english DOREL RADU, ZENO GHIZDAVET
Rezumat
Compoziția mineralogică a clincherului are o importanță majoră în determinarea performanțelor acestuia, inclusiv a produsului final, cimentul. Abordarea experimentală reprezintă calea cea mai potrivită pentru a obține compoziția mineralogică optimă însă aceasta devine prohibitivă atunci când spațiul de căutare a soluției este mare. În această direcție, tehnicile de programare matematică optimală, folosite în acest articol, pot ajuta la reducerea volumului experimental. Un beneficiu suplimentar al utilizării acestor tehnici computaționale este că acestea pot încorpora, așa cum este demonstrat aici, o serie de restricții de natură termotehnologică sau/și termotehnică. În acest articol rolul principal dintr-o serie de restricții este jucat de aptitudinea la clincherizare a amestecului de materii prime și, respectiv, de diferența de bazicitate între oxizi.
Cuvinte cheie
Compoziție clincher, optimizare, clincherizare
QINGWEI SUN , HAN ZHU, HAOYU LI, HAIYANG ZHU
Rezumat
A series of research experiments was designed and conducted in this study using the Box–Behnken design method of response surface methodology (RSM) to solve the optimization problem of parameters effectively in fly ash geopolymer concrete preparation. First, single-factor gradient analysis was adopted to determine the reasonable level of various factors in the response surface analysis. The 28-day compressive strength development was investigated in terms of the water–binder ratio, dosage of alkali, unit water dosage, and sodium silicate modulus. Results showed that the order of the factors in terms of their influence on concrete strength was dosage of alkali, sodium silicate modulus, and water–binder ratio, and the unit water dosage exerted a minimal influence. Second, the preparation parameters were optimized to improve the 28-day compressive strength of the concrete based on the single-factor analysis using the RSM. The optimum parameters were a water–binder ratio of 0.35, an alkali dosage of 7.9%, and a sodium silicate modulus of 1.66. This study also analyzed the response surface optimization results through a validation test to prove the effectiveness of the RSM in optimizing the preparation of geopolymer concrete.
Cuvinte cheie
Corelare imagine digitală, etrier dublu strat, beton, capacitate portantă, efortul de recul
XIAONIU YU , SUN LINZHU, FANG YANG
Rezumat
With a double-layer stirrup confined high-strength concrete column as study object, vertical loading experiments were conducted, and the strain field of the member during loading was measured dynamically using the digital image correlation technology. The experimental results show that, for double-layer stirrup confined high-strength concrete, the strain change differs greatly between the early and late stages of loading, being smooth in the early stage and active in the last stage. Through the analysis of the full-field strain of the member, the displacement grid diagrams and strain distribution contour plots at different stress levels were obtained. From the contour distribution was determined that, during loading, the strains in the member are different at different positions and they are also different at different time points at one position. There is a stress concentration area during loading, where a “strain rebound” phenomenon occurs after the stress reaches its peak. The strain calculation results also reveal that selecting different areas for calculation will have large influence on the calculation results regarding the overall strain of the member. In addition, the experiments also indicate that, due to its non-contact and full-field features, the digital image correlation technology is suitable for dynamic measurement of structural force, and it is a powerful means for deformation detection and health monitoring of a structure.
Cuvinte cheie
Corelare imagine digitală, etrier dublu strat, beton, capacitate portantă, efortul de recul
A.SUMATHI , K. GOWDHAM , K. SARAVANA RAJA MOHAN
Rezumat
The study of High Strength Concrete (HSC) has become interesting as concrete structures grow taller and larger. The usage of HSC in structures has been increased worldwide and has begun to make an impact in India. Ordinary cementitious materials are weak under tensile loads and fiber reinforced cementitious composites (FRCCs) have been developed to improve this weak point. Specimens such as cubes, cylinders were cast for High Strength concrete containing Alccofine as mineral admixture and reinforced with micro steel fibers to study the mechanical and durability properties at 28 days and 56 days of curing. The concrete were designed to have compressive strength of 60 MPa. Mixtures containing 0% and 10% replacement of cement by Alccofine and with 1%, 2% and 3% of micro steel fibers by weight of concrete were prepared. Durability properties such as Sorptivity, water absorption, resistance against Sulphuric acid, Sodium sulphate and Magnesium sulphate were studied for control, Alccofine and Alccofine with steel fibers for different days of curing. Mixtures incorporating Alccofine with fibers developed marginal increase in strength and durability properties at all ages when compared to control concrete.
Cuvinte cheie
HSC, alcofine, microfibre de oțel, durabilitate, rezistență la acid sulfuric și sulfați
MALHEIRO RAPHAELE, AIRES CAMÕES, GIBSON MEIRA
Rezumat
To ensure the durability of concrete structures it is necessary to understand its behaviour in the presence of aggressive agents. Carbonation and chloride ingress are the two main causes of degradation in reinforced concrete. The combination of these factors can create a very harsh environment for concrete structures. Given the importance of chloride migration coefficient for areas such as service life prediction, this work intends to study the influence of carbonation on the chloride migration coefficient of ordinary Portland cement (OPC) concrete. Concrete specimens were cast with different water cement ratios: 0.4, 0.5 and 0.6. After 90 days of curing, half of samples were subjected to carbonation chamber (4% CO2, 20 ºC and 55% RH) for 6 months. The other half was protected with plastic sheet during the same period. Non-steady-state migration test was performed in specimens with and without exposure to carbon dioxide environment. The results show that, for these conditions, the carbonation has a direct influence on chloride diffusion coefficient, increasing it. The carbonated samples studied showed a chloride migration coefficient up to 130% higher than noncarbonated ones. This fact can be related to the reduce in chloride binding capacity caused by carbonation front.
Cuvinte cheie
Cloruri, încercare de migrare, carbonatare, beton, acțiune combinată
YAO YAN , TANG GUANBAO, WANG LING, CUI SUPING, CAO YIN
Rezumat
In this study, the effect of CO2 concentration on carbonation depth, semi-carbonated zone, pore size distribution and carbonation products in concrete were investigated. The CO2 concentration was increased from 0.035 % to 2 % and 20 % at 70 % relative humidity and 20 °C. The results show that the carbonation process of 2 % CO2 was more similar to natural carbonation than 20 % CO2, as evidenced by the better linearity fitness of carbonation depth. The length of semi-carbonated zone was 6 mm at 2 % CO2 and 8 mm at 20 % CO2 within 16 weeks, a number that cannot be ignored when predicting the service life of concrete under carbonation. CH remained in a small amount in the completely carbonated zone instead of being completely consumed, and CH consumed at 20 % CO2 is about 1.5-2.0 times that of 2 % CO2. The content of CaCO3 in the completely carbonated zone at 20 % CO2 was higher than that of 2 % CO2. CaCO3 could fill in large pores between hydration products, so the porosity, average pore size and aperture decreased with CO2 concentration.
