Gintautas Skripkiunas - Academia.edu (original) (raw)
Papers by Gintautas Skripkiunas
Lecture notes in civil engineering, Oct 24, 2023
Solid State Phenomena, Jun 1, 2018
There are many research devoted to the influence of carbon nanotubes (CNT) on the structure and p... more There are many research devoted to the influence of carbon nanotubes (CNT) on the structure and properties of cement systems. In the course of this research, the combined influence of of multi-walled carbon nanotubes (MWCNT) and polycarboxylate (PCE) plasticizer on the products of hydration and the properties of hardened cement paste was investigated. The strength characteristics of nanomodified hardened cement paste and the hydration products were determined by the usage of modern methods of physico-mechanical and physico-chemical analyses. Based on the physico-chemical investigations, it was concluded the necessity of additional experiments, associated primary with questions of uniform distribution of the nanostructures and their chemical interactions with another components of admixture and cement system.
Reziumė Disertacijoje aprašytuose tyrimuose buvo pasirinkti du aktyvūs mineraliniai priedai: nema... more Reziumė Disertacijoje aprašytuose tyrimuose buvo pasirinkti du aktyvūs mineraliniai priedai: nemaltas katalizatorius iš katalitinio naftos krekingo reaktoriaus (KAT) ir nedegta mulitinė vata (MV). Galimybės šias atliekas naudoti keramzitbetonio gamyboje iki šiol netirtos. Pagrindinė tyrimo tematika-aktyviųjų mineralinių priedų (KAT ir MV) įtaka pagrindinėms keramzitbetonio charakteristikoms. Disertacijoje sprendžiami keli pagrindiniai uždaviniai: ištirti aktyviųjų mineralinių priedų poveikį cemento hidratacijos mechanizmui, apskaičiuoti prognozuojamą eksploatacinį atsparumą šalčiui bei, remiantis tyrimų rezultatais, parinkti geriausius KAT ir MV atliekos kiekius keramzitbetonio mišiniuose. Disertaciją sudaro įvadas, keturi skyriai, bendrosios išvados, naudotos literatūros ir disertacijos autorės publikacijų sąrašai. Įvadiniame skyriuje aptariama tiriamoji problema, darbo aktualumas, aprašomas tyrimų objektas, formuluojamas darbo tikslas ir uždaviniai, aprašoma tyrimų metodika, darbo mokslinis naujumas, darbo rezultatų praktinė reikšmė, ginamieji teiginiai. Pirmasis skyrius skirtas literatūros analizei. Skyriaus pabaigoje pateikiamos išvados ir formuluojami disertacijos uždaviniai. Antrajame skyriuje aprašyti tyrimų metodai ir įranga, bandinių paruošimo technologijos, keramzitbetonio mišinių sudėtys, naudotų žaliavų charakteristikos. Trečiajame ir ketvirtajame skyriuose pateikti rezultatai apie aktyviųjų mineralinių priedų poveikį pagrindinėms keramzitbetonio savybėms, mikrostruktūrai, mišinių cemento hidratacijai ir apskaičiuotas keramzitbetonio prognozuojamas eksploatacinis atsparumas šalčiui. Darbo pabaigoje suformuluotos bendrosios išvados. Disertacijos tema paskelbti du straipsniai, kurie įtraukti į Thomson ISI sąrašą, du-Inspec duomenų bazėje cituojamame žurnale, vienas-recenzuojamame tarptautinės konferencijos straipsnių rinkinyje, vienas-kitame leidinyje. Disertacijos tema perskaityti šeši pranešimai Lietuvos ir užsienio konferencijose. Remiantis tyrimų rezultatais pateikta paraiška sukurtam keramzitbetoniui patentuoti.
Cement & Concrete Composites, 2018
The aim of this study was to investigate the properties of concrete containing various quantities... more The aim of this study was to investigate the properties of concrete containing various quantities of copper indium selenide (CIS) solar module waste by replacing a certain part (up to 40%) of sand. The obtained results have shown that an increase in the content of solar module waste resulted in an increase of the density of fresh and hardened concrete. The compressive strength of the specimens compared to the control specimens has been higher, when sand aggregate was replaced by CIS solar module waste particles from 5 to 20%. Also, in all cases a decrease in the water absorption and porosity of concrete specimens containing immobilized waste compared to those with no waste has been observed. The leaching behaviour of the concrete containing immobilized waste was also studied. The results showed that the concrete with sand aggregate replacement by waste particles between 5 to 10% has the best leaching properties. That replacement can be used for CIS solar module waste recycling in concrete production.
Construction and Building Materials, Mar 1, 2017
h i g h l i g h t s Mineral additives are among the most promising of concrete components in the ... more h i g h l i g h t s Mineral additives are among the most promising of concrete components in the development of new building materials. Replacement of cement with mineral additives can be increased concrete density, compressive strength, freeze-thaw resistance. Mineral additives can be used for modification of cementations systems.
