A study of immobilization of hexavalent chromium in the form of Na2CrO4 salt by self-compacting soils (SCS) is presented. Carbofill E additive was used as SCS binder. The efficiency of immobilization of Cr (VI) was evaluated by washing out chromium compounds from SCS samples. The influence of the nature of the soil and the content of Carbofill E and Na2CrO4 in the SCS samples on the efficiency of Cr (VI) immobilization was studied. It was found that the nature of the soil and the content of Carbofill E in the SCS samples affect the immobilization of Cr (VI). Moreover, increasing the Carbofill E content in SCS samples further increases Cr (VI) immobilization. X-ray diffraction studies of the samples with immobilized hexavalent chromium showed that part of the sample transforms from a readily soluble form of salt into oxide forms of chromium and calcium-chromium, which are practically insoluble in water.
By classifying BIM data, the intention is to enable different construction actors to find the data they need using software and machines. The importance of classification is growing as building projects become more international, generating more data that rely on automated processes, which help in making better decisions and operating devices. Different classification systems have been developed around the world. Each national construction information classification system (NCICS) aims to classify information on the built environment and thus meet national needs and ensure compliance with the principles of regional and international building information systems. The research purpose of this paper is to present a comparative assessment of two construction information classification systems, CCI and Uniclass 2015. The following methods were used: the expert assessment of NCICS alternatives; the assessment of NCICS alternatives; and a strengths, weaknesses, opportunities, and threats (SWOT) analysis of NCICS alternatives. We concluded that in the initial phase of NCICS development, CCI ontologies should be adopted as a base consisting of construction entities, spaces, and elements, with the gradual addition of complexes of buildings and infrastructure, along with roles and phases of the building life cycle (BLC). An explanatory NCICS development note should be drawn outlining the principles of classification and identification; the ontological structure; development and updating possibilities; methods of integrating existing national and international classification systems; and methods of integrating data of construction products, time, cost, or other individual characteristics.
In this paper the properties and the hydration of Portland cement pastes containing zeolitized silica fume were studied. Hydrosodalite was obtained by zeolitization of silica fume. XRD, DSC, SEM and energy-dispersive X-ray spectroscopy were used as investigation methods. The compressive strength of hardened cement paste was measured after 28 days. The levels of cement replacement by additives were 5 %, 10 % and 15 % by weight in the specimens. Changes in the strength of hardened cement paste were observed. The influence of additives on hydration rate and hydration temperature was also observed. Both 1Hs (hydrosodalite) and 2Hs (modified hydrosodalite) additives accelerate the hydration of the cement paste. The highest hydration temperature was achieved in a mixture with 5 wt. % 1Hs additive and with 10 wt. % 2Hs additive. The microstructure of hardened cement paste specimens with 1Hs and 2Hs additive is denser compared with reference specimens without the additives. The maximum compressive strength of the specimens with 10 wt. % of 2Hs reached up to 101 MPa under laboratory conditions.
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