Łukasz Kotwica

Bio: Łukasz Kotwica is an academic researcher from AGH University of Science and Technology. The author has contributed to research in topics: Cement & Pozzolan. The author has an hindex of 8, co-authored 26 publications receiving 241 citations.

Incorporation of Al in C-A-S-H gels with various Ca/Si and Al/Si ratio: Microstructural and structural characteristics with DTA/TG, XRD, FTIR and TEM analysis

Abstract: Systems of different Ca/Si and Al/Si molar ratios were investigated. Incorporation of Al increases main basal spacing, amount of bounded water and decreases crystallinity of C-(A)-S-H (calcium (aluminium) silicate hydrate). Transmission electron microscope observations showed that aluminium results in formation of more compacted, foil-like microstructure. FTIR revealed the presence of rings within the structure of C-(A)-S-H. Low Ca/Si ratio promotes Al incorporation into C-(A)-S-H, while in case of high Ca/Si ratio aluminium is also incorporated into AFm. The results show, that Ca/Si ratio is of key significance deciding on Al incorporation into C-(A)-S-H in hydrating SCMs bearing blended systems.

Utilization of waste expanded perlite as new effective supplementary cementitious material

Abstract: Expanded perlite is a valuable lightweight material for building materials industry as well as for agriculture, horticulture etc. Unfortunately during both production as well as processing of expanded perlite, some fine grained waste perlite is being formed. Due to its extremely low bulk density waste expanded perlite is difficult to handle, utilize and causes dust formation. Paper presents method of utilization of waste expanded perlite as a valuable, high performance pozzolanic supplementary cementitious material. Waste expanded perlite was ground in ball mill in order to destroy cellular microstructure of waste expanded perlite. It resulted in significant increase in specific surface area of material. Results of strength tests showed, that addition of ground waste expanded perlite may result in strength gain up to 50% (for 35% addition in respect to cement mass). Due to its high activity ground waste expanded perlite can be used as both cement substitute as well as cement additive depending on desired properties of final material. Investigations showed, that ground waste expanded perlite is material of pozzolanic activity. Except strength test, pozzolanic activity was investigated by solubility test according to ASTM C379-65T. Direct measurements of calcium hydroxide content in hydrating alite pastes confirmed that ground expanded perlite reacts with calcium hydroxide what results in reduction of calcium hydroxide content in alite paste. Pozzolanic activity of ground waste expanded perlite was compared with commonly used commercial pozzolanas. Obtained results allow to classify ground waste expanded perlite as material of pozzolanic properties. It can be valuable supplementary cementitous material mainly for special applications due to its high pozzolanic activity and very bright, almost white colour. In addition to that, ground waste expanded perlite used as cement replacement allows to decrease carbon dioxide emission, since Portland cement manufacturing is connected with emission of considerable amount of carbon dioxide.

Study of pozzolanic action of ground waste expanded perlite by means of thermal methods

Abstract: The DTA/TG and calorimetric measurements were applied in testing the effect of fine-grained waste expanded perlite as an active component of cement mixtures The studies were performed with aim to evaluate the kinetics of cement hydration and the modification of phase composition in the presence of additive The series of mixtures were produced with perlite 2–35 % added to cement The acceleration of cement hydration was proved due to the pozzolanic reaction between the active amorphous fine-grained perlite An attempt to elucidate the mechanism of cement–perlite interaction was presented, based on the results of bound water content by TG measurements

Cement-based composites with waste expanded perlite - Structure, mechanical properties and durability in chloride and sulphate environments

Abstract: Implementation of fine, dusty materials generated during the production of expanded perlite is a challenge from the waste disposal point of view. However, after proper treatment, it is possible to use them in the composite building materials manufacturing where they can play a role of so-called pozzolanic additive, strengthening setting and hardening process when mixed with cement. In this study waste expanded perlite – Portland cement composites were exposed to the action of sodium chloride, sodium sulphate and magnesium sulphate solution. The results show that the durability of cement composites with waste expanded perlite is significantly improved; the lifecycle of these materials would be markedly enhanced. Due to the pozzolanic reaction between the vitreous aluminosilicate component of perlite and calcium hydroxide released from cement clinker, the phase assemblage of hardened cement matrix is changed towards the partial replacement of calcium hydroxide by the C-S-H phase. The amount of calcium hydroxide is therefore markedly reduced, as well as the pore refinement and compact microstructure of products is observed. As a consequence, the compressive strength increases, the permeability of final material decreases. Therefore the durability of Portland cement - perlite mortars is significantly improved. The reference mortars with cement subjected to the sodium and magnesium sulphate started to expand after 200 and 100 days of curing respectively. They were destroyed after about a year, while the samples containing 20% of WEP exhibited no expansion after 5 years of storage in corrosive solutions.

