[en] In the cement industry, grinding aids can be used to improve the efficiency, promote the realization of the concept of energy saving and emission reduction, and reduce the production cost to a great extent. Cement grinding aid is a kind of material which can promote cement grinding, and it is an important part of energy-saving development of industry at present. It can not be ignored in improving cement technology. Based on this, this paper analyzes the influencing factors of grinding aid effect in cement grinding process. (paper)

[en] Cement samples commonly used in building constructions in Egypt and Yemen were analyzed for natural radioactivity using a Hyper-pure Germanium detector (HPGe). The radioactivity content of ²³⁸U, ²³²Th and ⁴⁰K isotopes in the cement samples was studied. In the Egyptian cement samples, the specific activities for mentioned isotopes were found as follows: for ²³⁸U, ranged 18 - 35 Bq/kg, with an average value of 27.9±6.9 Bq/kg; for ²³²Th, ranged 7.2 - 16.1 Bq/kg, with an average value of 13.1±4.1 Bq/kg; for ⁴⁰K, ranged 24.8 -107.1 Bq/kg, with an average value of 73.3 ± 35.2 Bq/kg. In the Yemenian cement samples, specific activities for mentioned isotopes were found as follows: for ²³⁸U, in the range 19.6 – 193 Bq/kg, with an average of 68.8± 71.9; for ²³²Th, in the range 17.3 – 256 Bq/kg, with an average of 79.1±102.2 Bq/kg; for ⁴⁰K, in the range 272.7-858.6 Bq/kg, with an average of 421.6±252.3 Bq/kg. In both country cases, the specific activities were compared with the reported data in other countries and world average limits (global values reported in UNSCEAR publications). The determined specific activity of ²³⁸U, ²³²Th and ⁴⁰K was found to be less than the world average values (50 Bq/kg, 50 Bq/kg and 500 Bq/kg, respectively, for the considered nuclides) except for Block waver cement samples. It was shown that the averages of radiation hazard parameters and the annual effective dose for cement samples are lower than the accepted level of 370 Bq/kg for Radium equivalent (Ra_eq) and lower than unit for internal hazard index, the external hazard index and the annual effective dose, except for Block waver cement samples. Excluding the Block waver cement samples, the rest of cement samples do not pose radiological hazards when are used as materials for buildings construction. (author).

[en] Cement is the basic material for constructions which is made from a mixture of elements that are found in natural materials such as limestone, marl and/or clay. Cement manufacturing is an energy and resource intensive process with both local and global environmental, health and safety impacts. Because of these impacts, ensuring healthy and safe working conditions for employees is one of the most significant issues for the cement industry. In this review, cement manufacturing process was clarified briefly and potential hazards and their risks in cement industry were investigated.

[en] Demolition ceramic wastes (DCWs) were investigated in order to determine their potential use as supplementary cementitious materials in Portland Blended Cements (PBCs). For this purpose, three ceramic wastes were investigated. After characterization of the materials used, the effect of ceramic waste replacement (8, 24 and 40% by mass) was analyzed. Pozzolanic activity, hydration progress, workability and compressive strength were determined at 2, 7 and 28 days. The results showed that the ground wastes behave as filler at an early age, but as hydration progresses, the pozzolanic activity of ceramic waste contributes to the strength requirement.

[en] The influence of secondary fuels components used for Portland clinker production on emission value of heavy metals is presented in this paper. Analyses and studies of hazardous substances emission (heavy metals) from cements and concretes were conducted according to standards developed by Technical Committee CEN TC 351. The contents of following heavy metals were analyzed: Cr, Zn, Cd, Pb, Co, Ni, Mn, Cu, Sr, Ba and P in secondary fuels used by cement industry in Poland for Portland clinker production. Total heavy metal contents in cements and their leaching from cements CEM I were studied. Leaching of heavy metals from CEM I-based concretes to environment was also determined. Obtained tests results allow to conclude that changes in technology of cement clinker production leading to the usage of waste materials and secondary fuels does not cause an increase in heavy metals emission in level, which requires qualifying cement as material, which has to be regularly controlled for harmfulness on man and natural environment. (paper)