Journal of physics, May 1, 2021
Architectural concrete has wide opportunities to be used both for exteriors and interiors in diff... more Architectural concrete has wide opportunities to be used both for exteriors and interiors in different buildings. Architectural concrete is the type of concrete which is usually not subjected to finishing, therefore higher standards are declared for its surface quality. According to normative documents, architectural concrete needs to have a uniform colour tone, texture, minimal defects and porosity of the surface. The present research demonstrates the concrete surface quality obtained in the course of varying different factors such as the presence of stabilizing admixture, granulometry of aggregates, usage of fly ash and workability of the concrete mixture. In the course of the research, the testing of raw materials and concrete in the fresh and hardened state were performed according to standard methodologies. The assessment of concrete surface quality was provided through the analysis of concrete surface photo 50x50 cm size. Based on the experimental results, it can be stated that better quality of the concrete surface was obtained in case of usage of gravel with two fractions of 4/16 and 2/8 and fly ash in the dosage of 25 % cement weight in the presence of plasticizing and stabilizing admixtures. The concrete mixture with high workability showed better filling of formwork and mixture particles packing on the formwork surface which led to a better quality of the concrete surface.
Engineering Structures and Technologies, Dec 31, 2019
It is well known that organic waste materials deteriorate the performance of concrete. The impreg... more It is well known that organic waste materials deteriorate the performance of concrete. The impregnation of organic aggregates and their application in combination with other chemical admixtures and mineral additives are used in order to improve the concrete properties in case of their modification by organic components. The current research is focused on the evaluation of impact of multi-walled carbon nanotubes (MWCNT) on the properties of cement systems prepared based on wood sawdust extract (WSE). The setting time, density, consistency, flexural and compressive strength, water absorption tests were undertaken. The retardation effect of (WSE) on the initial and final setting time of cement paste was observed. The additional modification of cement paste with WSE by MWCNT in the dosage of 0.005% by weight of cement (bwoc) did not show the significant changes in initial and final setting time. The application of MWCNT in the dosage of 0.005% bwoc contributed to the increase of early strength of cement mortar prepared with WSE.
Construction Science, 2017
The article analyses the reactivity level of aggregates from Lithuanian quarries and their effect... more The article analyses the reactivity level of aggregates from Lithuanian quarries and their effect on the alkali corrosion in mortars. The reactivity of aggregates was assessed according to Rilem Recommended Test Method: AAR-2. The hardened cement paste and cracked aggregate contact zones were tested by means of optical microscopy. Two gravel aggregates and one sand aggregate from Lithuanian quarries were selected for testing. The tests revealed that according to AAR 2 methodology fine and coarse aggregates from Lithuanian quarries shall be allocated to Group II, i.e. reactive aggregates. The expansion after 14 days exceeds 0.1 % in the case of fine aggregate, the average expansion after 14 days is 0.13 %, and in the case of coarse aggregates the average expansion ranges from 0.11 % to 0.12 %.
IOP conference series, Oct 1, 2017
The influences of aggregate combination and inhibitor additives on the Alkali-silica Reaction (AS... more The influences of aggregate combination and inhibitor additives on the Alkali-silica Reaction (ASR) were studied in this research. A long-term alkali activity simulation of fully-graded concrete also was carried out. The results showed that replacement of artificial sandstone sand with artificial marble sand reduced the alkali activity expansion rate of the sandstone aggregate and effectively improved the inhibition effect of the aggregate when mixed with 35 % fly ash. Activated silica in the fly ash was crushed into particles and was mixed into each part of the concrete system. It transformed the limited parts into unlimited active centers. As a result, each center participated in the reaction and consumed the alkali. Inhibition of the ASR was effective when the fly-ash content of the ASR-1 was 15 %, while in the ASR-2, the fly-ash did not have a significant inhibition effect. During a long-term simulation, the expansion rate of theconcrete specimens after standard curing at 20 °C was higher than was the expansion rate after outdoor natural curing. The expansion rate of full sandstone concrete specimens was higher than was that of sandstone specimens that contained marble stone.
Journal of Materials in Civil Engineering, Jul 1, 2018
AbstractThe rheological properties of concrete mixtures are presently important when new technolo... more AbstractThe rheological properties of concrete mixtures are presently important when new technologies for transporting, handling, placing, and compacting concrete are used in new concrete construct...
