorporating AFA, their high fluidity do not generate segregation of the mix, which is possible in case of SCC incorporating only SP. The effect of AFA application on the compressive strength depends on the proportions between SP and AFA. AFA has not a negative influence on the freeze-proof properties of the tested concrete. The advisable influence of AFA on porosity characteristic of SCC is proved by research results according to EN 480-11 code.