Cuvinte cheie
Carbonatare beton, concentrație CO2, adâncime de carbonatere, produse de carbonatare
ILDIKÓ ANGER, ENIKÖ VOLCEANOV, GEORGIANA PLOPEANU, LEONARD ILIE, LAVINIA GABRIELA POPESCU, GEORGIANA ALEXANDRA MOISE
Rezumat
Lucrarea prezintă cercetări privind potenţialul utilizării zgurii LF în agricultură, ca amendament al solului. Zgura LF rezultă la rafinarea oţelului in procesele metalurgiei secundare. Principalele componente ale zgurii LF utilizate în studiile noastre experimentale au fost: CaO, SiO2, Al2O3, MgO. Zgura LF conţine o cantitate semnificativă de CaO care formează diferiţi compuşi cu SiO2 şi Al2O3, alături de CaO nereacţionat. Acesta este principalul motiv pentru care această zgură poate fi considerată în agricultură drept amendament al solului in sensul corectării acidităţii solului. Aciditatea solului influenţează fertilitatea acestuia şi producţia culturilor. De obicei, aciditatea solului este corectată prin utilizarea unor materiale naturale, cum ar fi calcarul sau dolomita. Utilizarea zgurii LF ca amendament al solurilor acide este o noutate în România.
Se prezintă influenţa amestecului de zgură LF asupra remedierii solului, şi anume asupra pH-ului, proprietăţilor chimice şi conţinutului de metale grele. De asemenea, este prezentată influenţa utilizării zgurii LF ca amendament al solului asupra producţiei agricole şi asupra conţinutului de metale grele din sol şi din plantele cultivate (porumb, grâu şi soia) pe loturile experimentale. Experimentele au indicat faptul că zgura LF poate fi utilizată pentru remedierea solurilor acide, aceasta având o influenţă benefică atât asupra proprietăţilor chimice ale solului, cât şi asupra creşterii producţiei agricole.
Cuvinte cheie
Procese metalurgice, zgură de furnal, soluri acide, amendament pentru sol
RĂZVAN LISNIC, SORIN ION JINGA
Rezumat
Combustibilii fosili utilizaţi în termocentrale, conţin cantităţi semnificative de sulf. La ardere, aproximativ 95% din cantitatea de sulf se transformă în dioxid de sulf (SO2) care, reacţionează cu particulele de apă din atmosferă, formând ploi acide în condiţii normale de temperatură şi presiune. Dioxidul de sulf, prin cantităţile anuale emise în atmosferă, este principalul poluant gazos, motiv pentru care există de peste 80 de ani o preocupare pentru elaborarea și eficientizarea proceselor de desulfurare. Procesul de desulfurare a gazelor de ardere se poate realiza atât pe cale umedă, cât și uscată. Cel mai răspândit procedeu este desulfurarea umedă a calcarului sau varului, reprezentând circa 85% din totalitatea procedeelor de desulfurare. Lucrarea prezintă situația curentă a tehnologiilor de desulfurare din lume, avantajele și dezavantajele acestora, cât și tendințele viitoare din acest domeniu.
Cuvinte cheie
Calcar, desulfurare gaze de ardere, SO2, FGD – gips, cenușă de termocentrală
SEBASTIAN MARIAN ZAHARIA, CRISTIN OLIMPIU MORARIU, MIHAI ALIN POP
Rezumat
Panourile sandwich sunt frecvent utilizate ca elemente structurale în diverse aplicații industriale, datorită rigidității lor ridicate în raport cu greutatea, dar și a avantajelor pe care le conferă în comparație cu structurile metalice convenționale sau cu structurile compozite laminate. Lucrarea prezintă comportamentul în regim static și la oboseală a două structuri sandwich cu același tip de miez fagure Nomex, dar cu învelișuri din compozite polimerice armate cu fibre de sticlă, fabricate prin metode diferite. De asemenea, au fost comparate și analizate caracteristicile mecanice pentru cele două tipuri de structuri sandwich. În cadrul acestei lucrări a fost descris și prezis comportamentul la oboseală ciclică a celor două structuri sandwich, supuse la încovoiere în 3 puncte, prin implementarea tehnicilor de testare accelerată. Această metodologie accelerată, dezvoltată în această lucrare, a determinat o reducere semnificativă a timpului de testare pentru specimenele analizate. Astfel, timpul de testare a fost redus de 6.35 ori pentru specimenele GFRP1-Nomex și respectiv cu 7.9 pentru specimenele GFRP2-Nomex, ceea ce determină o scădere semnificativă a costurilor privind testarea structurilor sandwich compozite. De asemenea, au fost identificate și analizate principalele moduri de defectare ale structurilor sandwich, supuse la impact Charpy, utilizând analiza microscopică.
Cuvinte cheie
polimeri armați cu fibră de sticlă, panouri sandwich, încovoiere, oboseală, încercare accelerate
LINO BIANCO
Rezumat
The Lower Globigerina Limestone Member, the earliest member of the Globigerina Limestone Formation, is the lithostratigraphical bed which had provided limestone for the erection of Malta’s built heritage since Neolithic times. It is massively bedded, pale yellow in colour and consists predominantly of globigerinid planktonic forminifera. Occasionally, blue coloured lenticular patches occur in this member. The first published research relating to these features was by John Murray in 1890. His results and interpretation were corroborated and refined through a recent publication by the author which noted variations from packstone to wackestone along these patches. This paper further studies their petrological characteristics. Petrographically, the limestone of these patches gradually alternates from wackestone to mudstone to bioclastic wackestone. They are composed of micrite matrix (in varying amounts), ferrugenized unbroken pelagic foraminifera, bioclasts, and terrigenous quartz. The appearance of these blue lenticular patches must be linked to another process other than limestone texture.
Cuvinte cheie
Calcar Globigerina, pete albastre, clădiri Malta
CRISTINA DIMA (VĂDUVA), ALINA BĂDĂNOIU, ȘTEFANIA STOLERIU, CRISTIANA DANEȘ
Rezumat
Valorificarea deșeurilor industriale în producerea materialelor de construcție reprezintă o temă de studiu de mare actualitate.
