english DAVID RESANO, JOSE BARRANZUELA, FABIOLA UBILLÚS, OSCAR GUILLEN, ANA GALARZA
Rezumat
High-altitude human settlements, such as those in the Andes and the Himalayas, experience extreme temperature conditions, yet many houses in the Peruvian Andes lack thermal insulation due to the unavailability of affordable materials. As a result, respiratory diseases linked to low temperatures are widespread during the coldest months of the year. This study presents the development of an innovative thermal insulation panel made from locally sourced sugarcane bagasse fibers, bonded with polyvinyl acetate and fabricated using compression molding. The panel achieved a thermal conductivity of 0.043 W/m·K, which allows compliance with Peruvian thermal transmittance standards when applied in layers of approximately 6 cm thickness. The material exhibited a bulk density ranging from 86.7 to 105.3 kg/m³. Mechanical testing showed a low average tensile strength of 0.0144 kg/cm² and a flexural modulus of 0.116 kg/cm², indicating that the panel is not suitable for structural applications. However, it is effective as a non-structural thermal insulation solution. The proposed panel promotes a circular economy by repurposing agricultural by-product and offers a low-cost, biodegradable alternative to synthetic and mineral fiber insulations, contributing to reduce material costs and environmental impact in buildings.
Cuvinte cheie
Composite, organic material, sugarcane bagasse fibers, thermal insulation, circular economy
J.JEGAN, P.ANITHA, SUNANTHA B., J SUDHAKUMAR, R.LOGARAJA, KONA PRAVALLIKA PHANI DURGA
Rezumat
Phase-change materials must now be used during construction to reduce greenhouse gas emissions and boost energy efficiency. Considering concrete makes up the majority of construction materials worldwide, incorporating PCMs into concrete can greatly increase a structures energy efficiency. There has been a growing interest in phase change materials (PCMs) in recent years. By utilizing the appropriate PCM and integration approach, the majority of issues associated with utilizing PCM in concrete may be resolved. In this work, Thermal Storage Light Weight Aggregate (TSLWA) was produced by incorporating pumice stone into Paraffin wax. The concrete cube were cast with different replacement ratios of TSLWA with LWA such as 0%, 25%, 50%, 75%, and 100%. The study revealed that increasing PCM content reduced water absorption, with the control sample absorbing 8.5% water compared to only 1.8% for the 100% PCM sample. Compressive strength decreased with higher PCM percentages, with the 100% PCM sample showing significant reduction, emphasizing the need for a balance between thermal properties and structural integrity. Thermal analysis showed that paraffin wax exhibited thermal transitions around 50°C, demonstrating stable thermal behavior up to 300°C. Microstructural examination revealed altered bonding strength due to paraffin wax-filled aggregates, and leakage tests highlighted the effectiveness of epoxy resin coatings in reducing water seepage. Overall, PCM-impregnated pumice concrete improves moisture resistance and thermal performance, offering a promising solution for sustainable construction, though careful consideration of PCM concentration is needed to maintain mechanical strength.
Cuvinte cheie
thermal storage aggregate, Pumice stone, immersion method, phase change materials, paraffin wax.
A. THOMAS EUCHARIST, V. REVATHI
Rezumat
Concrete is one of the most vital building materials next to the water. Day by day, the demand for concrete is escalating with the rising demand for infrastructural development, and the cement industry is one of the dominant contributors to the production of greenhouse gases. So, efforts are essential to make concrete further eco-friendly by adopting cement-free concrete, which helps overcome global warming. In this study, varying compositions of alumina silica materials made up of ground granulated blast furnace slag (GGBFS) and sugarcane bagasse ash (SBA) were supposed to be utilized in the manufacture of geopolymer mortars, and five different ratios of 100:0, 75:25, 50:50, 25:75, 0:100 were proposed. It might be a better solution for both waste disposal problems and issues related to cement production. Combinations of GGBFS and SBA were made with varying concentrations of alkaline solution starting from 10M, 12M, and 14M. The strength properties of the prepared specimens were assessed by conducting compressive strength test on mortar and concrete specimens at 3 days, 7 says, 28 days. Despite the fact that not all of the combinations of the mixes examined had statistically significant results, the test results do suggest that the GGBFS-SBA blend is viable for use in geopolymer. In a 14M geopolymer concrete mix consisting of 100% GGBS, the highest compressive strength of 61 MPa was achieved.
