Michał A. Glinicki

Influence of Blended Cements with Calcareous Fly Ash on Chloride Ion Migration and Carbonation Resistance of Concrete for Durable Structures

The objective of this paper is to examine the possible use of new blended cements containing calcareous fly ash in structural concrete, potentially adequate for structural elements of nuclear power plants. The investigation included five new cements made with different contents of non-clinker constituents: calcareous fly ash, siliceous fly ash, ground granulated blastfurnace slag, and a reference cement—ordinary Portland cement. The influence of innovative cements on the resistance of concrete to chloride and carbonation exposure was studied. Additionally, an evaluation of the microstructure was performed using optical microscopy on concrete thin sections. Test results revealed a substantial improvement of the resistance to chloride ion penetration into concrete containing blended cements. The resistance was higher for increased clinker replacement levels and increased with curing time. However, concrete made with blended cements exhibited higher depth of carbonation than the Portland cement concrete, except the Portland-fly ash cement with 14.3% of calcareous fly ash. The thin sections analysis confirmed the values of the carbonation depth obtained from the phenolphthalein test. Test results indicate the possible range of application for new cements containing calcareous fly ash.

Assessment of Scaling Durability of Concrete with CFBC Ash by Automatic Classification Rules

AbstractThe objective of this investigation was to develop rules for automatic assessment of concrete quality by using selected artificial intelligence methods based on machine learning. The range of tested materials included concrete containing nonstandard waste material—the solid residue from coal combustion in circulating fluidized bed combustion boilers (CFBC ash) used as an additive. Performed experimental tests on the surface scaling resistance provided data for learning and verification of rules discovered by machine learning techniques. It has been found that machine learning is a tool that can be applied to classify concrete durability. The rules generated by computer programs AQ21 and WEKA by using the J48 algorithm provided a means for adequate categorization of plain concrete and concrete modified with CFBC fly ash as materials resistant or not resistant to the surface scaling.

Plate impact testing method for GRC materials

Abstract The paper reports on the impact performance evaluation of glass fibre reinforced cement (GRC) materials. The paper includes a review of the principles of impact testing methodology and a proposal for a new test method consisting of a drop weight instrumented impact on plate specimens. The significance of impact test data is discussed with regard to the parasitic effects on impact load versus time records. An application of digital filtering treatment provided the load-displacement characteristics reflecting the specimen response alone. The following impact features of the GRC elements were determined: the maximum impact load, the energy absorbed up to the maximum load and the energy absorbed up to total failure. The energy absorption capability of GRC plates was studied as a function of plate thickness and impact velocity. A comparison of the impact data and the reference quasi-static tests yielded a ratio of impact-to-static energy absorption of 1·7–1·8 for the GRC elements considered.

Prediction of the Chloride Resistance of Concrete Modified with High Calcium Fly Ash Using Machine Learning

The aim of the study was to generate rules for the prediction of the chloride resistance of concrete modified with high calcium fly ash using machine learning methods. The rapid chloride permeability test, according to the Nordtest Method Build 492, was used for determining the chloride ions’ penetration in concrete containing high calcium fly ash (HCFA) for partial replacement of Portland cement. The results of the performed tests were used as the training set to generate rules describing the relation between material composition and the chloride resistance. Multiple methods for rule generation were applied and compared. The rules generated by algorithm J48 from the Weka workbench provided the means for adequate classification of plain concretes and concretes modified with high calcium fly ash as materials of good, acceptable or unacceptable resistance to chloride penetration.

APPLICATION OF MACHINE LEARNING FOR PREDICTION OF CONCRETE RESISTANCE TO MIGRATION OF CHLORIDES

The objective of this research was to develop rules for automatic categorization of concrete quality using selected artificial intelligence methods based on machine learning. The range of tested materials included concrete containing non-conventional additive of solid residue from coal combustion in fluidized bed boilers (CFBC fly ash). Performed experimental tests on chloride migration provided data for learning and testing of rules discovered by machine learning techniques. The rules generated by computer programs AQ21 and WEKA using J48 algorithm provided means for adequate categorization of plain concrete and concrete modified with CFBC fly ash as materials of good and acceptable resistance to chloride penetration.

Influence of calcerous fly ash on concrete resistance to migration of chlorides

The use of caleerous fly ash from brown coal combustion in Belchatow Power Plant in Poland as additive to concrete mix was studied. The strength and the resistance to chloride penetration into concrete was investigated at water to binder ratio from 0.45 to 0.60. Caleerous fly ash both in unprocessed form and grinded to specified specific surface was used for partial replacement of cement up to 30% of mass. To evaluate the concrete resistance to chloride ion penetration the standard method of determination of chloride migration coefficient from non-steady-state migration test according to NT Build 492 was used. Test results revealed a substantial improvement of the resistance to chloride penetration into concrete containing calcerous fly ash. The resistance was higher for increased replacement level and decreased water-to-cement ratio.

Effect of the Loading rate on the Tensile strength of Concrete

The knowledge of the loading rate influence on the tensile strength of concrete is of considerable importance in engineering practice. The safety of several concrete structures subjected to impact and impulsive loads is often controlled by the tensile strength and stress-strain behaviour because these properties greatly influence the cracking of concrete, bond properties of reinforcing steel and behaviour under shear forces.

Application of Image Analysis to Identify Quartz Grains in Heavy Aggregates Susceptible to ASR in Radiation Shielding Concrete

Alkali-silica reaction (ASR) is considered as a potential aging-related degradation phenomenon that might impair the durability of concrete in nuclear containments. The objective of this paper is the application of digital analysis of microscopic images to identify the content and size of quartz grains in heavy mineral aggregates. The range of investigation covered magnetite and hematite aggregates, known as good absorbers of gamma radiation. Image acquisition was performed using thin sections observed in transmitted cross-polarized light with λ plate. Image processing, consisting of identification of ferrum oxide and epoxy resin, and the subsequent application of a set of filtering operations resulted in an adequate image reduction allowing the grain size analysis. Quartz grains were classified according to their mean diameter so as to identify the reactive range. Accelerated mortar bar tests were performed to evaluate the ASR potential of the aggregates. The SiO2 content in the heavyweight aggregates determined using the image analysis of thin sections was similar to XRF test result. The content of reactive quartz hematite was 2.7%, suggesting that it would be prone to ASR. The expansion test, according to ASTM C1260, confirmed the prediction obtained using the digital image analysis.

Microhardness testing procedure applied to blended cement based matrix

In the paper a new method of determination of cement paste microhardeness is presented. It includes the procedure of systematic indentation with a Vickers tip and a statistical processing of population of obtained results. The tested specimens were cast with different kinds of blended cements, containing high calcium fly ash (HCFA) as one of major components. Differences in values of microhardeness obtained for six series of tested specimens mixes are discussed and compared with compressive strength of investigated materials.

Tensile stress-strain behaviour of cementitious composites at high loading rates

The influence of loading rate on the tensile stress-strain behaviour of cementitious composites was studied experimentally. The project was undertaken to obtain an insight into the possible relation between internal structure parameters of composites and their loading-rate sensitivity. Five different types of cementitious composites were applied. Composite structure data were obtained by testing porosity and by quantitative observation of fracture surfaces. Direct tensile tests were performed at four different loading rates within the range 0.001–1000 MPa s−1. The tensile stress-strain behaviour was significantly influenced by the loading rate and structure parameters of composites. The relative tensile strength increase due to an increase of loading rate was found to be higher for composites with higher total porosity. Recorded stress-strain diagrams obtained at various loading rates are presented and discussed with the aid of continuous damage mechanics.