Prezentul studiu își propune îmbunătățirea proprietăților de izolare termică ale unor compozite pe bază de ipsos, prin substituirea parțială (5% și 30% procente gravimetrice) a acestuia cu deșeuri industriale (poliuretan, cauciuc și cabluri electrice tocate). De asemenea, s-a urmărit și influența pe care aceste deșeuri o exercită asupra unor proprietăți specifice pentru materialele de izolație termică (conductivitate termică, rezistența la compresiune și absorbţia apei prin imersie parțială de scurtă durată ).
S-a constatat că utilizarea acestor deșeuri industriale în compoziția plăcilor de ipsos determină o îmbunătățire a proprietăților de izolare termică (conductivitatea termică scade cu 17-23%) corelată însă cu o scădere a rezistenței mecanice cuprinsă între 68-87%.
Producerea acestor materiale de izolație poate contribui la rezolvarea unor probleme de mediu, prin reducerea cantității de materii prime naturale folosite și utilizarea unor deșeuri ca materii prime alternative.
Cuvinte cheie
materiale temoizolante, ipsos, deșeu industrial, conductivitate termică, proprietăți
N. KYBARTIENĖ, D. NIZEVIČIENĖ, Z. VALANČIUS, G. VAICKELIONIS
Rezumat
Gypsum raw material (reagent gypsum, phosphogypsum and processed phosphogypsum) was dehydrated by dry method (i.e. in dry air environmental) and wet method (i.e. saturated water vapour environment) using microwaves. Influence of dehydration method on hemihydrate gypsum, hemihydrate phosphogypsum and processed hemihydrate phosphogypsum crystal morphology was researched. Gypsum raw material dehydration in dry air environment using microwaves does not significantly influence the morphology of hemihydrate gypsum, hemihydrate phosphogypsum or processed hemihydrate phosphogypsum crystals. Meanwhile, when raw material is dehydrated in the saturated water vapour environment using microwaves, the produced product crystals are smaller comparing to crystals of products dehydrated without microwaves. Therefore, it may be stated that using microwaves for gypsum raw material dehydration has no positive effect on the morphology of the obtained product crystals
Cuvinte cheie
Gips, fosfogips, dehidratare, microunde, cristale
YAOHUI MA, DEZHI ZHAO, LIN CHI, ZHENG WANG, YAN YAO, SHUANG LU
Rezumat
In this numerical study, finite element method (FEM) is employed to demonstrate temperature and stress simulations of autoclaved aerated concrete (AAC) shear walls in different seasons by using ANSYS software. Structural behavior simulation is conducted by a good combination of comprehensive material properties and reasonable models. Calculation results show that, compared with the ordinary mortar (OM), the insulation mortar (IM) can effectively reduce f temperature variation in AAC matrix layer by 1.668℃ in summer and 5.315℃ in winter, which indicates a better performance on heat insulation. In terms of thermal stress, IM layer would withstand a greater stress in all cases, but it could lower the maximum stress in AAC layer and interface stress by almost 50% in winter compared with wall structures with OM. As for temperature deformation, a 17% reduction in winter and a 30% reduction in summer are observed in AAC matrix layer coated with IM.
Cuvinte cheie
Metoda elementelor finite (FEM), panouri din beton celular autoclavizat, efort termic, temperatură de deformare
JUAN HE, JUN CAI, ZHENMAO SUN
Rezumat
Hydration Characteristics of alkali–activated slag cement (AASC) are different of those of ordinary Portland cement. Effects of activator type, modulus of water glass (WG), and Na2O equivalent on setting time, compressive strength, hydration heat and hydration products were studied. The results show that with the increase of modulus in the range of 0.8-2.0, initial and final setting time of AASC extends gradually. As for hydration heat, When WG modulus increases from 0.8 to 2.0, the first combined peak of AASC grows lower and grows a bigger diffusion; accelerated hydration peak appears later; induction period prolongs and cumulative hydration heat reduces. When Na2O equivalent increases from 3% to 6%, for WG-activated slag, the first peak and accelerated hydration peak appear earlier and higher, induction period becomes shorter and setting time of paste is somewhat longer. Besides, for NaOH (NH)-activated slag, initial peak and accelerated hydration peak appear earlier and higher and setting time of paste is shorter. Cumulative hydration heat of both AASC increases with the increase of Na2O equivalent. At the same Na2O equivalent, setting time of slag activated by NaOH is longer than WG-activated slag cement, and compressive strength of the former is lower than the later. In the range of 0.5-2.2, with the increase of modulus, compressive strength of AASC first increases, then was followed by a decrease. The main hydration product is C-A-S-H gel.
Cuvinte cheie
Ciment cu zgură activat alcalin, activator, căldură de hidratare
NAILIA R. RAKHIMOVA, RAVIL Z. RAKHIMOV, YEVGEN S. LUTSKIN, VLADIMIR P. MOROZOV, YURI N. OSIN
Rezumat
In this study, a mineral matrix based on alkali-activated slag cement (AASC) was found to be suitable for solidification of up to 35% (by volume) of borate ion-exchange resins (IERs) at pH values of 8.5 to 10.5. Experimental-statistical modelling, X-ray diffraction, and scanning electron microscopy/energy dispersive spectroscopy analyses were used to study the waste samples. According to the results of a four-factor experiment, the strengths of waste samples based on AASC-based mineral matrices and borate IERs were mostly determined by the nature of the alkali component and the pH of the borate IERs. The strengths of the waste samples could be improved by some modifications of the binder material - increasing the Na2O concentration and introducing polypropylene fibres. The main reaction products in the (GGBFS)-(sodium metasilicate, sodium hydroxide)-(borate solution) system were C-(A)-S-H, calcite (CaCO3), hydrotalcite (MgO6.667Al0.333)(OH)2(CO3)0.167(H2O)0.5, calcium silicate hydrates
Cuvinte cheie
Ciment cu zgură activat alcalin, modelare, deșeuri de rășini schimbătoare de ioni, rezstență la compresiune, încercare calorimetrică
DAN GEORGESCU, LAURENȚIU RECE, BIANCA PIRONEA, ADELINA APOSTU
Rezumat
Prezentul articol propune o metodologie de evaluare a caracteristicilor betonului plecând de la analiza punctelor critice generate de specificul lucrărilor care devin ascunse. Se prezintă o nouă abordare față de cea existentă și se exemplifică printr-o aplicație pentru evaluarea rezistenței betonului din construcțiile nou executate. Aplicarea metodei se bazează pe cele mai recente propuneri de revizuire ale unor reglementări specifice europene.