Cuvinte cheie
Cement-free concrete, Geo polymer mortar, GGBFS, Bagasse ash, Alkaline solution
SALEM MERABTI, LAYACHI GUELMINE, MEZIANE KACI
Rezumat
This study investigates the seismic performance of reinforced concrete buildings ranging from 5 to 20 stories using nonlinear static pushover analysis. Four shear wall bracing configurations are considered: L-shaped peripheral walls, central core, double central core, and double peripheral core systems, with wall thicknesses of 15, 20, and 25 cm, all subjected to unidirectional lateral loading. Although these configurations are widely implemented in both moderate and high seismicity regions, few comparative studies have assessed their nonlinear seismic resistance. The results indicate that central core configurations provide superior control of inter-storey drift, with a significant reduction in lateral displacements—up to 48% compared to peripheral wall systems. In contrast, peripheral wall systems exhibit higher drift demands, reaching a maximum of 0.124% for 15 cm thick walls. The analysis also highlights the effectiveness of L-shaped walls in mid-rise buildings, particularly those with wall thicknesses of 20 and 25 cm. The study of deformation mechanisms reveals a concentration of plastic hinges and thus stress in L-shaped wall systems and at beam-wall joint regions.
Cuvinte cheie
Clădire cu mai multe etaje, Analiză neliniară de tip pushover, Perete de forfecare din beton armat, Derivă interetajată, Tensiune de forfecare, Moment de răsturnare.
ALI SABERI VARZANEH, MAHMOOD NADERI
Rezumat
In concrete design, durability is as vital as strength, especially in aging structures exposed to harsh environmental conditions. Increased permeability over time compromises structural integrity. Polypropylene (PP) fibers help limit cracking, which in turn reduces permeability. Traditionally, assessing permeability requires destructive core sampling. This study introduces a novel approach—the “cylindrical chamber” test—to evaluate permeability directly on structures. Validation of this method confirmed its reliability. Results indicated that incorporating PP fibers reduced permeability in C25, C35, and C45 concretes by 22.5%, 20.2%, and 16.3%, respectively. XRD analysis revealed that PP fibers influenced Ca(OH)₂ crystallization and enhanced C-S-H formation. MIP results showed a 24.5% increase in pore volume and 32.8% rise in pore surface area in C45 concrete with fibers, yet overall permeability declined. This confirms the effectiveness of PP fibers in improving durability without the need for invasive testing.
Cuvinte cheie
Beton, durabilitate, fibră, rezistență, metodă inovatoare.
KARTHIKEYAN R, PARTHEEBAN P, THOLKAPIYAN.M, SIVAKUMAR, SUGUNA K, GAAYATHRI KK
Rezumat
This work discusses the outcome of Finite Element Analysis using ANSYS Workbench, to analyse the cyclic behavior of rubberized concrete beams with steel fiber reinforcement. The investigation focuses on substituting coarse aggregate with sand coated rubber shreds, obtained from waste conveyor belt, with the sand coating applied using resin. The study examines rubber shreds in proportion of 2.5%, 5% and 7.5%, combined with steel fibres at volume fraction of 0.5% and 1%, total of seven beams were cast and tested under cyclic loading in a standard loading frame of 500kN capacity. The FEA outcomes revealed that reinforced concrete beams with steel fibres and sand coated rubber shreds reveal boosted cyclic efficiency regarding number of cycle’s sustained, maximum deflection and total energy absorption capacity. Load – deflection curves were plotted to compare experimental and FEA for all seven beams. These results have proved very helpful for better understanding the rubberized concrete with fiber reinforcement under cyclic loading, for its use in structural applications.
Cuvinte cheie
Fâșii de cauciuc acoperite cu nisip, deformare maximă, fibră de oțel, absorbție de energie și curbă sarcină-deformare.
