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Abstract

Concrete block pavements have become an attractive engineering and economical alternative to both flexible and rigid pavements because of it’s high strength and durability. The influence of pozzolanic mineral additions – natural zeolite and expanded perlite powder on the properties of concrete interlocking blocks in different curing conditions has been studied. The use of zeolite as a substitute for cement in the production of concrete blocks increased the water demand but decreased the water absorption of the blocks. Obtained results show, that concrete blocks with 10% substitution of cement with zeolitic tuff is characterized by higher strength, lower mass loss and absence of efflorescence.

Concrete, Leipzig, June 2002, 1421-1436. 18. H. Zanni, M. Cheyrezy, V. Maret, S. Philippot, P. Nieto, Investigation of hydration and pozzolanic reaction in reactive powder concrete (RPC) using 29Si NMR, Cement and Concrete Research, 26, 93-100, 1996. 19. T. Zdeb, J. Sliwiński, Effect of curing conditions and steel fiber addition on the compressive and flexural strength of reactive powder concrete (in Polish), Inzynieria i Budownictwo, 12, 693-697, 2008. 20. T. Zdeb, The influence of composition and production technology on selected properties of reactive powder concretes

with intermittent hetaing and ventilating for burley tobacco in Japan; Presented at the 50th Tobacco Chemists’ Research Conference, Richmond, Virginia, USA, 1996, Abstract 37, p. 42. 10. Long, R.C., I. Wahlberg, P. Brandt, and A. Wiernik: The development of low TSNA air-cured tobaccos. II. Effects of curing conditions and post-curing drying on TSNA formation; Presented at the CORESTA Meet. Agro-Phyto Groups, Suzhou, China, 1999, Abstract 39, p. 13. 11. Saito, H., H. Komatsu, Y. Ishiwata, K. Koga, and S. Fujii: Heat treatment and TSNA formation in burley tobacco

Abstract

The present study aimed to analyze the interference of different curing conditions on the development of the concrete compressive strength under the perspective of construction management. It is known that the conditions of humidity and temperature are the main factors related to the behavior of the concrete strength, so that modifying these parameters directly affects the material’s behavior and, consequently, construction management. Forty-two specimens of concrete were molded and each 6 specimens were submitted to different temperature and humidity conditions. The first group was oven-cured at a temperature of 100°C. The second and third groups were kept at ambient temperature of 23 ± 2°C being that the latter was submerged in water and the former was exposed to the air humidity. The specimens of groups 4 and 5 were placed in a freezer at 5°C. Group 4 was submerged in water and group 5 was not. The curing of group 6 occurred under submerged condition with water at about 100°C. Group 7, on the other hand, was cured in water vapor. The group submitted to curing at room temperature and submerged condition was the one with the highest compressive strength value, while the ones with the lowest compressive strength were the groups of samples cured in the oven and those submerged at 100°C. The results were compared and tested using statistic methods, which proved that the curing conditions directly affected concrete properties.

Abstract

This paper focuses on the mechanical properties and modulus of elasticity of fly ash and GGBS based geopolymer concrete. In this study an 8 molarity concentration of NaOH and alkaline liquid ratio in a ratio of 2.5 was used. This study includes the stress-strain behaviour along with the flexural strength, compressive strength and split tensile strengths for the GPC20, GPC40 and GPC60 grades. Tests were carried out on 150 mm × 150 mm × 150 mm cubes and 100 × 100 × 500 mm prisms and 150 × 300 mm cylindrical geopolymer concrete specimens. The test results not- ed the good mechanical properties and measured stress-strain relations of fly ash and GGBS based geopolymer concrete under ambient curing conditions. The elastic modulus was significantly varied with increases in the grade of the concrete. An equation was proposed to determine the modulus of elasticity based on the compressive strength of the geopolymer concrete.

