Experimental study on the interfacial behavior of normal and lightweight concrete

• Autores: Shih Wei Cho
• Localización: Revista de la Construcción, ISSN-e 0718-915X, ISSN 0717-7925, Vol. 18, Nº. 3, 2019, págs. 476-487
• Idioma: inglés
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• Resumen

  • The interface between aggregate and mortar or paste is a weak phase. This has a serious effect on the properties of concretes. Because of the high porosity of lightweight aggregate, the interface of lightweight concrete is different from that of normal weight concrete. In this study, the effect of interfacial interactions between lightweight aggregate and mortar on the mechanical and chloride ion transport properties of concretes was investigated. The test variables were the volume fraction of the lightweight aggregate and the water–cement (W/C) ratio. The elastic modulus, the electrical charge passed from the rapidchloridepenetration test (RCPT), and chloride ion penetration depth were determined. In addition, scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) were used to observe the microstructures of the interfaces. SEM observation of the lightweight concrete revealed that the interface bonding between mortar and aggregateis considerably firmer than that of normal weight concrete. However, test results indicate that the ability of the lightweight concrete to resist chloride ion intrusion is worse than that of normal weight concrete. Comparison with theoretical models reveals that a negative factor affects the chloride ion transmission in lightweight concrete. As the volume fraction of lightweight aggregateincreased, this negative influence is also increased. Chloride ions were detected both in the mortar and the lightweight aggregatein the EDX test. This indicates that chloride ions passed through the lightweight aggregateduring the RCPT and can thus influence chloride ion transmission throughout lightweight concrete.