Doping technique in the interfacial transition zone between paste and lateritic aggregate for the production of structural concretes

Abstract

This paper discusses the use of doping technique in the interfacial transition zone (ITZ) between Portland cement paste and lateritic aggregates with the objective of promoting the implementation of structural concrete. Doping technique consists of establishing the initial impregnation of the aggregate with a high performance paste in order to improve its binding to the matrix. A Scanning Electron Microscope (SEM) equipped with an energy dispersive X-ray (EDX) analysis system is used to observe the results of the technique in the ITZ. The results are observed through an analysis of the cement hydration products formed in the ITZ. An ITZ with high concentration of large crystals of calcium hydroxide (CH) is observed in plain concrete, whereas in concrete prepared with doping technique the ITZ is rich in calcium silicate hydrate (CSH). This result confirms the possibility of using this material, which has no commercial value nowadays, as an alternative aggregate for elaborating structural concrete.

Robust microencapsulated phase change materials in concrete mixes for sustainable buildings

“…In Figure 11a, the microcapsules are seen as embedded in the rough cement matrix. The structure is a typical image of rough cement matrix [45], which is a result of the hardening process of in any cement. In Figure 11b, calcium hydroxide, also known by its mineral name, portlandite crystals, with a wide range of hexagonal shapes and sizes seen in hardened concrete [46], is surrounding the microcapsules.…”

Effects of Bar Reinforcement Arrangement on Deformations and Cracking of Concrete Elements

“…1.1a). Trigo & Liborio (2014) investigated techniques to improve bond between the hydrated cement paste and aggregates and demonstrated characteristics of micro-cracking ( Fig. 1.1b).…”

A Stochastic Multi-scale Approach for Numerical Modeling of Complex Materials—Application to Uniaxial Cyclic Response of Concrete

“…For designing concrete structures, an equivalent homogeneous concrete model is sought, which has to represent concrete mechanical behavior in different loading conditions while accounting for mechanisms at lower scales [37]. Heterogeneities can be observed in concrete at different scales: aggregates of different sizes are distributed in a cement paste; the so-called interfacial transition zone where the aggregates are bound to the cement paste plays a key role in the concrete mechanical properties [38]; cement paste is composed of water, voids and of the products of the complete or partial hydration of the clinker particles, which generates a microscopic structure composed of numerous intertwined phases. FIGURE 1.…”

“…From left to right: equivalent homogeneous concrete (macroscale), equivalent heterogeneous concrete (E-mesoscale, 5 cm × 5 cm-square), actual heterogeneous concrete (A-mesoscale, 5 cm × 5 cm-square), and zoom on the underlying microstructure in the cement paste (20 µm × 20 µm-square observed through Scanning Electron Microscope, courtesy A.P.M. Trigo [38]). …”