Abstract

Mortar is widely used in the construction industry for different purposes. Its compressive strength is the main parameter which is brought under focus. Compressive strength of mortars depends upon many factors such as water-cement ratio, fine aggregates size, and different curing conditions. This experimental study was undertaken to investigate the effect of GGBFS on compressive strength of mortars under different curing regimes using GGBFS as a partial replacement of cement. A total of 60 cubes of standard size of 2 x 2 x 2 inches were casted in laboratory, out of which 12 cubes each were prepared with 0%, 5%, 10%, 15% and 20% GGBFS replacement for cement. Cubes were cured for 3, 7, 14 and 28 days. Bases on obtained results it is observed that the maximum compressive strength was achieved by sample with 5% GGBFS, although 10% GGBFS samples achieved higher compressive strength than the control sample with 0% GGBFS. Further replacement beyond this value causes reduction in strength.

Abstract

Efforts over the past few years for improving the performance of concrete suggest that cement replacement with mineral admixtures can enhance the strength and durability of concrete. Feasibility of producing good quality concrete by using alccofine and fly ash replacements is investigated and also the potential benefits from their incorporation were looked into. In this study, an attempt has been made to assess the performance of concrete in severe marine conditions exposed upto a period of 150 days. This work investigates the influence of alccofine and fly ash as partial replacement of cement in various percentages (Alccofine - 5% replacement to cement content) and (fly ash - 0%, 15%, 30%, 50% & 60% to total cementitious content) on mechanical and durability properties (Permit ion permeability test and corrosion current density) of concrete. Usage of alccofine and high quantity of fly ash as additional cementitious materials in concrete has resulted in higher workability of concrete. Inclusion of alccofine shows an early strength gaining property whereas fly ash results in gaining strength at later stage. Concrete mixes containing 5% alccofine with 15% fly ash replacement reported greater compressive strength than the other concrete mixes cured in both curing conditions. Durability test conducted at 56 and 150 days indicated that concrete containing higher percentages of fly ash resulted in lower permeability as well lesser corrosion density.

Abstract

Sands reinforced by hydraulic binders (cement) have constituted in recent decades a major asset for the expansion of several areas of engineering. The mechanical behavior of sand-cement mixtures has undergone some controversies studied on the Chlef sand. In this paper, we present an experimental study to investigate the mechanical behavior of a sandy soil reinforced by a hydraulic binder (cement), using the direct shear apparatus emphasizing on the shear strength characteristics and the vertical deformation variation of cemented reinforced sand. The parameters used in this study are mainly: relative density (Dr = 80%), normal stress (σn = 100, 200, 400 kPa), water content (3, 7 and 10%), cement content (2.5, 5, 7.5 and 10 %) and cure time (7, 14 and 28 days). The experimental results show that the mechanical characteristics in terms of internal cohesion (C) and internal frication angle (φ) give a better mechanical performance with the binder inclusion, and the cure conditions play an effective role on the improvement of the shear strength. This result also showed that 10% of the cement content gave us a maximum value of shear strength and an optimal influence on the mechanical characteristics. The addition of cement not only improves the shear strength of soil, but also provides diversity in the resistance against the deformations imposed load, which can be established by a dilatant character.

. Zeng and et al “Deterioration of mortars exposed to sulfate attack under electrical field” Construction and Building Materials, Vol. 117, 2016, pp.121-128. 14. E. Sakai, S. Miyahara, S. Ohsawa and et al “Hydration of fly ash cement” Cement Concrete Research, Vol.35, 2005, pp.1135-1140. 15. P. Termkhajornkit, T. Nawa and K. Kurumisawa “Effect of water curing conditions on the hydration degree and compressive strengths of fly ash-cement paste” Cement and Concrete Composites, Vol.28, 2006, pp.781-789. 16. Q. Huang, C. Wang, C. Yang and et al “Accelerated sulfate attack

53, 2013, pp.258-266 5. BozkurtNusret&YaziciogluSalih,“ Strength and capillary water absorption of lightweight concreteunder different curing conditions” Indian J Eng Mater sci, Vol.17, 2010,pp.145-51. 6. Gomathi P &Sivakumar A,“Accelerated curing effects on the mechanical performance of cold bonded and sintered fly ash aggregate concrete” Construction and Building Materials, Vol.77, 2015, pp.276-287. 7. Al-Khaiyat H &Haque N, “ Strength and durability of lightweight concrete in hot marine exposure conditions” Master struct, Vol.32, 1999, pp.533.8 8. MehtapkPK