Baltic Journal of Road and Bridge Engineering, Sep 30, 2016
Concrete paving blocks that were started to be used in the last century have become very popular.... more Concrete paving blocks that were started to be used in the last century have become very popular. They became an alternative to the natural stone. Concrete paving blocks are used for the paving of pedestrian and vehicle zones. Durability is one of the main characteristics in the production of high-quality concrete paving blocks in the Baltic region climate zone. The article describes tests with concrete paving blocks, the top layer of which contains 5% of synthetic zeolite admixture obtained by means of low temperature synthesis in laboratory conditions. This zeolite admixture is obtained from aluminium fluoride production waste. The durability of concrete paving blocks was tested according to abrasion resistance, tensile splitting strength, absorption and frost resistance. The test results revealed that 5% of zeolite admixture added to the top layer of concrete paving blocks reduce the absorption, increase the tensile splitting strength by more than 10%, and decrease abrasion by 6.5%. The zeolite admixture used in concrete paving blocks reduces the scaling about 4 times after 28 freeze-thaw cycles when 3% NaCl is used as the freezing solution. The tests revealed that synthetic zeolite admixture can be used in concrete elements production by means of vibropressing (pavement elements) to increase their durability.
Engineering Structures and Technologies, Nov 13, 2018
This article presents a research into the impact of plasticising admixtures on drying shrinkage o... more This article presents a research into the impact of plasticising admixtures on drying shrinkage of cementitious composites by evaluating the effectiveness of plasticising. Materials used in the study: Portland cement CEM I 42.5 R, plasticiser LS (modified lignosulphonates based), superplasticiser PCE (synthetic polycarboxylate esters based), superplasticiser MAP (modified acrylic polymers based), sand and water. The percentage change of plastic viscosity of cement paste indicates the effectiveness of plasticising of cementitious composites. The change of plastic viscosity has been tested by adding a specific amount of plasticising admixtures. The effectiveness of plasticising of pastes were tested using rotational viscometer. Chemical admixtures content in pastes varied from 0 to 1.2%. Drying shrinkage was tested based on length change of the specimens with fine aggregates. The method to minimise drying shrinkage of composites was established through use of plasticising admixtures. It has been found that by increasing plasticising admixture dosage from 0 to 1.2% the following changes occur: LS plasticising effectiveness increases by 35% while drying shrinkage decreases by 8%; MAP plasticising effectiveness increases by 70% while drying shrinkage decreases by 16%; PCE plasticising effectiveness increases by 80% while drying shrinkage decreases by 20%.
Materials Science Forum, Aug 1, 2017
The article aims to present a research into the impact of the dosage and effectiveness of superpl... more The article aims to present a research into the impact of the dosage and effectiveness of superplasticizers based on modified acrylic polymer and polycarboxylate ester (from 0 to 1.2 %) on rheological properties of the cement pastes (yield stresses and plastic viscosities), of different testing times after mixing (from 0 to 90 min). Materials used in the study: Portland cement CEM I 42.5 R, superplasticizers SP1 (modified acrylic polymer based), SP2 (polycarboxylate ester based), and water. Investigation was carried out using rotational rheometer Rheotest RN4.1 with coaxial cylinders. The tests revealed that superplasticizer SP2 is more effective than SP1 – cement paste (W/C = 0.30) exhibits better flowability and improved rheological qualities. Superplasticizers SP1 and SP2 exhibit different levels of plasticizing effectiveness and ability to retain the effect’s duration. Due to the increase in the dosage of superplasticizers SP1 and SP2 from 0 to 1.2 %, plasticizing effect increases. It is also observed that larger dosage of SP1 (0.6-1.2 %) results in slower increase in plasticizing effects until the 90 min margin. In conclusion, from the start of mixing until the 90 min margin, the best plasticizing effect and its retention achieved by superplasticizer SP2. Recommended SP2 dosage – from 0.6 to 0.8 %.
Solid State Phenomena, Jun 1, 2018
The influence of concentration of cement particles φc on rheological behavior (flow behavior, dyn... more The influence of concentration of cement particles φc on rheological behavior (flow behavior, dynamic yield stress, plastic viscosity) and thixotropy of the Portland cement CEM I 42.5 R paste was investigated in this research. Also, thixotropy was evaluated by index of reversible structure of Portland cement paste. Concentration of cement particles φc ranged from 0.434 to 0.518. Investigation was carried out using rotational rheometer Rheotest RN4.1 with coaxial cylinders. The tests revealed that as φc decreases from 0.518 to 0.434, rheological behavior of Portland cement paste is improved: yield stress decreases from 12.7 Pa to 7.1 Pa as well as plastic viscosity – from 4.3 Pa·s to 0.88 Pa·s. The exponential correlation between φc and index of reversible structure of Portland cement paste was found. As φc decreases from 0.518 to 0.434, index of reversible structure of Portland cement paste, which describes a thixotropy, decreases from 5291 Pa·min to 977 Pa·min.
Construction and Building Materials, Apr 1, 2017
h i g h l i g h t s Freeze-thaw resistance is the one of the main characteristics evaluating dura... more h i g h l i g h t s Freeze-thaw resistance is the one of the main characteristics evaluating durability. Top paving layer affects the splitting tensile strength results.
