The objective of the presented paper is to investigate the performance of concrete containing volcanic scoria as cement replacement after 7, 28, 90, and 180 days curing. Five performance indicators have been studied. Compressive strength, water permeability, porosity, chloride penetrability, and reinforcement corrosion resistance have all been evaluated. Concrete specimens were produced with replacement levels ranging from 10 to 35%. Test results revealed that curing time had a large influence on all the examined performance indicators of scoria-based concrete. Water permeability, porosity, and chloride penetrability of scoria-based concrete mixes were much lower than that of plain concrete. Concretes produced with scoria-based binders also decelerated rebar corrosion, particularly after longer curing times. Furthermore, an estimation equation has been developed by the authors to predict the studied performance indicators, focusing on the curing time and the replacement level of volcanic scoria. SEM/EDX analysis has been reported as well.
Compressive strength of concrete having recycled concrete aggregate is influenced by the properties and amount of those aggregate. The worse quality of RCA can be eliminated by specific mixing approach. Practical mixing and delivery of concrete could affect the properties of ready concrete due to prolonged time. In this paper, both the fly ash and fine fraction of recycled concrete were used to improve the quality of concrete due to coating of RCA, while the triple mixing technology was applied for this purpose. The compressive strength is evaluated from two aspects: the curing time (2, 28 and 90 days) and discharge time (0, 45 and 90 minutes after mixing) with attention being paid to the type of aggregate and the type of coating material. When using triple mixing technology, prolonged discharge time brings only small effect on the compressive strength (up to 12%) both in positive and negative way, depending on kind of coating material.
Kheira Boutouba, Ismail Benessalah, Ahmed Arab and Ahmed Djafar Henni
water content ( ω = 3, 7 and 10 %), cement content ( Cc = 2.5, 5, 7.5 and 10%) and curingtime (7, 14 and 28 days).
2 Experimental program
A series of direct shear tests were carried out on the sandy soil of the Chlef area, from the banks of the Chlef Valley. The soil was initially air dried and sieved through a 2 mm sieve, Fig. 3(a) . Chlef sand particles are with a reduced grain shape and quartz with some carbonates, and they are usually isometric particles. Figure 1 shows a microscopic view of an electronic scanning of the tested sand
Engineering, vol. 20(1), pp. 39–47, 1989 .
. K. HARICHANE, M. GHRICI, S. KENAI: “ Effect of curingtime on shear strength of cohesive soils stabilized with combination of lime and natural pozzolana ”, International Journal of Civil Engineering, vol. 9(2), pp. 90–96, 2011 .
. N.C. CONSOLI, G.V. ROTTA, P.D.M. PRIETTO: “ Influence of curing under stress on the triaxial response of cemented soil ”, Géotechnique, vol. 50(1), pp. 99–105, 2000 .
. F.H.M. PORTELINHA, D.C. LIMA, M.P.F. FONTES, C.A.B. CARVALHO: “ Modification of a lateritic soil with
Based on known correlations permeability was calculated for the mixtures containing various proportions of selected FBC fly ash, Speswhite kaolin and lime. The influence of initial water content of the mixtures was also considered. The study was limited to the first four weeks of curing time. Results of calculations were discussed on the background of previously obtained observations for mixtures of tested materials.
In this work, composites made from styrene-butadiene rubber and short fibers were prepared by mixing and
investigated. The influence on the vulcanization process and tensile strength properties has been studied and
compared with compounds filled with carbon black. The presence of fibers gave shorter curing time and led to a
slight increase in tensile strength but decreased the elongation at break of the compound.
Cold Bituminous Emulsion Mixtures (CBEMs) could offer significant advantages in contrast to traditional Hot Mix Asphalt (HMA). These advantages are redaction of energy consumption, reduction of emission of pollutants, and reduction of total costs. To date, researchers have attempted, intensively, to upgrade CBEMs’ engineering characteristics to gain their whole advantages. Adding active filler materials such as Ordinary Portland Cement (OPC) develop these characteristics. In this paper, selected waste or by-product materials are investigated as alternatives to OPC. Although OPC alone or with activator has proven successful in improving curing time and mechanical properties, the successful use of waste or by-product alternatives could represent a unique environmental and economic achievement. Thus, for the first time, waste or by-product materials (PFA, PSA, GGBFS, APC, and BFA) were investigated individually and not as Supplementary Cementitious Material (SCM) for improving the curing and strength of CBEM. However, some of these filler showed significant improvement in CBEMs characteristics.
Diana Stegărus, Ecaterina Lengyel, Daniela Sandru, Dan Mutu, Ramona Iancu and Ovidiu Tiţa
This study monitors the physico-chemical properties of wines from Dragasani under the influence of pectolytic enzymes in various temperature conditions. during maceration contact is made between the grape skins and selected the optimal time leads to wines with more pronounced floral character. The physico-chemical extraction maceration leads to a more pronounced specific compounds, the time of maceration is very important in this case. The curing time is of great importance in producing varieties Muscat Ottonel and Tămâioasă Românească primarily for successful extraction of aromatic components from grape. As noted in the literature flavored grapes contain large amounts of terpene compounds are in free form or bound. To optimize the technological process is able to extract these compounds and to achieve a harmonious and balanced wine. The variants considered in the study presents the results of physico-chemical and aromatic wines obtained from the Muscat Ottonel and Tămâioasă Românească, which took into consideration both during maceration and the use of selected yeasts and enzymes, which form the basis for the selection of the optimal procedure for obtaining aromatic white wines in Dragasani Vineyard.
. 43 (2003)187-221; DOI:10.1081/MC-120020160.
D. Poncelet, V. Babak, C. Dulieu and A. Picot, Physico-chemical approach to production of alginate beads by emulsification-internal ionotropic gelation, Colloids Surface 155 (1999) 171-176; DOI: 10.1016/S0927-7757(98)00709-2.
P. L. Yagnesh, S. Praveen and A. P. Pawar, The effect of drug concentration and curingtime on processing and properties of calcium alginate beads containing metronidazole by response surface methodology, AAPS PharmSciTech in press; DOI:10
Stefan Dačić, Aleksandar Mitić, Marija Nikolić, Milica Cenić, Nenad Stošić and Dragica Dačić-Simonović
Dijken JW. Effect of power density of curing unit, exposure duration and light guide distance of composite depth of cure. Clin Oral Investig 2005;9(2):71-6. http://dx.doi.org/10.1007/s00784-005-0312-9
4. Caughman WF, Caughman GB, Shiflett RA, Rueggeberg F, Schuster GS. Corelation of cytotoxicity, filler loading and curingtime of dental composites. Biomaterials1991;12 (8):737-40. http://dx.doi.org/10.1016/0142-9612(91)90022-3
5. Živković S. Osnovi restaurativne stomatologije. Datastatus. Beograd. 2009, pp229-50.
6. Davidson Cl, Feilzer AJ