Long-term strength and durability parameters of lightweight concrete in hot regime: importance of initial curing

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.     

A new lightweight metal-composite-metal panel for applications in the automotive and other industries

A new lightweight metal-composite-metal (MCM) panel is developed. This panel consists of two layers of 0.2-mm thick stainless steel sheet with a layer of woven fabric (semi-flexible composite) in between. The stiffness and the dent resistance of this MCM-panel are compared to those of corresponding panels pressed in 1-mm thick aluminium, 0.8-mm thick carbon steel and 0.8-mm thick stainless steel sheets. Compared to the aluminium panel, the MCM-panel exhibits a slightly smaller stiffness. However, the MCM-panel displays a larger dent resistance than the aluminium and the carbon steel panels. The new panel is 46% heavier than the aluminium panel. However, it is 60% lighter than the carbon and stainless steel panels. This new panel is expected to have many applications in manufacturing of parts for car, train and bus bodies, appliances and household machines. Machine chassis and air cargo containers are other examples of products, in which the new panel can be used. Production of the new panel requires that the tools be heated. The cycle time is short, since a newly developed and patented method for ultra-rapid heating of tools has been used in this study. The production is economical, since the cycle times is short and recycled fibres can be used. The production process is not completely optimized yet. However, the conducted experiments show that the panel stiffness and dent resistance are benefited, if the tool pressure applied during the heating is low.     

轻烧白云石轻质墙体材料的研究

将白云石在合理的温度和时间下煅烧 ,以煅烧后的白云粉为主要原材料 ,配以调和剂以及各种外加剂、活性改性材料 ,在常温常压条件下自然养护 ,制成轻质内墙砌块、陶粒空心砌块及玉米秸轻质隔墙板。具有生产工艺简单、投资小、成本低廉、轻质高强等优点     

Influence of steel fibres on strength and ductility of normal and lightweight high strength concrete

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.     

现浇泡沫轻质土在挡墙台后的应用

本文通过某高速互通匝道路基挡土墙台后采用现浇泡沫轻质土填筑的工程实例,介绍了挡土墙抗滑移稳定性不足的情况下的病害处理,以及一种新型的轻质材料现浇轻质泡沫土的应用和施工。     

轻质莫来石浇注料及其在轧钢加热炉上的应用

介绍了轻质莫来石骨料及用该骨料配制的轻质莫来石浇注料的性能，并介绍了该浇注料在轧钢加热炉上的应用情况。