[en] Besides bricks, granites and sands cement is one of the main components of building materials Cement is made from a combination of rocks and soils which is known to contain natural radioactivity. The objectives of this study were to determine the level of natural radioactivity and associated radiological hazard caused by natural radioactivity in Malaysia's Portland cements. Portland cements samples were obtained from the manufacturers or bought directly from local hardware stores. Natural radionuclide concentrations of ²²⁶Ra (²³⁸U series), ²³²Th and ⁴⁰K were determined using gamma-ray spectrometry. Activity concentrations of ²²⁶Ra (²³⁸U series), ²³²Th and ⁴⁰K were found in the range of 7.76 - 82.91 Bq kg^-1, 9.79 - 49.37 Bq kg^-1 dan 81.89 - 377.10 Bq kg^-1 respectively. Radium equivalent were found in the range of 35.36 ± 0.60 to 135.94 ± 15.27 Bq kg^-1 while the average annual equivalent dose and internal hazard index were found in the range of 80 ± 2 to 300 ± 30 μSv year^-1 and 0.12 ± 0.00 to 0.56 ± 0.07 respectively. (author)

[en] The main purpose of the research is to study the lightweight cement slurry based on vermiculite and its parameters in accordance with GOST 1581-96 requirements as well as improvement of its formulation by polymer additives. Analysis of vermiculite-containing mixture providing the lowest density while maintaining other required parameters was conducted. As a cement base, cement PTscT-I-G-CC-1, cement PTscT – 100 and vermiculite M200 and M150 were used. Vermiculite content varied from 10 to 15 %; and water-to-cement-ratio ranged from 0.65 to 0.8. To sum up, despite the fact that lightweight cement slurry based on vermiculite satisfies GOST 1581-96 requirements under laboratory conditions, field studies are necessary in order to make a conclusion about applicability of this slurry for well cementing

[en] In many radioactive waste repository designs, cement-based materials are expected to dominate the repository and models of cement evolution predict that leaching of the cementitious material in the repository by groundwater will produce an initial stage of hyperalkaline (pH - 13.3) leachates, dominated by alkali hydroxides, followed by a longer period of portlandite and C-S-H (CaO-SiO₂-H₂) buffered (PH - 12.5) leachates. It has also been predicted that, as the hyperalkaline porewater leaches out of the near-field, significant interaction with the repository host rock and bentonite buffer and backfill may occur. This could possibly leak to deterioration of those features for which the host rock formation and bentonite were originally chosen (e.g. low groundwater flux, high radionuclide retardation capacity etc). The precise implication of cement leachate/repository host rock interaction has been studied in the laboratory and in underground research laboratories (URLs) and this work has been supported by study of natural cements in Jordan. These natural cements have been produced by the combustion of organic-rich clay biomicrites and are very close analogues of industrial cement. Following interaction with groundwaters, natural hyperalkaline leachates are produced and these move out of the cement into the surrounding host rock, subsequently interacting with and altering it. (author)

[en] The factors that define the efficiency of earthed coating shields made of the Portland cement-based electroconductive cementing composition were experimentally studied to provide the electrocorrosion protection. It was established that the current intensity is increased by the three orders of magnitude as the current flows through the water-saturated earthed coating shield made of the Portland cement-based electroconductive composition. This fact confirms the feasibility of the use of such shields to drain the leakage currents that are considerably increased achieving unsafe values especially in wet weather. It was also established that protective shield properties depend on the ratio of the contact area of the coating-shielded steel earth electrode to the area of entire coating shield. As this ratio is increased the intensity of the current flowing through the structure reinforcement and concrete is decreased and the intensity of current flowing through the earthed coating shield is increased. It confirms the efficiency of the use of earthed coating shields made of the Portland cement-based electroconductive compositions to provide the electrocorrosion protection caused by leakage currents, for example for such structures as railway d. c. current-electrified passenger platforms. (paper)

[en] The authors deal with the problem of electron paramagnetic resonance application for the examination of cement minerals. The theoretical foundations of the method and experimental technique are presented and the advantages of this new method are emphasized. Also the possibility for application of this method, in future, in rapid examination of cement raw materials reactivity for the sake of new cement plant design as well as for industrial practice, is mentioned. (author)