Study of the bamboo leaf ash potential for its use as a pozzolanic and sustainable material in cementitious matrices

Author(s)

Maria Júlia Bassan de Moraes

• Document type: Master's Dissertation
• Press: Ilha Solteira. 2019-03-08.
• Institution: Universidade Estadual Paulista (Unesp). Faculdade de Engenharia. Ilha Solteira
• Defense date: 2019-02-18
• Advisor: Jorge Luís Akasaki

Abstract

The global context of concern for the environment, its unrestrained use and emission of greenhouse gases, especially the emission of carbon dioxide, highlighted the importance of research to find new sustainable alternatives in the means of production, among them, the Portland cement industry. The proposal of this study is a new sustainable alternative for civil construction, studying bamboo leaf ash (BLA) as pozzolanic material to be used as partial replacement of Portland cement. The bamboo leaf ash was produced by a process of autocombustion without temperature control, and was characterized physically and chemically by means of X - Ray Fluorescence (FRX), determination of the amorphous silica content, X - Ray Diffractometry (XRD), Laser Granulometry, Field Emission Scanning Electron Microscopy (FESEM), Fourier Transform Infrared Spectroscopy (FTIR) and Thermogravimetric Analysis (TGA). The reactivity analysis was carried out by means of electrical conductivity and pH measurements, Frattini analysis and calcium hydroxide / CFB and Cement / CFB pastes, which were assessed by FTIR, TGA and FESEM analysis. In order to evaluate its influence on the mortar in the fresh and hardened states, the tests of consistency index and compressive strength were carried out, comparing mortars with cement partial replacement with a control mortar, without mineral addition. The influence of the ash on durability was analyzed by means of mercury intrusion porosimetry analysis (MIP) and acid neutralization capacity. The results obtained showed that the studied CFB is mainly composed of silica (74,23%), 92,33% of which are amorphous silica. The optimal milling time of the ash is 50 minutes. The fluidity of the cementitious matrix is impaired with the addition of ash but remains acceptable. The CFB was classified as highly reactive, which reflected in its influence on the mechanical behavior and durability of the cementitious matrices. All the mortars containing CFB presented very similar compressive strength to a control mortar after only 3 days of curing and at the following tested curing ages: 7, 28 and 90 days. In the mercury intrusion porosimetry analysis, the pastes with 20 and 30% CFB content presented higher tortuosity or fewer connected pores than the control paste. Thus, the auto-combustion method proved to be successful and CFB is a suitable and sustainable alternative for OPC partial replacement in cementitious matrices. (AU)

• FAPESP's process: 16/16403-5 - New high performance biocements: use of bamboo leaf ash
• Grantee: Maria Júlia Bassan de Moraes
• Support Opportunities: Scholarships in Brazil - Master