Cuvinte cheie
Beton, rezistență, evaluare, metodologie
CAI JUN, LI GENGYING, ZHAO XIAOHUA
Rezumat
As an advanced construction material, self-consolidating concrete (SCC) is a highly flowable concrete that is able to fill the formwork under its own weight without vibration. This paper presents a study on fatigue performance of SCC under flexural load. An experimental program has been carried out to investigate the fatigue lives of SCC for various levels of the fatigue stress. The fatigue tests on SCC beam specimens (100 × 100 × 400 mm) were conducted. The fatigue test data of SCC is used for regression analysis. The results indicate that the flexural fatigue life distribution of SCC approximately follow the double-parameter Weibull distribution. The regression parameters of the fatigue equation corresponding to different survival probabilities have been obtained. The flexural fatigue strength of SCC for the desired level of survival probability can be estimated by using the fatigue equation.
Cuvinte cheie
Beton autocompactant, oboseală, sarcină flexivă, nivel efort
V. KARTHIKA, P. O. AWOYERA, I. I. AKINWUMI, R. GOBINATH, R. GUNASEKARAN, N. LOKESH
Rezumat
This study investigates the structural properties of lightweight self-compacting concrete produced using mineral admixtures and pumice stone as aggregate. Lightweight self-compacting concrete (LWSCC) mixes were prepared using pumice stone as replacement for natural coarse aggregate, and ground granulated blast furnace slag and rice husk ash were added as mineral admixtures. The flowability of the concrete mixtures was achieved by using gelinium B223 super plasticizer. Structural properties such as: density, compressive strength, flexural strength, and split-tensile strength of the concrete samples were determined for different mix proportions. Test results revealed that 30-40% replacement of coarse aggregate by pumice stone is considerable for improved density, compressive strength, split tensile strength and flexural strength development in LWSCC
Cuvinte cheie
Beton autocompactant, piatră ponce, beton ușor, adaos mineral, superplastifiant
G. MURALI, K. KARTHIKEYAN, M.K. HARIDHARAN
Rezumat
In this paper, the impact strength of four concrete mixtures namely green high performance plain concrete (GHPPC), green high performance and steel fibre reinforced concrete (GHPSFRC) subjected to drop weight test was statistically investigated. The steel was incorporated each at a dosage of 0.5%. The pre-determined green concrete mixtures were prepared with 2% of nano silica as cement replacement and 30% of copper slag as fine aggregate replacement. From each type, 40 specimens were tested using the drop weight test in accordance with procedure proposed by ACI Committee 544 and their impact strength was determined. Results showed that the distribution of impact strength of GHPPC and GHPSFRC were approximately normal. The minimum number of tests necessary for attaining the impact failure strength of, GHPPC and GHPSFRC specimens were found to be 57 and 41 respectively at 95% level of confidence with an error below 10%.
Cuvinte cheie
Beton autocompactant, piatră ponce, beton ușor, adaos mineral, superplastifiant
LING QIN , XIAOJIAN GAO, HUAN YE, TIEFENG CHEN
Rezumat
This paper aims to investigate effects of anti-foaming admixture (AFA) on air content, flowability, mechanical strength and microstructure of ultra-high performance concrete (UHPC). UHPC mixtures were prepared with two water-binder ratios of 0.17, 0.2 and three AFAs (XP1, XP2, XP3) were added by 0.05-0.4% of the mass of binder. Results reveal that the air content of fresh UHPC mixture decreases whit the incorporation of AFA and XP1 behaves the best decreasing effect. The compressive strength of UHPC added with AFA is increased and XP2 presents the best effect. The decrease of water-binder ratio from 0.2 to 0.17 doesn’t lead to an increase in compressive strength due to the more air bubbles entrapped in very low water-binder ratio mixture. A good exponential relationship (f=a*x^b) can be found between compressive strength and entrapped air content. The incorporation of AFA decreases the coarse pore content (＞100nm) and air bubbles with diameter bigger than 100μm in hardened specimen, playing a positive role in optimizing pore structure and improving strength.
Cuvinte cheie
Beton de ultra înaltă performanță, lucrabilitate, rezistență la compresiune, distributie granulometrică, adaos antispumant
SADIK ALPER YILDIZEL
Rezumat
Fiber reinforced composites have been widely used for various building purposes. Glass fiber reinforced composite containing white cement, gypsum, silica sand and perlite were analyzed in this research. The flexural strength, shrinkage behavior and the freeze-thaw (F&T) resistance of the composites were examined. It was obtained that the use of expanded perlite and silica sand enhances the shrinkage properties of the composite. Especially, expanded perlite used as the replacement of silica sand at the rate of 15 % has significantly enhanced the mechanical properties of the gypsum added composites against the freeze and thaw (F&T) and the shrinkage effects. Researched composite type and the outcomes of the study can be used in the composite production industry for improving the durability and sustainability.
Cuvinte cheie
Fibre de sticlă, gips, ciment alb, compozit, nisip, perlit
IRINA ȘTEFAN (OANCEA), MARINELA BĂRBUȚĂ, MIHAI BUDESCU, PETRU MIHAI, ANA MIHAELA BANU, NICOLAE ȚĂRANU
Rezumat
Lucrarea prezintă rezultatele experimentale obținute în ceea ce privește proprietățile mecanice ale unor tipuri inovatoare de micro-beton. În acest sens, au fost preparate două rețete de beton utilizând cenușa de termocentrală ca înlocuitor a 10% din cantitatea de ciment și două tipuri de deșeuri: granule din polistiren și agregate obținute din PET-uri reciclate, adăugate în amestecuri ca substituient al agregatului natural fin (sortul 0-4 mm), în diferite proporții cuprinse între 30% și 100%.
Valorile rezistențelor mecanice (rezistența la compresiune, rezistența la întindere din încovoiere, rezistența la întindere prin despicare) determinate pe cale experimentală pentru ambele tipuri de micro-beton sunt mai mici decât cele obținute pentru rețeta martor. Curbele caracteristice complete tensiune-deformație specifică la compresiune au fost stabilite pentru a evalua capacitatea de absorbție a energiei de deformație a acestor materiale. Valorile experimentale obținute pentru rețetele de micro-beton cu agregate din PET au fost mai mari decât cele corespunzătoare rețetelor cu granule din polistiren. Prin utilizarea unor procente mai mari de substituție a agregatului natural cu materiale reciclate s-a obținut un beton ușor.
