The paper presents results on strength development and durability of 35 and 50 MPa total lightweight concretes exposed to hot marine exposure conditions for a period of 7 years. An initial water curing of 7 days and subsequent seaside exposure was found more beneficial for the strength development of lightweight concrete. One day of initial curing and subsequent seaside exposure was not very conducive for the strength development. A marginal degradation in both the stiffness and the modulus of rupture of the concretes over the exposure period was observed. Likewise, the water penetrability of the two mixtures, for all the three initial curing regimes, increased over a period of 7 years. This establishes that the compressive strength of concrete is not synonymous with its durability. Overall, 3–7 days of initial water curing seems most desirable to enhance the durability of concrete exposed to hot salty marine exposure conditions. 相似文献
This paper presents the results of a series of experiments conducted to investigate the effectiveness of fibre inclusion in the improvement of mechanical performance of concrete with regard to concrete type and specimen size. Lightweight aggregate concrete and limestone aggregate concrete with and without steel fibres were used in the study. The compressive strength of the concrete mixes varied between 90 and 115 MPa and the fibre content was 1% by volume. Splitting tests on prisms and three-point bending test on notched beams were carried out on specimens of varying sizes to examine the size effect on splitting strength, flexural strength and toughness.
The experimental findings indicate that the low volume of fibre has little effect on compressive strength but improve remarkably splitting tensile strength, flexural strength and toughness. The increase in splitting tensile strength, flexural strength and toughness index for lightweight concrete seems much higher than that of normal aggregate concrete.
The size effect on prism splitting tensile strength is not significant beyond a critical (transition) size. There are apparent size effects on flexural strength and toughness index. As the specimen size increases, splitting and flexural strengths appear to decrease, and fracture behaviour tends to be more brittle. 相似文献
In this paper, the analysis of transient two-dimensional (2D) heat transfer in low sloped roof with forced ventilated cavity made from lightweight building elements (LBE) is presented. For the heat transfer analysis the 2D numerical model, which was verified with experiments, was used. Forced ventilated cavity was configured in two different ways. In the first case the cavity was configured with coloured thin metal sheet and in the second case with thin metal sheet with added layer of thermal insulation and radiation barrier. Beside the influence of the ventilated cavity configuration on the transient 2D heat transfer in the LBE and on the cavity outlet air temperature also the influence of the LBE thickness, specific air flow rate through the cavity, inner air temperature and wind velocity was analysed. Multi-parametric equations for determination of Fourier series coefficients were formed. These coefficients were used for evaluation of transient 2D heat transfer on the inner side of the roof and cavity outlet air temperature for a clear day. 相似文献
The first part of this experimental program was to determine the structural bond properties of lightweight concrete incorporating solid waste oil palm shell (OPS) as coarse aggregate and also to compare its behaviour with other types of lightweight aggregate concretes. Other properties of OPS concrete namely the split tensile strength, modulus of rupture and modulus of elasticity were also determined. The structural bond properties were determined through pull-out test. The results showed that the experimental bond strength of OPS concrete was much higher than the design bond strength as stipulated by BS 8110. In general, the properties of OPS concrete compared well with that of other structural lightweight concretes and the results obtained encourage the use of OPS as aggregates for the production of structural lightweight concrete. The second part of the experimental program investigates the durability performance of OPS concrete through water permeability and water absorption tests. 相似文献
Carbon steel fibre reinforced lightweight aggregates (LWA) were produced in a pilot scale rotary kiln. Narrow size fractions as well as not-sieved (as received) material were investigated according to European standards with a main focus on strength and density and compared to a reference material without fibres. Depending on the size of the pellets a fraction of the fibres oxidized during firing. A strength increase proportional to the amount of non-oxidized fibres within the pellet was observed. The crushing resistance for as received fibre reinforced pellets (bulk density 452 kg/m3) was 3.0 MPa corresponding to an increase in strength of 140%. The enhanced strength was also confirmed by the single pellet compression test. 相似文献