This paper presents the results of comprehensive cement paste porosity and gas permeability tests. The tests conducted concerned ordinary Portland cement (OPC) cement pastes with varying water-cement ratios ranging from 0.3 to 0.6. The tests were conducted after the curing of cement paste for 90 days and two years under laboratory conditions. Open porosity was determined using three methods: helium pycnometry, mercury intrusion porosimetry, and water saturation. Permeability was determined using a modified RILEM-Cembureau method. The results obtained demonstrated that permeability does not change significantly over time despite the observed material shifts in open porosity characteristics caused both by further progress in hydration and by the carbonation process that occurs. The results of the tests conducted also permitted the quantitative determination of the impact of the water-cement ratio, age, and the progress of carbonation on open porosity measured using different methods and also on the gas permeability of the pastes.

The paper presents experimental investigations concerning the influence of the cement type (CEMI 42.5 R Portland cement and CEMIII/A 42.5 N slag cement—with 53% granulated blast furnace slag) on the mechanical and transport properties of heated concretes. The evolution of properties due to high temperature exposure occurring during a fire was investigated. High temperature exposure produces changes in the transport and mechanical properties of concrete, but the effect of cement type has not been widely studied in the literature. In this paper, concretes were made with two cement types: CEMI and CEMIII, using basalt (B) and riverbed aggregates (RB). The compressive and tensile strength, as well as the static modulus of elasticity and Cembureau permeability, were tested after high temperature exposure to 200, 400, 600, 800, and 1000 °C. The evaluation of damage to the concrete and crack development due to high temperature effects was performed on the basis of the change in the static modulus of elasticity. The test results clearly demonstrated that permeability increases with damage, and it follows an exponential type formula for both types of cement.

This paper presents the results of extensive research work on the open porosity and gas permeability of cement pastes. Tests were conducted on cement pastes with different water/cement ratios and types of cement. The three most popular cements in Poland from the CEM I, CEM II and CEM III groups were tested after the pastes had been cured for 90 days in laboratory conditions. The scope of experiments included the assessment of open porosity determined using three different methods: comparing the bulk and specific densities, mercury intrusion porosimetry and saturating the material with water. In addition, this article contains an analysis of the porosity characteristics based on the distributions produced by porosimetry examinations. Gas permeability was determined using the modified RILEM-Cembureau laboratory method. The results of the completed test allowed a quantitative determination to be made of the impact of water-cement ratio and type of cement used on open porosity assessed by various methods, and the influence of these parameters on the gas permeability of the paste. The quantitative changes in the content of capillary pores and meso-pores in the cement pastes analysed are also presented.

Cement production has the largest carbon-footprint since it leads to the release of carbon dioxide and enormous energy consumption. Therefore, scientific research is being conducted worldwide on the possibility of using other materials that can be used as a cement substitute. A potential alternative material is glass powder. This paper present research results on the use of glass powder as a partial cement replacement with a substitution level of 0–20%. The pozzolanic activity and the influence of glass powder on cement hydration were analyzed. The porosity, the microstructure of the interfacial transition zone and the compressive strength of mortar were also investigated.

This paper presents the results of research on high performance concretes (HPC) modified by the addition of polypropylene fibres (PP fibres). The scope of the research was the measurement of the residual transport properties of heated and recooled concretes: gas permeability and surface water absorption. Seven types of concrete modified with fibrillated PP fibres were tested. Three lengths: 6, 12 and 19 mm and three amounts of fibres: 0, 0.9 and 1.8 kg/m³ were used. The research programme was designed to determine which length of fibres, used in which minimum amount, will, after the fibres melt, permit the development of a connected network and pathway for gases and liquids.

The paper deals with mechanical properties of soil-cement composites made with non-cohesive soil and reinforced with dispersed fibers. The research was carried out on the basis of three soil-cement matrices whose compositions varied in terms of the volumetric fraction of cement paste and the water-cement ratio. Two types of polypropylene fibers were used as dispersed reinforcement: single fibrillated-tapes polypropylene fibers (SFPF) and bundles of coiled fibrillated-tapes polypropylene fibers (BCFPF). The fibers varied in terms of their length and mass fraction. The objective of the study was to assess the effect of the addition of fibers to soil-cement composites on their flexural tensile strength and on their behavior in the post-critical state. The studies were carried out after 28 days of curing. Bending tests were carried out to determine post-critical stress values σ_CMODi, stress values at which the matrix is destroyed (limit of proportionality) σ_LOP, maximum stress values transferred by the fibers σ_MOR (modulus of rupture), and total fracture energy G_f,tot as well as compressive strength. The test results obtained, and their analysis, indicate the significant impact of the dispersed reinforcement used on the performance of such composites during bending.