The paper presents an assessment of the impact of using additives on the strength of a binding material, i.e., building gypsum, and also the phase transformation that takes place in it. Microspheres, aerogel and polymer (HEMC) additives were added to a building gypsum slurry with a water to gypsum ratio of 0.75. In order to investigate their influence on bending strength, compressive strength, and the effect of high temperatures, differential scanning calorimetry (DSC), as well as tests of the multicomponent binder, were carried out in accordance with the applicable PN-EN 13279-2:2005 standard. The obtained test results allowed to determine that the used additives influenced the strength parameters of the obtained composites. It was shown that the applied additives decreased the compressive and bending strength of the modified gypsum. Despite these properties, the obtained gypsum materials are environmentally friendly because they reuse wastes, such as microspheres. Out of all the applied additives, the use of microspheres in an amount of 10% caused a decrease in the bending strength by only 10%, and an increase in the compressive strength by 4%.
The article presents the results of testing the effect of partial replacement of sand with fine copper slag waste on the thermal properties of hardened concrete. The impact of the replacement on mechanical properties (ie. compressive and tensile strength of concrete) was also investigated. The thermal properties of the concrete were determined using the non-stationary method with the ISOMET 2114 device. Tests were performed on concrete containing three different types of cement (CEM I, CEM II and CEM III). A total cement content of 360 kg/m 3 was assumed in the compositions of all concrete mixes with a water-cement ratio of 0.45. Replacing 66% of the sand volume with copper slag waste caused a decrease in thermal conductivity by about 4-8% in relation to the reference concrete. In addition, the compressive strength of concrete containing copper slag increased by about from 4-21% in relation to the reference concrete.
The presented work includes experimental data on the infl uence of lightweight filler on the thermal conductivity of λ gypsum. In this research, cenospheres were used. Cenospheres were added in the amount of 10% in respect to the mass of gypsum. To measure thermal conductivity, a non-stationary method was used based on the “hot wire method”. A decrease of thermal conductivity and density with added lightweight filler was observed because of microstructure modifications of the gypsum product. Additional microscopic images of the fractures of the modifi ed gypsum were made.
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