SALEM MERABTI, KACI MEZIANE, SLIM ROUABAH
Rezumat
This study proposes a robust modeling approach for predicting the drying shrinkage of cementitious composites incorporating expanded cork waste, using a multilayer perceptron (MLP) artificial neural network. An original database consisting of 54 experimental samples and 2430 shrinkage measurements representing nine different material formulations with varying cork, sand, and ground granulated blast furnace slag (GGBFS) contents was used for model development. Five key variables describing material composition, curing conditions, and mass loss served as model inputs. After data normalization and rigorous cross-validation, the MLP significantly outperformed a classical second-degree polynomial regression, as evidenced by a coefficient of determination of R² = 0.999 and a mean absolute percentage error below 1%. Sensitivity analysis identified curing age and mass loss as the most influential factors governing shrinkage evolution, ahead of the cement-to-cork ratio, sand, and GGBFS content. These findings underline the suitability of neural network models for capturing the complex, nonlinear behaviors of bio-based cementitious materials and provide valuable insights for optimizing the design of durable, sustainable composites.
Cuvinte cheie
Plută expandată reziduală, nisip de râu, zgură granulată de furnal măcinată (GGBFS), compozit, contracție, rețele neuronale artificiale (ANN)
CHENKANG LIU, SONGLIN YUE
Rezumat
Steel fiber reinforced reactive powder concrete (RPC), as a critical material for engineering construction, has garnered significant research interest regarding its mechanical properties. This study investigates the reinforcement mechanism of steel fibers and the dynamic mechanical behavior of RPC. Composite material theory was employed to analyze the steel fiber strengthening and toughening mechanisms. The distribution of steel fibers and the microstructure of the cement matrix were characterized using X-ray computed tomography (CT) scanning and microstructural analysis. Furthermore, dynamic compression experiments were conducted to evaluate the mechanical response of RPC under high-strain-rate conditions. Results indicate that the interfacial bonding properties between steel fibers and the cement matrix substantially influence the mechanical performance of RPC. A uniform, disordered distribution of steel fibers was found to enhance both the isotropy and compressive strength of the composite. The dynamic strength demonstrates a pronounced strain-rate dependency, wherein the dynamic compressive strength and damage severity increase with escalating strain rates. Notably, damage evolution laws during dynamic compression were quantitatively characterized through high-speed camera imaging. These findings provide valuable insights into the reinforcement mechanisms of steel fibers in RPC composites.
Cuvinte cheie
beton reactiv cu pulbere; caracterizare microscopică; proprietăți mecanice dinamice; armătură cu fibre de oțel; evoluția deteriorării
BALÁZS CSABA-FÜLÖP, DRAGOȘ UNGUREANU, GAVRIL KÖLLÖ, NICOLAE ȚĂRANU, GAVRIL HODA, TUDOR-CRISTIAN PETRESCU
Rezumat
Prezenta lucrare investighează performanța structurală și durabilitatea in-situ a solurilor stabilizate, utilizate ca straturi de fundare la drumurile cu trafic redus și mediu. Două studii de caz din România (județele Mureș și Cluj) au presupus stabilizarea unor soluri argiloase slabe cu lianți hidraulici, cu scopul de a îmbunătți capacitatea portantă și comportarea în timp. Au fost efectuate evaluări de laborator și in-situ, inclusiv testări la compresiune (RC₇, RC₂₈), deflecții cu grinda Benkelmann și evaluări la cicluri de îngheț-dezgheț, în conformitate cu standardele naționale (STAS 10473-1-87, STAS 1709, PD 177, CD 31). Rezultatele indică faptul că aceste soluri, stabilizate corespunzător, pot atinge rezistențe la compresiune și module de rigiditate comparabile cu materialele granulare convenționale. Valorile deflecțiilor Benkelman și variabilitatea acestora au rămas în limitele permisibile pentru straturile de fundare, în timp ce evaluările la îngheț-dezgheț au confirmat durabilitatea materialului. Dimensionarea structurală bazată pe PD177 a arătat că straturile stabilizate pot acomoda cerințele de trafic proiectate (Nc = 0.5 milioane axe standard) cu reserve semnificative la oboseală. Acest studiu susține folosirea controlată a solurilor stabilizate în construcția de drumuri, permițându-se astfel folosirea materialelor disponibile local, reducând dependența de aggregate de carieră și susținând practicile inginerești sustenabile, aliniate cu principiile de economie circulară.