Construction Science, 2017
Granite rubble is one of the most frequently used aggregates in concrete manufacturing. Granite r... more Granite rubble is one of the most frequently used aggregates in concrete manufacturing. Granite rubble is considered to be a non-reactive aggregate, however, depending on the quarry, granite may have various impurities including harmful minerals containing active SiO2. The alkalisilica reaction is among the chemical reactions that have a significant effect on the durability of concrete. During the alkalisilica reaction certain forms of silica present in concrete aggregates react with high alkali content leading to formation of hygroscopic gel that expands in humid environment and slowly, although strongly enough degrades concrete structures. Concrete rubble of 3 different fractions was used for the test: 2/8 (Mix D); 11/16 (Mix E); 5/11 (Mix G). The tests revealed that granite rubble used for the tests contained few reactive rocks containing amorphous silica because after 14 days the expansion did not exceed 0.1 % ((D Mix expanded by 0.059 %, E Mix expanded by 0.066 %, G Mix expanded by 0.079 %) according to RILEM AAR-2 test method. After 56 days of testing none of the test specimens demonstrated significant micro-cracking and scaling specific to alkali corrosion; only gel deposits on the surface were observed.
Journal of Civil Engineering and Management, Mar 24, 2016
The rheological properties of the cement pastes have been determined using a rotational viscomete... more The rheological properties of the cement pastes have been determined using a rotational viscometer under a special testing routine by increasing and retaining a steady rotation speed of the viscometer cylinder up to certain values and for a certain time. These tests, using rotational viscometer, have been conducted by making the assessment of cement paste flow curves, using Bingham rheological model. Rheological properties of cement pastes were tested at different times after pastes mixing: 0 min, 30 min, 60 min, 90 min, 120 min and 180 min. Cement pastes with same W/C ratio equal to 0.35 were tested. The content of admixture was used 0%, 0.5%, 1%, 2%, 3% and 5%. The admixture of Ca(NO 3) 2 can be used in cement pastes and concretes without a reduction in consistency during 120 min in the dosage of up to 2%. Dosages of Ca(NO 3) 2 from 3% are not recommended for cement pastes and concrete, they significantly increase the viscosity of mixtures immediately after mixing The admixture of calcium nitrate changes thixotropy of cement pastes. In this case, a bigger dosage of calcium nitrate increases the thixotropy of pastes.
Procedia Engineering, 2017
The aim of this work is to determine the impact of biomass fly ash (BM-FA) on the plasticizing ef... more The aim of this work is to determine the impact of biomass fly ash (BM-FA) on the plasticizing effects in cement pastes. The rheological properties of the cement pastes have been determined using rotational viscometer with coaxial cylinders Rheotest RN4.1. These tests, using rotational viscometer, have been conducted by making the assessment of cement paste flow curves, using Bingham rheological model. The rheological properties (yield stress, viscosity and thixotropy) of cement paste were determined at different times after paste mixing: 0 min, 30 min, 60 min, 90 min and 120 min. The cement pastes with same W/C ratio equal 0.35 were tested. 0 %, 5 %, 10 %, 20 % and 30 % of cement were replaced by BM-FA. The rheological behavior of the cement pastes was also studied and compared to that of a reference BM-FA free production in order to evaluate the effect of BM-FA addition on rheological properties. Results showed that having replaced 10 % of cement with BM-FA the paste exhibits better rheological properties: not only lower yield stress but also lower viscosity from mixing until 120 min after. Adequate amount of BM-FA (10 %, in this case) not only improves rheological properties but also helps retaining plasticizing effect for the period of 120 min, which is important in long distance concrete mixtures transportation. It was observed that having replaced up to 10 % of cement with BM-FA thixotropy was also improved and the fresh concrete mixtures produced can be transported, molded, consolidated, and finished within 90 minutes from mixing without losing good workability and rigidity.
Construction and Building Materials, Aug 1, 2016
Abstract The article analysis the effect of synthetic zeolite on properties of concrete mix and h... more Abstract The article analysis the effect of synthetic zeolite on properties of concrete mix and hardened concrete. Zeolite was obtained from waste of aluminum fluoride production by low-temperature synthesis and added in concrete mix up to 10% as Portland cement replacing admixture. Test results revealed that, replacing cement by synthetic zeolite considerably decreases concrete scaling during freezing and thawing cycles. Compressive strength, density of concrete and water absorption were measured. The test results proved that synthetic zeolite obtained from aluminum fluoride by means of low temperature synthesis can be used as a supplementary cementitious material to increase the durability of concrete.
