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A. Alsabry, V.I. Nikitsin, V.A. Kofanov and B. Backiel-Brzozowska

Abstract

The non-stationary moisture level of a cellular concrete wall board in a heated utility building located in the northern part of the town of Brest (Belarus), depending on the climatic influence, was assessed in this work. The results were obtained both in a calculation experiment and a physical test. It was observed that the main reason for the high moisture levels in cellular concrete is wind-driven rain intensifying the process of free capillary moisture transfer. A comparative analysis of the results of the physical test and the calculation experiment showed that the THSS software elaborated by the authors was able to predict the actual moisture levels of the shielding structure under study accurately enough when precise data concerning the thermal and physical characteristics of the materials as well as the occurring climatic influences were submitted.

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Elvija Namsone, Genādijs Šahmenko, Aleksandrs Korjakins and Eva Namsone

Abstract

Nowadays energy-efficient use of building resources is getting more and more popular. Technological developments have promoted production of new building materials with improved physical, mechanical and thermal properties. Foamed concrete with porous aggregate can serve as an alternative material for the existing lightweight concrete materials. This building material shows good mechanical and thermal properties, as well as capillary absorption and shrinkage test results that attest the longevity of this building material.

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Jurgita Malaiškienė, Evaldas Šemelis, Giedrius Girskas and Viktor Kizinievič

Abstract

The aim of this research is to determine the dependences of the physical mechanical properties of vibropressed concrete (pavement blocks) on the type of coarse aggregate used in the main layer. Sustainability of concrete pavement blocks is a really important matter. Five different batches of pavement blocks were produced, changing the consistence ratio of coarse aggregate in the main layer. There are two types of course aggregate: crushed gravel and granite. The consistence of a facing layer was not changed. All tests: density, tensile split strength, water absorption for vibro-pressed concrete units were made according to EN 1338:2003+AC2006.

Open access

Janis Justs, Diana Bajare, Aleksandrs Korjakins, Gundars Mezinskis, Janis Locs and Girts Bumanis

Abstract

In this study, the effect of pressure application (0-50 MPa) to fresh concrete right after casting and during the first 24 hours of hardening has been examined. Supplementary cementitious materials in a form of silica fume, nanosilica and ground quartz sand were used. The aim of pressure application was to reduce porosity, thus improving concrete mechanical properties. Considerable reduction in porosity and a subsequent increase in compressive strength reaching the level of Ultra-High Performance Concrete (UHPC) were achieved. Mechanical and physical properties were tested and gas sorption porosimetry, mercury intrusion porosimetry (MIP), X-ray diffraction (XRD), as well as scanning electron microscopy (SEM) were used for material characterization.

Open access

Aleksandr Bakatovich and Sergey Romanovskiy

Abstract

The paper presents results of analysis of thermal insulation materials based on plant fibers. It is suggested to use secondary raw materials of flax processing plants – flax noils – as a fiberfill in production of insulating slabs.

The paper presents results of research on the microstructure of flax noils and flax fibers conducted using light microscopy and electron microscopy, respectively. A set of experiments aimed at determining physical and mechanical characteristics of thermal insulation materials has been conducted. Test results attest higher efficiency of the insulating slabs made from flax noils in comparison with flax fiber-based thermal insulation material. The main factors facilitating reduction of thermal conductivity coefficient of thermal insulation material made from flax noils have been determined.

Open access

R.S. Raju, B.M. Reddy, M.M. Rashidi and R.S.R. Gorla

Abstract

In this investigation, the numerical results of a mixed convective MHD chemically reacting flow past a vertical plate embedded in a porous medium are presented in the presence of cross diffusion effects and convective boundary condition. Instead of the commonly used conditions of constant surface temperature or constant heat flux, a convective boundary condition is employed which makes this study unique and the results more realistic and practically useful. The momentum, energy, and concentration equations derived as coupled second-order, ordinary differential equations are solved numerically using a highly accurate and thoroughly tested element free Galerkin method (EFGM). The effects of the Soret number, Dufour number, Grashof number for heat and mass transfer, the viscous dissipation parameter, Schmidt number, chemical reaction parameter, permeability parameter and Biot number on the dimensionless velocity, temperature and concentration profiles are presented graphically. In addition, numerical results for the local skin-friction coefficient, the local Nusselt number, and the local Sherwood number are discussed through tabular forms. The discussion focuses on the physical interpretation of the results as well as their comparison with the results of previous studies.

Open access

Olga Finoženok, Božena Vanagel, Ramunė Žurauskienė and Rimvydas Žurauskas

Standards Board, Vilnius, p.19. 2009. [18] LST EN 12390-4 Testing hardened concrete - Part 4: Compressive strength - Specification for testing machines , Lithuanian Standards Board, Vilnius, p.17. 2003. [19] O. Finoženok, R. Žurauskienė, R. Žurauskas , “ Analysis of the physical - mechanical structural concrete properties when concrete waste additives are used in the mixtures,” in: The 10th International Conference “Modern building materials, Structures and Techniques” , June 2010, Vilnius, Lithuania. Vilnius: VGTU, 2010, pp.64 - 70.

Open access

Džigita Nagrockienė, Aurelijus Daugėla, Laurynas Zarauskas and Gintautas Skripkiūnas

–685, 2011. http://dx.doi.org/10.1016/j.resconrec.2011.02.002 [9] C. B. Cheah, M. Ramli. “Properties of high calcium wood ash and densified silica fume blended cement” International Journal of the Physical Sciences , vol. 6(28), pp. 6596–6606, 2011. [10] J. Deltuva, 1998. Heterogeninių statybinių mišinių sandasra ir savybės. Kaunas: Technologija. 263 p. [11] A. Naujokaitis, 2007. Statybinės medžiagos. Betonai. Vilnius, Technika.p. 355. ISBN 978-9955-28-209-9. http://dx.doi.org/10.3846/966-S [12] EN 197-1:2001/A1:2004. Cement - Part 1

Open access

Victor Mironov, Ina Pundiene, Alexey Tatarinov and Janis Baroninsh

References [1] DIN 1045-3 Tragwerke aus Beton, Stahlbeton und Spannbeton. Teil 3: Bauausführung, Ausgabe 2001, pp. 7. [2] I. B. Topçu. “Properties of heavyweight concrete produced with barite.” Cement and Concrete Research, vol. 33 (8), pp. 815-822, 2003. http://dx.doi.org/10.1016/S0008-8846(02)01063-3 [3] C. Basyigit. “The physical and mechanical properties of heavyweight concretes used in radiations.” Journal of Applied Sciences, vol. 6, pp. 762, 2006. http://dx.doi.org/10.3923/jas.2006

Open access

Akogu Elijah Abalaka and Obumneme Godwin Ahmadu Bello University

ash,” Cement and Concrete Composites , vol.33(5), pp.529-534, 2011. [13]G. Giaccio, G. Rodríguez de Sensale, R. Zerbino, “Failure mechanism of normal and high-strength concrete with rice-husk ash,” Cement and concrete composites , vol.29 (7), pp.566-574, 2007. [14]F. Giannotti da Silva, J. B. L. Liborio, P. Helene. (2008.). Improvement of physical and chemical properties of concrete with Brazilian silica rice husk (SRH), Revista Ingeniería de Construcción. [Online]. 23(1), pp.18-25. Available: http://www.scielo.cl/pdf/ric/v23n1