Cuvinte cheie
stabilizarea solului, straturi de fundare ale drumului, deflecție grindă Benkelmann, lianți hidraulici, construcție sustenabilă de drumuri
JEBA JENKIN JEBAMONY, ANUSHA GURURAJAN, KRISHNA PRAKASH ARUNACHALAM
Rezumat
The significant environmental impact of cement production, particularly its contribution to CO₂ emissions, has driven the search for sustainable alternatives in the construction industry. Alccofine, a byproduct of ground granulated blast furnace slag, offers a promising solution as a supplementary cementitious material (SCM). This study evaluates the mechanical and durability properties of concrete incorporating alccofine as a partial replacement for cement, emphasizing its potential to enhance sustainability in construction. Alccofine, with its ultra-fine particles and unique chemical composition, improves hydration kinetics and pozzolanic reactions, resulting in better workability, and decreased permeability in concrete. Experimental investigations reveal that up to 30% replacement of cement with alccofine yields enhanced strength without compromising concrete structural integrity. Microstructural analysis highlights the role of alccofine in refining pore structure and promoting the formation of calcium-silicate-hydrate (C-S-H) gel. By utilizing an industrial waste material, this study demonstrates a sustainable approach to mitigating environmental impacts while maintaining high-performance concrete.
Cuvinte cheie
Alccofine, ciment Portland obișnuit (OPC), înlocuitor de ciment, rezistență la compresiune, proprietăți proaspete, emisie de CO2
IVANKA DIMITROVA
Rezumat
Objective: The heat production and transfer to the dental pulp can result from various dental procedures such as friction during cavity preparation without water cooling, bleaching, applying lasers and exothermic reactions during the setting of calcium silicate cements. Calcium–silicate cements are hydraulic materials. Their setting process is associated with temperature changes in the cement paste. These bioactive materials have a variety of uses in endodontics such as a repair perforation material, retrograde root filling material and pulp preservation material. Calcium–silicate cements such as direct pulp capping agents are in direct contact with exposed vital pulp . Excessive heat production during the setting of these materials could lead to serious irreversible pulpal damage. The aim of this study was to record variations in temperature changes during the setting process of conventional calcium silicate cements. Materials and Methods The subjects of this study are three commercially-available in the dental practice calcium silicate cements: White MTA-Angelus (Angelus, Londrina, Brazil), White ProRoot MTA (Dentsply, Tulsa, Johnson City, TN), BioAggregate (InnovativeBioceramix, Vancouver, Canadа) and one industrial Portland cement..For this study thermovision camera FLIR T620 and the Flir Reporter Professional 2013 software were used.Thermal imaging capture was carried out under the following conditions: Distance from the camera lens to the experimental set -1 meter, Room Temperature – 20 - 22 degrees Celsius.Statistical Analysis The mean values of the data were compared using the Student t test. Results: The maximum average temperatures during the cement hydration process range between 26.20 and 26.80 degrees. The highest rise in temperature peak was observed with Bioagreggate at 3 minutes after starting the setting process and the warming peak after 7 minutes at ProRoot. WMTA Angelus exerts the lowest mean temperature rise. Conclusion: The knowledge of temperature rise during the setting reaction of conventional calcium silicate cements can help the dentist to make the right decision and choice of the type of calcium silicate cements. During the dental cement hydration process a rise in temperature up to 2 degrees was recorded. This difference is considered insignificant in the alteation of dental pulp and hard dental tissue.
Cuvinte cheie
Cimenturi cu silicat de calciu, schimbări de temperatură, proces de hidratare, material de acoperire directă a pulpei
LARISA PURDEA, CARMEN OTILIA RUSĂNESCU, GIGEL PARASCHIV, SORIN ȘTEFAN BIRIȘ, SABRINA-MARIA BĂLĂNESCU
Rezumat
În această lucrare am evidențiat rezultatele cercetării privind proprietăți fizice și chimice ale cenușii obținute în urma procesului de incinerare a nămolului de epurare și potențialul său de utilizare în compoziția cimentului. Având în vedere obiectivele climatice stabilite pentru 2030 și 2050, este esential ca economia circulară să fie implementată pentru cât mai multe categorii de deșeuri. În acest scop, în cadrul acestei lucrări este analiza cenușa, având cod de deșeu 19 01 14, obținută în urma incinerării nămolului de epurare ape uzate municipale și pluviale din București, în vederea utilizării în industria cimentului. Lucrarea cuprinde date statistice privind cantitatea de nămol generată în anumite țări, rezultate experimentale privind proprietățile cenușii și impactul asupra rezistențelor mecanice ale cimentului.
Cuvinte cheie
cenușa din nămol de epurare ape uzate, nămol de epurare ape uzate, ciment, deșeu.