The compositions and technological parameters of obtaining filtering corundum and quartz ceramic ... more The compositions and technological parameters of obtaining filtering corundum and quartz ceramic materials with functional membrane coatings obtained in the Al2O3–ZnO, Al2O3–Fe2O3, Al2O3–CuO and Al2O3–MnO2 systems were developed; the regularities of the process of formation of a layered porous permeable structure have been established in conjunction with the physicochemical properties, phase composition and performance characteristics of filter materials. Scientifically substantiated and experimentally confirmed the desirability of the use of polyphenylsiloxanes as a binder to obtain porous permeable corundum and quartz ceramics
Lecture notes in civil engineering, Oct 24, 2023
Solid State Phenomena, Jun 1, 2018
There are many research devoted to the influence of carbon nanotubes (CNT) on the structure and p... more There are many research devoted to the influence of carbon nanotubes (CNT) on the structure and properties of cement systems. In the course of this research, the combined influence of of multi-walled carbon nanotubes (MWCNT) and polycarboxylate (PCE) plasticizer on the products of hydration and the properties of hardened cement paste was investigated. The strength characteristics of nanomodified hardened cement paste and the hydration products were determined by the usage of modern methods of physico-mechanical and physico-chemical analyses. Based on the physico-chemical investigations, it was concluded the necessity of additional experiments, associated primary with questions of uniform distribution of the nanostructures and their chemical interactions with another components of admixture and cement system.
Reziumė Disertacijoje aprašytuose tyrimuose buvo pasirinkti du aktyvūs mineraliniai priedai: nema... more Reziumė Disertacijoje aprašytuose tyrimuose buvo pasirinkti du aktyvūs mineraliniai priedai: nemaltas katalizatorius iš katalitinio naftos krekingo reaktoriaus (KAT) ir nedegta mulitinė vata (MV). Galimybės šias atliekas naudoti keramzitbetonio gamyboje iki šiol netirtos. Pagrindinė tyrimo tematika-aktyviųjų mineralinių priedų (KAT ir MV) įtaka pagrindinėms keramzitbetonio charakteristikoms. Disertacijoje sprendžiami keli pagrindiniai uždaviniai: ištirti aktyviųjų mineralinių priedų poveikį cemento hidratacijos mechanizmui, apskaičiuoti prognozuojamą eksploatacinį atsparumą šalčiui bei, remiantis tyrimų rezultatais, parinkti geriausius KAT ir MV atliekos kiekius keramzitbetonio mišiniuose. Disertaciją sudaro įvadas, keturi skyriai, bendrosios išvados, naudotos literatūros ir disertacijos autorės publikacijų sąrašai. Įvadiniame skyriuje aptariama tiriamoji problema, darbo aktualumas, aprašomas tyrimų objektas, formuluojamas darbo tikslas ir uždaviniai, aprašoma tyrimų metodika, darbo mokslinis naujumas, darbo rezultatų praktinė reikšmė, ginamieji teiginiai. Pirmasis skyrius skirtas literatūros analizei. Skyriaus pabaigoje pateikiamos išvados ir formuluojami disertacijos uždaviniai. Antrajame skyriuje aprašyti tyrimų metodai ir įranga, bandinių paruošimo technologijos, keramzitbetonio mišinių sudėtys, naudotų žaliavų charakteristikos. Trečiajame ir ketvirtajame skyriuose pateikti rezultatai apie aktyviųjų mineralinių priedų poveikį pagrindinėms keramzitbetonio savybėms, mikrostruktūrai, mišinių cemento hidratacijai ir apskaičiuotas keramzitbetonio prognozuojamas eksploatacinis atsparumas šalčiui. Darbo pabaigoje suformuluotos bendrosios išvados. Disertacijos tema paskelbti du straipsniai, kurie įtraukti į Thomson ISI sąrašą, du-Inspec duomenų bazėje cituojamame žurnale, vienas-recenzuojamame tarptautinės konferencijos straipsnių rinkinyje, vienas-kitame leidinyje. Disertacijos tema perskaityti šeši pranešimai Lietuvos ir užsienio konferencijose. Remiantis tyrimų rezultatais pateikta paraiška sukurtam keramzitbetoniui patentuoti.
Cement & Concrete Composites, 2018
The aim of this study was to investigate the properties of concrete containing various quantities... more The aim of this study was to investigate the properties of concrete containing various quantities of copper indium selenide (CIS) solar module waste by replacing a certain part (up to 40%) of sand. The obtained results have shown that an increase in the content of solar module waste resulted in an increase of the density of fresh and hardened concrete. The compressive strength of the specimens compared to the control specimens has been higher, when sand aggregate was replaced by CIS solar module waste particles from 5 to 20%. Also, in all cases a decrease in the water absorption and porosity of concrete specimens containing immobilized waste compared to those with no waste has been observed. The leaching behaviour of the concrete containing immobilized waste was also studied. The results showed that the concrete with sand aggregate replacement by waste particles between 5 to 10% has the best leaching properties. That replacement can be used for CIS solar module waste recycling in concrete production.
Construction and Building Materials, Mar 1, 2017
h i g h l i g h t s Mineral additives are among the most promising of concrete components in the ... more h i g h l i g h t s Mineral additives are among the most promising of concrete components in the development of new building materials. Replacement of cement with mineral additives can be increased concrete density, compressive strength, freeze-thaw resistance. Mineral additives can be used for modification of cementations systems.
