Spectrum analysis of the interfacial zone of lightweight aggregate concrete

Fourier Transform Infrared spectrum analysis was employed to study the phase transformation characteristics of the Interfacial Zone. In this research, three groups of infrared spectra with regular patterns were determined. These corresponded with three parts of the concrete, i.e. the aggregate core, the aggregate shell and the hardened cement paste. The transition between two zones corresponded to a remarkable change in the characteristic peak, either with the absence of a peak or a shift in the peak. The outcome of the spectrum analysis employed in this research shows that the cement paste diffuses into the aggregate shell through the interface between lightweight aggregate and cement paste. The water absorption by the dense hardened cement paste is also greater than the materials in the interface and inside the lightweight aggregate. The use of Fourier Transform Infrared spectrum analysis could become a good means for measuring the cement paste diffusion across the interface. © 2004 Elsevier B.V. All rights reserved.