Cuvinte cheie
Cenușă de termocentrală, agregate din deșeuri PET, polistiren granulat, rezistențe mecanice, curbe complete tensiune-deformație
AYDIN RUSEN
Rezumat
High temperature crystal chemistry and thermal behavior of the boron minerals bear special attraction, owing to the increase in their application areas requiring elevated temperature. Colemanite 2CaO·3B2O3·5H2O) is one of the most commonly found and used compound among the boron minerals. In this study, therefore, thermal and mineralogical characterization of the colemanite was performed by X-ray Diffractometer (XRD) and Thermal Gravimetric Analysis (TG-DTA). Also, mineralogical changes in crystal structure were measured and recorded during heating from room temperature up to its melting temperature for each 50°C by using High Temperature XRD device. By this way, structural changes in the colemanite up to melting point were determined with increasing temperature for the first time. Results indicate that the thermal decomposition of colemanite has revealed a multi stage internal process; i) moisture removal, ii) dehydration- dehydroxylation, iii) amorphization of the crystal structure, iv) recrystallization of the amorphous solid (gradual reconstitutions).
Cuvinte cheie
Colemanite, descompunere termică, HTXRD, TG – DTA
ZHANG XIAO-NAN, SHAN REN-LIANG, QI CHENG-ZHI
Rezumat
Through the monitoring of the displacement of the middle accross section in concrete filled steel tube (CFST) arch with 0.26 rise-span ratio, which fixed at both ends under the condition of uniform loading, as well as the strain and the ultimate bearing capacity of outer steel pipe and inner core of concrete which combined with ABAQUS for simulation analysis of bending process. Meanwhile, based on the ABAQUS simulation software with cohesive elements as the main research method in the constitutive model of concrete was put forward. The actual simulating and experiment results shows that the local failure characteristics of core concrete of CFST arch is similar to those of uniaxial compression on concrete short columns, and there is only compressive stress exists among the middle accross section of CFST arch which causes the volume of the inflated burst when fixing at both ends. Moreover, there is no influence on the bearing capacity of the overall core concrete with and the load displacement curves, which proved the efficiency of the proposed method and the basis for the study of other components of CFST during the mine construction.
Cuvinte cheie
Experiment de încovoiere a arc CFST, ABAQUS, elemente coezive, model constitutive, experiment cu compresiune uniaxială
BELEBCHOUCHE CHERIF, MOUSSACEB KARIM, HAMMOUDI ABDELKADER, AMOURI CHAHINEZ
Rezumat
This article focuses on the study of the release of Pb2+, stabilized/solidified by hydraulic binder (cement CEM II-42.5) for 28 days in an acid medium. Three mortars were prepared with different percent of PbO namely 0.6, 0.96 and 1.2%. Vicat needle indicated that lead retards the hydration process of mortars compared to the control sample. In the study interval [0.6%-1.2%], the increase in the percentage of PbO in mortars decreased the mechanical strength. The release of lead during TCLP test (Toxicity Characteristic Leaching Procedure) and the effectiveness of the process of Solidification/Stabilization depended on the initial concentration of the pollutant (Pb2+), and of the time of leaching. The use of X-ray diffraction allowed the identification of the new complex crystalline phases within the structure of Stabilized/Solidified samples, namely: Pb2Al4(OH)8(CO3)43H2O and Pb(OH)2. This study was completed by modeling the experimental data which revealed that the release process is much more a surface phenomenon (dissolution or precipitation). The evaluation of degradation of samples gave no sign of any major deterioration of the stabilized/solidified materials.
Cuvinte cheie
Compus periculos (PbO), TCLP – încercare, lixiviere, XRD, modelare, degradare
GONZÁLEZ-LÓPEZ, R., DÍAZ-PEÑA, I, ZALDÍVAR-CADENA, A.A., HERNÁNDEZ-SANDOVAL, J., RANGEL-PERAZA, G, RODRÍGUEZ-MATA, A.E
Rezumat
The addition of nano-SiO2 (NS) in the mix stage of cementitious materials (CM) based in Ordinary Portland Cement (OPC) has been demonstrated as a promising approach to lead the improvement of properties such as microstructure density, hydration kinetic and pozzolanic reaction rate, which are very important parameters concerning to the structure durability. However, in the case of hardened structures, the mechanism of how NS interacted with cement matrix is limited, because most of the involved reactions have already happened. In this work, the effect of the colloidal nano-SiO2 application in the surface of an early age hardened limestone mortar is studied and a comparison between two different methods is presented: migration (by electrical field) and capillary absorption (by wet-dry cycles). Measurements of potential difference, current intensity and electrical resistance were carried out in migration cells and electrical resistance for capillary absorption cell. Optical microscopy (OM) and scanning electron microscopy (SEM) in backscattering electrons (BE) coupled with energy dispersive x-ray spectroscopy (EDS) were used to characterize the microstructure of the cement mortar samples. It was found that the nano-SiO2 penetrate the cement mortar sample by both migration and capillary absorption from the surface to the interior and interact with the phases of the cement matrix. Ca/Si rates below the conventional values of the conventional phases were found (up to 0.5), which means that an increasing of cement matrix silicon content was promoted.
Cuvinte cheie
Mortar din ciment pe bază de calcar, nano- SiO2, tratament de suprafață
N. KYBARTIENE, D. NIZEVICIENE
Rezumat
A full factorial design was employed to evaluate the hydration of anhydrite cement produced from flue gas desulfurization gypsum (FGD gypsum) using three activators (KAl(SO4)2·12H2O, Na2SO4, FeSO4·7H2O). The effect of three independent variables such as the calcination temperature of FGD gypsum (500-800oC), the hydration time (3-28 days) and the amount of activator (0-1%) on the hydration of anhydrite cement were studied. The experimental results and statistical analysis showed that the hydration time and the amount of activator had a positive effect on the hydration of anhydrite cement, while the temperature had a negative effect on this process. The multiple linear regression models were developed to correlate the significant variables to the chemically combined water content in hydrated anhydrite cement. The mean absolute percentage error between experimental and calculated values of the chemically combined water content in hydrated anhydrite cement was less than 2%.
Cuvinte cheie
Proiectare factorială, ciment anhidrid, hidratare, activatori
JUAN HE, YONGHUA WU, CHANGHUI YANG, QIE GAO, XIAOLIN PU
Rezumat
AAS binders activated by water glass (WG) and sodium hydroxide (NaOH) solution was used to investigate its carbonation properties. Carbonation product, carbonation shrinkage, and effect of carbonation on pore structure of AAS paste were studied. Compared with noncarbonated one, when AAS paste was carbonated, specific surface area and cumulative pore volume increased, and average pore diameter and most probable pore diameter reduced. As for carbonation product, the main form of CaCO3 is calcite, and the phases as vaterite and aragonite are lesser. The amount of aragonite and vaterite increases with the increase of carbonation age. During carbonation, the shrinkage only comes from the migration of Ca2+ from C-A-S-H gel and the increase of degree of polymerization (DP) of C-A-S-H gel. Carbonation process of AAS paste doesn’t increase the dry shrinkage.
