"RIV/68407700:21110/12:00198816!RIV13-MSM-21110___" . "978-80-260-2357-9" . . . . "Effect of Gamma Irradiation on Pore -Space of Hardened Cement Paste"@en . "Effect of Gamma Irradiation on Pore -Space of Hardened Cement Paste" . . "Prague" . "S" . . "Kapi\u010Dkov\u00E1, Olga" . . "133058" . "3"^^ . "Vod\u00E1k, Franti\u0161ek" . "RIV/68407700:21110/12:00198816" . "Czechoslovak Association for Crystal Growth" . . "21110" . "concrete; cement paste; gamma radiation"@en . "Vydra, V\u00EDt\u011Bzslav" . "DEVELOPMENT OF MATERIALS SCIENCE IN RESEARCH AND EDUCATION" . "3"^^ . "Hardened cement paste (HCP) has been exposed to \u03B3-irradiation up to a dose of 1 MGy and then the changes of properties of the porous space were studied by mercury porosimetry and adsorption of nitrogen. It was found that the concentration of nanopores in the hardened cement paste increases and the concentration of pores with a diameter in the range of 10 - 50 nm decreases due to \u03B3-irradiation. The most significant change induced by irradiation is the specific pore area A and AM. It can be interpreted as coarsening of an originally smooth surface of the pores. It corresponds to our hypothesis of so-called %22radiation carbonation%22 of the HCP: the crystals of calcite growing during the carbonation decrease diameter of the pores and increase their surface. There is, however, another hypothesis about the effect of \u03B3-irradiation on HCP: the \u03B3-irradiation causes the radiolysis of water and this leads to drying of samples and can there- fore result in the shrinkage of HCP. Our experiments really show that the relative change of mass of the control samples was only 1 %, but the relative change of mass of the irradiated samples was up to 6 %. Therefore, the shrinkage due to drying may also explain an observed decrease of the mean (average) pore diameter, the specific volume of pores and porosity. It can also explain (contrary to the %22radiation carbonation%22 hypothesis) that the bulk density and the skeleton density did not change their values due to irradiation. Nevertheless, it cannot explain a marked increase in the pore surface. Besides this shrinkage is usually accompa- nied by creation of microcracks that should be expressed as an increase of volume of pores. Our experimental results can be most likely interpreted by two independent phenomena: the shrinkage due to radiation drying and radiation carbonation."@en . . . . "[1E0BFBBACAF8]" . "1"^^ . . . . "Hardened cement paste (HCP) has been exposed to \u03B3-irradiation up to a dose of 1 MGy and then the changes of properties of the porous space were studied by mercury porosimetry and adsorption of nitrogen. It was found that the concentration of nanopores in the hardened cement paste increases and the concentration of pores with a diameter in the range of 10 - 50 nm decreases due to \u03B3-irradiation. The most significant change induced by irradiation is the specific pore area A and AM. It can be interpreted as coarsening of an originally smooth surface of the pores. It corresponds to our hypothesis of so-called %22radiation carbonation%22 of the HCP: the crystals of calcite growing during the carbonation decrease diameter of the pores and increase their surface. There is, however, another hypothesis about the effect of \u03B3-irradiation on HCP: the \u03B3-irradiation causes the radiolysis of water and this leads to drying of samples and can there- fore result in the shrinkage of HCP. Our experiments really show that the relative change of mass of the control samples was only 1 %, but the relative change of mass of the irradiated samples was up to 6 %. Therefore, the shrinkage due to drying may also explain an observed decrease of the mean (average) pore diameter, the specific volume of pores and porosity. It can also explain (contrary to the %22radiation carbonation%22 hypothesis) that the bulk density and the skeleton density did not change their values due to irradiation. Nevertheless, it cannot explain a marked increase in the pore surface. Besides this shrinkage is usually accompa- nied by creation of microcracks that should be expressed as an increase of volume of pores. Our experimental results can be most likely interpreted by two independent phenomena: the shrinkage due to radiation drying and radiation carbonation." . "Lednice" . . . "Effect of Gamma Irradiation on Pore -Space of Hardened Cement Paste" . . "2012-09-03+02:00"^^ . . "Effect of Gamma Irradiation on Pore -Space of Hardened Cement Paste"@en . .