Journal of physics, May 1, 2021
Architectural concrete has wide opportunities to be used both for exteriors and interiors in diff... more Architectural concrete has wide opportunities to be used both for exteriors and interiors in different buildings. Architectural concrete is the type of concrete which is usually not subjected to finishing, therefore higher standards are declared for its surface quality. According to normative documents, architectural concrete needs to have a uniform colour tone, texture, minimal defects and porosity of the surface. The present research demonstrates the concrete surface quality obtained in the course of varying different factors such as the presence of stabilizing admixture, granulometry of aggregates, usage of fly ash and workability of the concrete mixture. In the course of the research, the testing of raw materials and concrete in the fresh and hardened state were performed according to standard methodologies. The assessment of concrete surface quality was provided through the analysis of concrete surface photo 50x50 cm size. Based on the experimental results, it can be stated that better quality of the concrete surface was obtained in case of usage of gravel with two fractions of 4/16 and 2/8 and fly ash in the dosage of 25 % cement weight in the presence of plasticizing and stabilizing admixtures. The concrete mixture with high workability showed better filling of formwork and mixture particles packing on the formwork surface which led to a better quality of the concrete surface.
Engineering Structures and Technologies, Dec 31, 2019
It is well known that organic waste materials deteriorate the performance of concrete. The impreg... more It is well known that organic waste materials deteriorate the performance of concrete. The impregnation of organic aggregates and their application in combination with other chemical admixtures and mineral additives are used in order to improve the concrete properties in case of their modification by organic components. The current research is focused on the evaluation of impact of multi-walled carbon nanotubes (MWCNT) on the properties of cement systems prepared based on wood sawdust extract (WSE). The setting time, density, consistency, flexural and compressive strength, water absorption tests were undertaken. The retardation effect of (WSE) on the initial and final setting time of cement paste was observed. The additional modification of cement paste with WSE by MWCNT in the dosage of 0.005% by weight of cement (bwoc) did not show the significant changes in initial and final setting time. The application of MWCNT in the dosage of 0.005% bwoc contributed to the increase of early strength of cement mortar prepared with WSE.
Construction Science, 2017
The article analyses the reactivity level of aggregates from Lithuanian quarries and their effect... more The article analyses the reactivity level of aggregates from Lithuanian quarries and their effect on the alkali corrosion in mortars. The reactivity of aggregates was assessed according to Rilem Recommended Test Method: AAR-2. The hardened cement paste and cracked aggregate contact zones were tested by means of optical microscopy. Two gravel aggregates and one sand aggregate from Lithuanian quarries were selected for testing. The tests revealed that according to AAR 2 methodology fine and coarse aggregates from Lithuanian quarries shall be allocated to Group II, i.e. reactive aggregates. The expansion after 14 days exceeds 0.1 % in the case of fine aggregate, the average expansion after 14 days is 0.13 %, and in the case of coarse aggregates the average expansion ranges from 0.11 % to 0.12 %.
IOP conference series, Oct 1, 2017
The influences of aggregate combination and inhibitor additives on the Alkali-silica Reaction (AS... more The influences of aggregate combination and inhibitor additives on the Alkali-silica Reaction (ASR) were studied in this research. A long-term alkali activity simulation of fully-graded concrete also was carried out. The results showed that replacement of artificial sandstone sand with artificial marble sand reduced the alkali activity expansion rate of the sandstone aggregate and effectively improved the inhibition effect of the aggregate when mixed with 35 % fly ash. Activated silica in the fly ash was crushed into particles and was mixed into each part of the concrete system. It transformed the limited parts into unlimited active centers. As a result, each center participated in the reaction and consumed the alkali. Inhibition of the ASR was effective when the fly-ash content of the ASR-1 was 15 %, while in the ASR-2, the fly-ash did not have a significant inhibition effect. During a long-term simulation, the expansion rate of theconcrete specimens after standard curing at 20 °C was higher than was the expansion rate after outdoor natural curing. The expansion rate of full sandstone concrete specimens was higher than was that of sandstone specimens that contained marble stone.
Journal of Materials in Civil Engineering, Jul 1, 2018
AbstractThe rheological properties of concrete mixtures are presently important when new technolo... more AbstractThe rheological properties of concrete mixtures are presently important when new technologies for transporting, handling, placing, and compacting concrete are used in new concrete construct...