Cuvinte cheie
Zgură activată alcalin, carbonatare, structura porilor, produs de carbonatare, conytacție de carbonatare
F.J. VÁZQUEZ-RODRIGUEZ, J.VALADEZ-RAMOS, R. PUENTE-ORNELAS, J.E.CONTRERAS, A.ARATO, EDÉN A. RODRÍGUEZ
Rezumat
An alternative solution to reduce environmental pollution using aluminum waste foundry sand (AWFS) and fly ash (FA) to produce sustainable construction materials was studied. New mortars were prepared by partially replacing ordinary Portland cement with fly ash at 5, 10 and 15 % mass. and a total replace of Ottawa sand (OS) with AWFS. The specimens were cured at 25°C with a 100% relative humidity. The mechanical behavior was evaluated by compression test at the ages of 7, 14 and 28 days. The microstructural characteristics were analyzed by scanning electron microscopy (SEM). The results indicate that the addition of milling fly ash in AWFS mortars increases the mechanical resistance, mostly at 5% mass reaching the maximum value of 10 MPa at 28 days of age. Microstructurally, it was found a porous cement matrix with some cracking caused by the reaction of portland cement with the metallic aluminum remaining in the waste sand, which is correlated to the low mechanical resistance obtained. The final mechanical characteristic makes this new product a serious candidate to be used as a sustainable building material working at low load.
Cuvinte cheie
Construcții, mortare, ciment Portland, cenușă de termocentrală, compozite, poluare
MAHIMA GANESHAN, DR. V. SREEVIDYA, L. NIRUBANCHAKRAVARTHY, G. SINDHU
Rezumat
This study extends the ongoing investigation on bond performance of embedded steel in self consolidating geopolymer concrete, when Class F fly ash is blended with Class C fly ash. 5% OPC and 10% Class C fly ash are replaced to the basic source material Low calcium Fly ash, to facilitate the external exposure curing conditions and thereby aiming for cast in situ concrete production. Synthesising solutions for source material used are combination of sodium hydroxide and sodium silicates. Normal self compacting concrete, Self compacting geopolymer concrete with added OPC and Self compacting geopolymer concrete with OPC and Class C fly ash are the types of concrete selected for experimental investigation. Pull out tests are carried out by varying diameter and bond length of embedded steel in concrete. Comparison of bond stress on 54 pull out specimens was determined using IS: 2770 (Part 1) and studies revealed that inclusion of Class C fly ash in self consolidating geopolymer improves the bond strength tremendously. Results were compared to the latest empirical models proposed by researchers and FIB model code 2010.
Cuvinte cheie
Beton geompolimer autocompactant, ciment Portland normal, cenușă de termocentrală clasa C, lungime de legătură, rezistență de legătură
RAYED ALYOUSEF
Rezumat
Nowadays, the construction industry over the entire world is looking for more economical construction materials. In addition, the existence of self-compacting concrete is facing brittleness problems due to their high binder content and low aggregate amount. On the other hand, the fiber is widely known to enhance the properties of concrete by bridging the crack width and hence, overcoming the brittleness problem in concrete. The goal of this paper is to evaluate the effect of different fibers on the properties of self-compacting concrete such as stand chopped basalt (SCB) and polyvinyl alcohol (PVA) fibers. The experimental work conducted were fresh tests, such as slump flow, slump T50 and V-funnel, while the hardened properties were compressive, flexural and bond strength. The results gathered from the empirical work showed that the fibers had a slight effect on the fresh properties and the compressive strength. While the flexural and bond strengths increased with the addition of the fiber content.
Cuvinte cheie
Beton autocompactant, fibre de bazalt tăiate, polivinil alcool, încercare în stare proaspătă și întărită
NANDHINI. K, PONMALAR. V
Rezumat
The main constituent of concrete is cement which has a noteworthy negative ecological issue causing colossal CO2 commitment amid the concrete creation. This cement content should be replaced with by-products like Micro-Silica (MS) in order to prevent the greenhouse effect to some extent. This study examines the penetrating response of Self-compacting concrete (SCC) made of micro-silica as partial cementitious replacement material. The utilization of micro-silica in varying percentage like 5%, 10% and 15% along with the appropriate dosage of chemical admixtures were experimentally investigated. This concrete proportion was tested for fresh properties like slump flow, J-ring test and U-Box test. The split tensile strength of SCC was determined at the age of 28 and 90 days. The water permeability properties like saturated water absorption, sorptivity, porosity were conducted on hardened concrete. The rapid chloride penetration test was conducted to evaluate the amount of charge passed in concrete. These results revealed that the replacement level of cement by optimized proportion of 10% MS improved the workability to 3.8%, the tensile strength to 22.82% and enhanced the durability properties.
Cuvinte cheie
Micro-silice, capacitate de curgere, absorbție apă, sorbție, penetrare cloruri
BIN LUO, WEI HUANG
Rezumat
This paper aims to disclose the bending properties of composite slab and base slab made from recycled concrete. For this purpose, our research group created haydites from underground sludge and discarded bricks, and mixed them with steel fibres into steel fibre-reinforced recycled haydite concrete (Concrete A) and steel fibre-reinforced recycled brick concrete (Concrete B). Then, each of the two recycled concretes was casted into a rectangular-finned prefabricated (RFP) base slab, which is known for its excellent rigidity, strong bearing capacity and large contact area. For comparison, another RFP base slab was made from ordinary concrete. After that, ordinary concrete was poured onto the three RFP base slabs, forming three composite slabs. Next, static load tests were performed on full-size specimens on all three RFP base slabs and three composite slabs. Based on the test results, the failure features of the specimens and the synergic effect between old and new concretes were discussed in light of the load-deflection curves, load-bar strain curves, contact area between base slab and upper-layer concrete, load-compressive strain curves and feature parameters. It is concluded that under static vertical load, the base slabs and composite slabs made from recycled concretes shared the same failure process with those made from ordinary concretes; the old and new concretes exhibited excellent bonding and synergic effects; the base plate made from Concrete B boasted the highest bearing capacity and lowest deflection among all base plates and composite plates investigated in our research. The research findings lay a solid basis for the research and application of recycled concrete composite slabs.