The effect of highly reactive pozzolanic material on the early hydration of alite – C3A – gypsum synthetic cement systems

Abstract: Paper focuses on the mechanism of hydration of synthetic cements consist of alite, tricalcium aluminate and gypsum with variable amounts of highly reactive pozzolanic material – ground waste expanded perlite (WEP). Hydration was traced using conductometric studies of slurries together with calorimetric, XRD, SEM and thermal analysis of pastes. The presence of ground WEP causes faster renewal dissolution of the C3A phase due to faster consumption of sulphate ions. The results suggest an accelerated transformation of ettringite to monosulphate in the presence of WEP. The formation of a larger amount of C-S-H phase which has immobilisation properties to SO42− ions was found.

Recent progress in low-carbon binders

Abstract: The development of low-carbon binders has been recognized as a means of reducing the carbon footprint of the Portland cement industry, in response to growing global concerns over CO2 emissions from the construction sector. This paper reviews recent progress in the three most attractive low-carbon binders: alkali-activated, carbonate, and belite-ye'elimite-based binders. Alkali-activated binders/materials were reviewed at the past two ICCC congresses, so this paper focuses on some key developments of alkali-activated binders/materials since the last keynote paper was published in 2015. Recent progress on carbonate and belite-ye'elimite-based binders are also reviewed and discussed, as they are attracting more and more attention as essential alternative low-carbon cementitious materials. These classes of binders have a clear role to play in providing a sustainable future for global construction, as part of the available toolkit of cements.

A comprehensive overview about the influence of different additives on the properties of alkali-activated slag – A guide for Civil Engineer

Abstract: The development of new binders, as an alternative to Portland cement (PC), by alkaline activation, is a current researchers interest. Alkali-activated slag (AAS) binder is obtained by a manufacturing process less energy-intensive than PC and involves lower greenhouse gasses emission. AAS belongs to prospective materials in the field of Civil Engineering. Researchers have employed fibres, chemical admixtures, mineral admixtures and other materials as additives in AAS system aiming to modify some properties of this system. This paper presents a comprehensive overview of the previous works carried out on using different additives in AAS system.

Effects of expanded polystyrene (EPS) particles on fire resistance, thermal conductivity and compressive strength of foamed concrete

Abstract: This paper deals with the contribution of expanded polystyrene (EPS) particles on fire resistance, thermal conductivity and compressive strength of foamed concrete. The foamed (FC) and polystyrene foamed (PFC) concrete were designed for densities ranging from 1200 kg/m3 to 150 kg/m3 with an EPS volume range of 0–82.22% and water-cement ratio of 0.33. The foamed concrete (FC) with a density of 800 kg/m3 and an EPS volume of 0% was designed as reference for polystyrene foamed concrete. The results indicated that increasing the volume of EPS causes a significant reduction of thermal conductivity, fire endurance and compressive strength of concrete.

Green concrete composite incorporating fly ash with high strength and fracture toughness

Abstract: Nowadays green buildings are a necessary component of securing sustainability, whereas concrete composites with the addition of siliceous fly ash (FA) can certainly be included in the sustainable and green concrete. Effective promotion of green concrete incorporating FA is required in order to minimize the environment threat due to FA waste disposal and reduce cement consumption. In this paper, effects of FA addition on the compressive strength f cm and fracture toughness of plain concrete are presented. Fracture toughness tests were carried out according to Mode I (tension at bending) following the RILEM Draft Recommendations. The critical values of stress intensity factors, K Ic S have been determined. To assess mechanics parameters compressive strength tests and fracture toughness tests were conducted and the results were evaluated comparing with reference concrete. In modified concretes, cement was replaced by FA by its weight. Three test groups were constituted with the replacement percentages as: 0% (FA-00), 20% (FA-20) and 30% (FA-30). During the tests, the effect of age of concretes modified with the additive of FA on analysed parameters was determined. The experiments were carried out after: 3, 7, 28, 90, 180 and 365 days of curing. Based on the obtained results it can be concluded that, it is possible to make green concrete containing FA with high compressive strength and fracture toughness. The properties of composites with the additive of FA depend on the age of the concrete during tests. 20% additive of FA guarantees high f cm and K Ic S in mature concretes. Moreover results of the K Ic S and the f cm are convergent qualitatively.

A synopsis about perlite as building material – A best practice guide for Civil Engineer

Abstract: Perlite is a common name for amorphous volcanic silicate/alumina rock which can be expanded when rapidly heated at 900–1200 °C. Utilization occasions of perlite have made the product adjustable to abundant applications in construction, petrochemical industries, industrial, chemical and horticultural. In construction, expanded perlite (EP) can be used as a part of cement or aggregate in traditional cementitious materials or as a source material for geopolymers. EP in construction deals good thermal and sound insulation, good fire resistance and low density. Subsequently perlite seems to be a very important material. In this paper, the author reviews the effect of EP which used as a part of building material on fresh properties and hardened properties of traditional cementitious materials, geopolymers as well as other binders. Furthermore, different additives which used to improve some properties of EP matrices have been reviewed.