Baltic Journal of Road and Bridge Engineering, Sep 30, 2016
Concrete paving blocks that were started to be used in the last century have become very popular.... more Concrete paving blocks that were started to be used in the last century have become very popular. They became an alternative to the natural stone. Concrete paving blocks are used for the paving of pedestrian and vehicle zones. Durability is one of the main characteristics in the production of high-quality concrete paving blocks in the Baltic region climate zone. The article describes tests with concrete paving blocks, the top layer of which contains 5% of synthetic zeolite admixture obtained by means of low temperature synthesis in laboratory conditions. This zeolite admixture is obtained from aluminium fluoride production waste. The durability of concrete paving blocks was tested according to abrasion resistance, tensile splitting strength, absorption and frost resistance. The test results revealed that 5% of zeolite admixture added to the top layer of concrete paving blocks reduce the absorption, increase the tensile splitting strength by more than 10%, and decrease abrasion by 6.5%. The zeolite admixture used in concrete paving blocks reduces the scaling about 4 times after 28 freeze-thaw cycles when 3% NaCl is used as the freezing solution. The tests revealed that synthetic zeolite admixture can be used in concrete elements production by means of vibropressing (pavement elements) to increase their durability.
Engineering Structures and Technologies, Nov 13, 2018
This article presents a research into the impact of plasticising admixtures on drying shrinkage o... more This article presents a research into the impact of plasticising admixtures on drying shrinkage of cementitious composites by evaluating the effectiveness of plasticising. Materials used in the study: Portland cement CEM I 42.5 R, plasticiser LS (modified lignosulphonates based), superplasticiser PCE (synthetic polycarboxylate esters based), superplasticiser MAP (modified acrylic polymers based), sand and water. The percentage change of plastic viscosity of cement paste indicates the effectiveness of plasticising of cementitious composites. The change of plastic viscosity has been tested by adding a specific amount of plasticising admixtures. The effectiveness of plasticising of pastes were tested using rotational viscometer. Chemical admixtures content in pastes varied from 0 to 1.2%. Drying shrinkage was tested based on length change of the specimens with fine aggregates. The method to minimise drying shrinkage of composites was established through use of plasticising admixtures. It has been found that by increasing plasticising admixture dosage from 0 to 1.2% the following changes occur: LS plasticising effectiveness increases by 35% while drying shrinkage decreases by 8%; MAP plasticising effectiveness increases by 70% while drying shrinkage decreases by 16%; PCE plasticising effectiveness increases by 80% while drying shrinkage decreases by 20%.
Materials Science Forum, Aug 1, 2017
The article aims to present a research into the impact of the dosage and effectiveness of superpl... more The article aims to present a research into the impact of the dosage and effectiveness of superplasticizers based on modified acrylic polymer and polycarboxylate ester (from 0 to 1.2 %) on rheological properties of the cement pastes (yield stresses and plastic viscosities), of different testing times after mixing (from 0 to 90 min). Materials used in the study: Portland cement CEM I 42.5 R, superplasticizers SP1 (modified acrylic polymer based), SP2 (polycarboxylate ester based), and water. Investigation was carried out using rotational rheometer Rheotest RN4.1 with coaxial cylinders. The tests revealed that superplasticizer SP2 is more effective than SP1 – cement paste (W/C = 0.30) exhibits better flowability and improved rheological qualities. Superplasticizers SP1 and SP2 exhibit different levels of plasticizing effectiveness and ability to retain the effect’s duration. Due to the increase in the dosage of superplasticizers SP1 and SP2 from 0 to 1.2 %, plasticizing effect increases. It is also observed that larger dosage of SP1 (0.6-1.2 %) results in slower increase in plasticizing effects until the 90 min margin. In conclusion, from the start of mixing until the 90 min margin, the best plasticizing effect and its retention achieved by superplasticizer SP2. Recommended SP2 dosage – from 0.6 to 0.8 %.
Solid State Phenomena, Jun 1, 2018
The influence of concentration of cement particles φc on rheological behavior (flow behavior, dyn... more The influence of concentration of cement particles φc on rheological behavior (flow behavior, dynamic yield stress, plastic viscosity) and thixotropy of the Portland cement CEM I 42.5 R paste was investigated in this research. Also, thixotropy was evaluated by index of reversible structure of Portland cement paste. Concentration of cement particles φc ranged from 0.434 to 0.518. Investigation was carried out using rotational rheometer Rheotest RN4.1 with coaxial cylinders. The tests revealed that as φc decreases from 0.518 to 0.434, rheological behavior of Portland cement paste is improved: yield stress decreases from 12.7 Pa to 7.1 Pa as well as plastic viscosity – from 4.3 Pa·s to 0.88 Pa·s. The exponential correlation between φc and index of reversible structure of Portland cement paste was found. As φc decreases from 0.518 to 0.434, index of reversible structure of Portland cement paste, which describes a thixotropy, decreases from 5291 Pa·min to 977 Pa·min.
Construction and Building Materials, Apr 1, 2017
h i g h l i g h t s Freeze-thaw resistance is the one of the main characteristics evaluating dura... more h i g h l i g h t s Freeze-thaw resistance is the one of the main characteristics evaluating durability. Top paving layer affects the splitting tensile strength results.