Cuvinte cheie
Aggregate reciclate, proprietăți de întărire, placă de bază prefabricată dreptunghiulară cu aripioare
XIAO-YING LIANG, DONG-XIA YUAN, JUN LI, CHANG-LONG WANG, XIAO-RAN LIN, NING CHANG
Rezumat
Based on the background that large amount of iron ore tailings (IOT) are stockpiled in China, the utilization of iron ore tailings to prepare autoclaved aerated concrete (AAC) was studied. The AAC samples were prepared on a laboratory scale with with a bulk density of 588 kg·m-3, compressive strength of 4.82 MPa, and thermal conductivity of 1.50 W/(m·K) which was in line with the requirement of A3.5, B06-class AAC products regulated by autoclaved aerated concrete building blocks (GB 11968-2006). The optimal grinding time of iron ore tailings was 25 min. The AAC samples after autoclaving were examined by using XRD (X-ray diffraction analysis), SEM (scanning electron microscope) as well as 29Si and 27Al NMR (Nuclear Magnetic Resonance). Results show that the main minerals in the AAC samples are tobermorite-11 Å, C-S-H gels, calcite, anhydrate, ferrotschermakite, quartz, with small amount of other minerals brought in by the iron ore tailings. It was also suggested that most minerals in the iron ore tailings participated in the hydration reaction, and the chemical elements in them got into the structure of acicular and platy tobermorite in the subsequent autoclaving process.
Cuvinte cheie
Steril de fier, beton cellular autoclavizat, tobermorit, mechanism de reacție
HUAWANG SHI, LIANYU WEI, YANCANG LI, RHUIZHEN GAO
Rezumat
In order to investigate the fatigue performance and microstructure evolution of glass fiber reinforced plastic mortar (FRPM) pipes under cyclic loading, fatigue test was carried out. In the process of fatigue test, the deflection, crack and crack width of each feature of FRPM were observed and recorded. Then, the micro-structure of original samples was scanned by electron microscope(SEM). Mechanical properties of FRPM pipe is analyzed from the view of microstructure for the specimens before and after fatigue loading. Finally, the fatigue life of FRPM pipe under cyclic loading is predicted. The results show that the residual stiffness of FRPM pipe decreases monotonically with the increase of fatigue times, therefore the stress amplitude or stress level is the main influencing factor. The FRPM pipe has a smaller residual stiffness and shorter fatigue life when being applied higher maximum cycling stress and amplitude. The crack in the FRPM tube without fatigue occurs instantaneously and obviously larger than that after fatigue.
Cuvinte cheie
Performanțe mecanice, FRPM, microstructură, proprietăți la oboseală, SEM
ANA J. MOMČILOVIĆ-PETRONIJEVIĆ, GORDANA A.TOPLIČIĆ-ĆURČIĆ,DRAGAN M. ĐORĐEVIĆ, DUŠAN Z. GRDIĆ, ZORAN J. GRDIĆ, NENAD S. RISTIĆ
Rezumat
Felix Romuliana is an archeological site located in the vicinity of Zaječar, in the east part of Serbia, south of the Danube. Felix Romuliana is a monument of Roman court architecture in the period of the Tetrachy. It is the only archeological site in Serbia, which is under the UNESCO’s protection. It is a fortified palace, built at a request of the Roman Emperor Gaius Valerius Maximianus, in the honor of his mother Romula, which is why it was named Romuliana. There are two fortification systems around this palace: and older inner system, and a younger outer system which encompasses the palace, temples, military facilities, storage buildings…Mortar samples were analyzed with the goal of obtaining information about their morphological, mineralogical, chemical and basic physical properties. For an analysis of these properties, optical and scanning electron microscopy were used, as well as XRF and XRD analysis. Depending on the location of the sampled mortars, differences of the individual properties of mortar were observed. The mortar analysis determined that lime was used as a binder. The mortars prevalently consist of the river aggregate grains, crushed limestone aggregate grains and traces of crushed masonry blocks. Further research should be focused on production of repair mortars.
Cuvinte cheie
Romuliana, mortare, XRF, XRD, SEM/EDS, stereo microscopie
CRISTINA DIMA (VĂDUVA), ALINA BĂDĂNOIU, ȘTEFANIA STOLERIU, DIANA LUCA
Rezumat
Studiul prezintă o posibilitate de valorificare a cenușii rezultate prin arderea unor reziduuri cu conținut de hidrocarburi din industria petrolieră (deșeul A). Înlocuirea ipsosului cu 5%, 20% și 30% (procente gravimetrice) de deșeu A, are ca rezultat modificarea rezistenței la compresiune în corelație cu cantitatea de ipsos substituită; creșterea proporției de cenușă A (de la 5% la 30%) determină o întârziere a prizei astfel încât la un dozaj de 30% cenușă, timpul de priză este similar cu cel impus de normative pentru lianții de ipsos. Activarea cenușii A cu adaosuri de săruri (sulfați) scurtează timpul de priză și mărește rezistența la compresiune a pastelor liante.
Cuvinte cheie
Valorificare, deșeuri de cenușă, gips
CARMEN OPROIU, MARIUS PÂRVAN, GEORGETA VOICU, ALINA IOANA BĂDĂNOIU
Rezumat
O metodă comună utilizată pentru inertizarea deșeurilor industriale este solidificarea/stabilizarea (S / S); se impune amestecarea deșeurilor cu un liant anorganic astfel încât produsul final să respecte standardele impuse de agențiile de mediu. Solidificarea descrie procesele care transformă deșeurile într-un solid rezistent la apă, cu coeziune puternică, adică proprietăți fizice și mecanice bune. Stabilizarea este efectul proceselor care vizează reducerea sau chiar eliminarea fenomenului de transfer de masă al poluanților în apă și sol. Această lucrare prezintă inertizarea și imobilizarea unui deșeu bogat în crom (din industria dicromatului de potasiu) în matrice anorganice bazate pe lianți hidraulici, și anume în structuri speciale numite ciment C și ciment D. De asemenea, sunt prezentate rezultatele privind influența deșeului asupra hidratării -hidroliză și asupra proprietăților principale ale mortarelor, rezultate obținute prin difracția razelor X, analiza termică complexă, microscopia electronică de scanare (SEM și EDX).
Cuvinte cheie
Lianți hidraulici speciali, proprietăți, deșeu, procese de solidificare/stabilizare
MIHAI BRATU, OVIDIU DUMITRESCU, OVIDIU VASILE, LUOANA FLORENTINA PASCU, CAROL LEHR
Rezumat
Poluarea, sub toate aspectele ei actuale, reprezintă o preocupare permanentă şi actuală a cercetătorilor. De aceea, realizarea de materiale fono-absorbante care să înglobeze deşeuri este o abordare foarte utilă.
