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This article reviews the manufacturing nanotechnologies of modern refractory concretes and some other cementitious materials. The main part of the article focuses on the results obtained by the authors who analyzed the application of nanotechnology for manufacturing refractory concretes and examined the influence of nanostructure formation in the binding material on the properties of refractory concretes. In one case, investigations were carried out using two‐component (sodium silicate solution mixed with dicalcium silicate) and three‐component (sodium silicate solution mixed with dicalcium silicate plus calcium aluminate cement) binding materials, whereas in other case, multi‐component material, middle cement refractory concrete with mullite aggregates, microsilica and additives of single and hybrid deflocculant (polycarboxylate ether Castament FS20 and sodium tripolyphosphate) were researched. Preliminary investigations showed that the three‐component binding material under development hardens unlike the two‐component material as one of the binding components (combination of sodium silicate solution and dicalcium silicate) hardens very fast and affects the hydration process of the other component, calcium aluminate cement, which has a powerful impact on the whole structure of the already hardened material. The limited amount of water in the hardening structure provides conditions for the formation of the initial nanoclusters and nanolayers of amorphous hydrates. The application of nanotechnology in manufacturing refractory concretes has enabled to increase compressive strength 3 times – from 55 MPa to 165 MPa. Santrauka Straipsnyje apžvelgiamos per pastaraji dešimtmeti sukurtos ugniai atspariu betonu ir kai kuriu kitu cementiniu medžiagu gamybos nanotechnologijos, kurios padeda nagrineti nanostruktūru, susidariusiu kietejant šiu betonu rišamajai medžiagai, itaka fizikinems betonu charakteristikoms. Detaliau apžvelgiami rezultatai, gauti šio straipsnio autoriu, nagrinejusiu nanotechnologiju taikyma ugniai atspariu betonu gamyboje tiriant nanostruktūru susidarymo, kietejant ugniai atspariu betonu rišamajai medžiagai bei ugniai atspariems betonams su mulito užpildu, itaka šiu medžiagu savybems. Autoriu tyrimai atlikti naudojant dvinkomponente (natrio silikato tirpalo ir dikalcio silikato) bei trikomponente (natrio silikato tirpalo, dikalcio silikato ir aliuminatinio cemento) rišamaja medžiaga bei vidutinio cemento kiekio ugniai atsparu betona su SiO2 mikrodulkiu ir hibridinio deflokulianto (natrio tripolifosfatu ir polikarboksilato eteriu) priedu. Preliminarūs tyrimai parode, kad trikomponentis rišiklis kieteja kitaip nei dvikomponentis, nes viena iš rišamuju daliu (natrio silikato tirpalo ir dikalcio silikato kompozicija) kieteja labai greitai ir veikia kito komponento (aliuminatinio cemento) hidratacijos eiga, o tai turi didele itaka visai kietejančiai struktūrai. Ribotas vandens kiekis kietejančioje struktūroje padeda šalia amorfiniu hidratu formuotis nanoklasteriams ir nanosluoksniams. Pritaikius nanotechnologija ugniai atspariu betonu gamyboje, pavyko gerokai padidinti ju termini atsparuma (beveik tris kartus) ir gniuždomaji stipri (nuo 55 MPa iki 165 MPa).

To decrease the environmental impact of the construction industry, energy-efficient insulation materials with low embodied production energy are needed. Lime-hemp concrete is traditionally recognized as such a material; however, the drawbacks of this type of material are associated with low strength gain, high initial moisture content, and limited application. Therefore, this review article discusses alternatives to lime-hemp concrete that would achieve similar thermal properties with an equivalent or lower environmental impact. Binders such as gypsum, geopolymers, and starch are proposed as alternatives, due to their performance and low environmental impact, and available research is summarized and discussed in this paper. The summarized results show that low-density thermal insulation bio-composites with a density of 200–400 kg/m3 and thermal conductivity (λ) of 0.06–0.09 W/(m × K) can be obtained with gypsum and geopolymer binders. However, by using a starch binder it is possible to produce ecological building materials with a density of approximately 100 kg/m3 and thermal conductivity (λ) as low as 0.04 W/(m × K). In addition, a preliminary life cycle assessment was carried out to evaluate the environmental impact of reviewed bio-composites. The results indicate that such bio-composites have a low environmental impact, similar to lime-hemp concrete.

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