Construction Science, 2017
Granite rubble is one of the most frequently used aggregates in concrete manufacturing. Granite r... more Granite rubble is one of the most frequently used aggregates in concrete manufacturing. Granite rubble is considered to be a non-reactive aggregate, however, depending on the quarry, granite may have various impurities including harmful minerals containing active SiO2. The alkalisilica reaction is among the chemical reactions that have a significant effect on the durability of concrete. During the alkalisilica reaction certain forms of silica present in concrete aggregates react with high alkali content leading to formation of hygroscopic gel that expands in humid environment and slowly, although strongly enough degrades concrete structures. Concrete rubble of 3 different fractions was used for the test: 2/8 (Mix D); 11/16 (Mix E); 5/11 (Mix G). The tests revealed that granite rubble used for the tests contained few reactive rocks containing amorphous silica because after 14 days the expansion did not exceed 0.1 % ((D Mix expanded by 0.059 %, E Mix expanded by 0.066 %, G Mix expanded by 0.079 %) according to RILEM AAR-2 test method. After 56 days of testing none of the test specimens demonstrated significant micro-cracking and scaling specific to alkali corrosion; only gel deposits on the surface were observed.
Journal of Civil Engineering and Management, Mar 24, 2016
The rheological properties of the cement pastes have been determined using a rotational viscomete... more The rheological properties of the cement pastes have been determined using a rotational viscometer under a special testing routine by increasing and retaining a steady rotation speed of the viscometer cylinder up to certain values and for a certain time. These tests, using rotational viscometer, have been conducted by making the assessment of cement paste flow curves, using Bingham rheological model. Rheological properties of cement pastes were tested at different times after pastes mixing: 0 min, 30 min, 60 min, 90 min, 120 min and 180 min. Cement pastes with same W/C ratio equal to 0.35 were tested. The content of admixture was used 0%, 0.5%, 1%, 2%, 3% and 5%. The admixture of Ca(NO 3) 2 can be used in cement pastes and concretes without a reduction in consistency during 120 min in the dosage of up to 2%. Dosages of Ca(NO 3) 2 from 3% are not recommended for cement pastes and concrete, they significantly increase the viscosity of mixtures immediately after mixing The admixture of calcium nitrate changes thixotropy of cement pastes. In this case, a bigger dosage of calcium nitrate increases the thixotropy of pastes.
Procedia Engineering, 2017
The aim of this work is to determine the impact of biomass fly ash (BM-FA) on the plasticizing ef... more The aim of this work is to determine the impact of biomass fly ash (BM-FA) on the plasticizing effects in cement pastes. The rheological properties of the cement pastes have been determined using rotational viscometer with coaxial cylinders Rheotest RN4.1. These tests, using rotational viscometer, have been conducted by making the assessment of cement paste flow curves, using Bingham rheological model. The rheological properties (yield stress, viscosity and thixotropy) of cement paste were determined at different times after paste mixing: 0 min, 30 min, 60 min, 90 min and 120 min. The cement pastes with same W/C ratio equal 0.35 were tested. 0 %, 5 %, 10 %, 20 % and 30 % of cement were replaced by BM-FA. The rheological behavior of the cement pastes was also studied and compared to that of a reference BM-FA free production in order to evaluate the effect of BM-FA addition on rheological properties. Results showed that having replaced 10 % of cement with BM-FA the paste exhibits better rheological properties: not only lower yield stress but also lower viscosity from mixing until 120 min after. Adequate amount of BM-FA (10 %, in this case) not only improves rheological properties but also helps retaining plasticizing effect for the period of 120 min, which is important in long distance concrete mixtures transportation. It was observed that having replaced up to 10 % of cement with BM-FA thixotropy was also improved and the fresh concrete mixtures produced can be transported, molded, consolidated, and finished within 90 minutes from mixing without losing good workability and rigidity.
Construction and Building Materials, Aug 1, 2016
Abstract The article analysis the effect of synthetic zeolite on properties of concrete mix and h... more Abstract The article analysis the effect of synthetic zeolite on properties of concrete mix and hardened concrete. Zeolite was obtained from waste of aluminum fluoride production by low-temperature synthesis and added in concrete mix up to 10% as Portland cement replacing admixture. Test results revealed that, replacing cement by synthetic zeolite considerably decreases concrete scaling during freezing and thawing cycles. Compressive strength, density of concrete and water absorption were measured. The test results proved that synthetic zeolite obtained from aluminum fluoride by means of low temperature synthesis can be used as a supplementary cementitious material to increase the durability of concrete.
The compositions and technological parameters of obtaining filtering corundum and quartz ceramic ... more The compositions and technological parameters of obtaining filtering corundum and quartz ceramic materials with functional membrane coatings obtained in the Al2O3–ZnO, Al2O3–Fe2O3, Al2O3–CuO and Al2O3–MnO2 systems were developed; the regularities of the process of formation of a layered porous permeable structure have been established in conjunction with the physicochemical properties, phase composition and performance characteristics of filter materials. Scientifically substantiated and experimentally confirmed the desirability of the use of polyphenylsiloxanes as a binder to obtain porous permeable corundum and quartz ceramics