Lucrarea atinge două aspecte legate de mediu şi anume: poluarea fonică datorată diferitelor surse din industrie şi transporturi, dar şi depozitarea deşeurilor care afectează calitatea mediului înconjurător.
Lucrarea prezintă cercetări privind obţinerea unor materiale oxidice ce conţin diverse deşeuri solide. Este descris schematic procedeul de obţinere, precum şi compoziţiile efective ale acestor materiale.
Au fost măsurate o serie de proprietăţi fizico-mecanice pentru caracterizarea acestor materiale: distribuţia granulometrică a materialelor de start, rezistenţă mecanică la compresiune, densitatea aparentă şi porozitatea aparentă, precum şi capacitatea de absorbţie a undelor sonore.
Cuvinte cheie
Deșeuri solide, proprietăți fizico mecanice și microstructurale, coeficient de absorbție fonică
Evaluation of strength and durability of natural fibre reinforced high strength concrete with M-sand
SHANMUGA PRIYA T, THIRUMALINI S
Rezumat
The experimental investigation was carried out to study the variation in strength and durability properties of high strength concrete incorporated with sisal, banana and coir fibres. In this study, three different percentage 0.5%, 1% and 1.5% by volume of sisal , banana and coir fibres were casted and results compared with control mix. The strength properties such as compressive strength, splitting tensile strength and flexural strength and durability properties like water absorption, sorptivity and rapid chloride permeability was studied. Test results show that, the addition of sisal , banana fibre and coir fibre resulted in the enhancement of compressive strength, splitting tensile strength and flexural strength of concrete in the range of 4% to 10%. The optimum mix was arrived as 1% sisal and banana fibre and 0.5% coir fibre. The durability properties of optimum mix like water absorption, sorptivity and Rapid Chloride Penetration Test (RCPT) values have better performance compared to control mix due to its pore filling effect of natural fibres making the concrete denser.
Cuvinte cheie
Fibre naturale, rezistență, durabilitate, beton de înaltă performanță
HAIYAN LI, QI QIAO, BOYANG ZHANG
Rezumat
Reactive powder concrete (RPC) is characterized by the ultra-high strength and excellent durability, so it has widely application prospects in the fields of oil, nuclear power, municipal works, marine engineering and military facilities. This paper will focus on the flexural properties of RPC after high temperature. To do this, 300 specimens with the size of 40×40×160mm were tested after exposure to 20~900℃. The effect of the fiber type and dosage change on the spalling of RPC is investigated through high-temperature test. By bending experiments, the degradation of RPC flexural strength with heating temperature, fiber type and fiber content are studied. The results indicate that, with the increase of steel fiber and polypropylene fiber dosage, RPC spalling probability reduces significantly. The flexural strength decreases with increasing temperature, and the incorporation of steel fibers exhibits positive impact on flexural strength, but the polypropylene fibers exhibit adverse effect. Formulas are proposed to express the decay of the flexural strength with increasing temperature, and the results are compared with normal strength concrete (NSC) and high strength concrete (HSC).
Cuvinte cheie
Beton cu pudră reactiv, temperatură ridicată, rezistență la flexibilitate, fibre de oțel, fibre de polipropilenă
ZHIHAI HE, JINGYU CHANG, CHUANG LIU, SHIGUI DU, MAN HUANG, DENG CHEN
Rezumat
The effect of rice husk ash (RHA) without processing content on compressive strengths of concrete with different strength grades was studied experimentally at 28 days. The size effect of specimen on compressive strengths was also analyzed and discussed. The results indicate that RHA without processing reduces the cubic compressive strengths of concrete, the brittleness coefficient and the size effect of strengths. With the increase of RHA content, the reduction effect is more and more obvious. There exists a good linear relationship between the brittleness coefficient and the size effect of strengths of concrete. Based on the brittleness coefficients, the size effect law is proposed, which can well predict the size effect of cubic compressive strengths of concrete. RHA without processing increases the volume fractions of porosity and high-density calcium silicate hydrates, but reduces the volume fractions of calcium hydroxide.
Cuvinte cheie
Beton, cenușă de coji de orez fără procesare, rezistență la compresiune, fragilitate
MERT TERZI
Rezumat
Sensitive determination of the particle size distribution is an important procedure in terms of efficiency as well as affordability in mining operations which includes many stages such as blasting and mineral processing. Digital image processing methods used in mineral processing discipline found different application areas due to providing accurate data in relatively short time. In this study, the particle size distribution analysis of the samples taken from privately owned aggregate processing plants using sieve analysis and digital image processing methods were conducted and accordingly a comparison of these methods in terms of the applicability on industrial scale were realized. In this context, a pilot setup was assembled for the laboratory and plant scale image processing analysis purposes. Particle size distribution measurements of the samples were conducted by digital image processing method using this pilot setup and conventional sieve analysis methods. As a result, d20, d50 and d80 sizes of a crushed stone plant product were determined with confidence levels of 94.75%, 88.45% and 80.00%, respectively. The obtained results showed that a system based on digital image processing method can be applied in particle size analysis with high success as alternatives to conventional methods.
Cuvinte cheie
Agregate, distribuție granulometrică, procesare digitală imagine
D. ELAVARASI, K.SARAVANA RAJA MOHAN
Rezumat
Several research works have been executed to examine the performance of slurry infiltrated fibrous concrete (SIFCON) under static and impact loading. But limited works have been done on the strength and durability characteristics of SIFCON made with binary blends of supplementary cementitious materials. The experimental investigation was carried out to study the strength and durability characteristics of slurry infiltrated fibrous concrete with partial substitution by fly ash (10, 15, 20, 25 & 30% as replacement of cement. SIFCON matrix containing a constant fibres content (10%) and water/binder = 0.4 were used throughout the entire investigations. The test results revealed that the incorporation of a blended cement with fly ash in SIFCON decreases the mechanical properties and improves the durability thus indicates the sorption coefficient decreases compared to control specimen. Regression model has been developed from the experimental results for estimating the compressive strength, split tensile strength, flexural strength and water permeability of SIFCON made with the binary cementitious blend of fly ash. The predicted values were satisfied with the experimental results.
Cuvinte cheie
Cenușă de termocentrală, SIFCON, Factor de ductilitate, rigiditate, permeabilitate, coefficient de sorbție, rezistență la acid