An extensive dataset on micromechanical behavior and microstructure of 1000 days old B/S-based alkali-activated material.

This dataset contains extensive results on micromechanical behavior and microstructure of alkali-activated materials (AAM) with biomass ash (B) and silica fume (S) precursors. The data were collected at the laboratories of the Federal Center for Technological Education of Minas Gerais (CEFET-MG) in Brazil. Scanning electron microscope (SEM), optical microscopy (OM), and nanoindentation with instrumented penetration (NI) were performed from AAM in the hardened state and advanced age (1000 days). Data include loading curves, hardness, module of elasticity, and microstructure. Data may be useful for researchers and engineers in designing new alternative binders with improved durability.

Experimental dataset on the residual performance of fiber-reinforced cementitious composite subjected to high temperature.

The present dataset refers to the research article entitled "A multiscale investigation on the performance improvement of fiber-reinforced cementitious composites after exposure to high temperatures" [1]. Supplementary data on raw materials characterization, temperature recording, mass loss, water absorption, compressive strength, flexural behavior, pull-out response, fiber-matrix interface, and surface, microstructure and hardness of fibers are presented here. The continuous matrix was produced from cementitious grout containing Portland cement, sand, silica fume, superplasticizer, and water. The heating was carried out in an electric oven up to 260 °C. The bending tests was performed for fiber-reinforced cementitious composite (FRCC) with steel fiber contents of 1%, 3%, and 5% by volume, and for non-fibrous matrix. The pull-out test was performed using single fiber embedded in the matrix. The water absorption and axial compression tests was performed for non-fibrous matrix. The fiber-matrix analysis was performed from polished sections of fibers embedded in cementitious matrix. The fiber analysis was performed from steel fibers. The data refer to the residual properties after heating and slow cooling or to the reference condition without heating. The data can help in understanding residual performance of FRCC after exposure to high temperatures and may be useful for developing resilient building materials.

Effect of Non-Calcined Sugarcane Bagasse Ash as an Alternative Precursor on the Properties of Alkali-Activated Pastes.

BFS-MK-based alkali-activated materials are well established as an alternative for sustainable and green construction. This work aims to collaborate and encourage the use of biomass ashes, such as sugarcane bagasse ash (SCBA), as a precursor in alkali-activated materials (AAM). This ash is a rich source of aluminosilicate, which is a primary requirement for this application. In addition, this waste is still an environmental liability, especially in developing countries, and with a large volume of annual production. Thus, in this research, alkali-activated pastes (AA) were produced using sugarcane bagasse ash (SCBA), granulated blast furnace slag (BFS) and metakaolin (MK) as precursors. In addition, environmental gains were encouraged with energy savings, with no extra reburn or calcination steps in the SCBA. Thus, the precursors were characterized by laser granulometry, X-ray fluorescence spectrometry (XRF), X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The pastes were produced by mixing the precursors with the activator, composed of a mixture of sodium hydroxide 8 mol/L and sodium silicate. Aiming to study the incorporation of SCBA, all samples have a precursor/activator ratio and a BFS/(BFS + MK) ratio constant of 0.6. The compressive strength analysis, FTIR, XRD, TGA, SEM and isothermal calorimetry analyses pointed out the occurrence of alkaline activation in all proposed samples for curing times of 7, 28 and 91 days. The sample GM0.6-BA0 (15% SCBA) achieved the highest compressive strength among the samples proposed (117.7 MPa, at 91 days), along with a good development of strength throughout the curing days. Thus, this work presents the properties of alkaline-activated pastes using SCBA as a sustainable and alternative precursor, seeking to encourage the use of raw materials and alternative waste in civil construction.

Influence of Cooling Methods on the Residual Mechanical Behavior of Fire-Exposed Concrete: An Experimental Study.

This work reports the main conclusions of a study on the mechanical behavior of concrete under ISO 834 fire with different cooling methods. The aim of this research was to provide reliable data for the analysis of structures damaged by fire. The experimental program used cylindrical concrete test specimens subjected to ISO 834 heating in a furnace up to maximum gas temperatures of 400, 500, 600, 700, and 800 °C. The compressive strength was measured in three situations: (a) at the different temperature levels reached in the furnace; (b) after a natural cooling process; and (c) after aspersion with water at ambient temperature. The results indicate that the concrete residual compressive strength is fairly dependent on the maximum temperature reached in the furnace and revealed that concrete of a lower strength preserved relatively higher levels of strength. The cooling method significantly influenced the strength, albeit at a lower intensity. In all cases, the residual strength remained in the range of 38% to 67% of the strength at ambient temperature. The statistical analysis showed that the data obtained by the experimental program are significant and confirmed the influence of the conditions imposed on the residual strength.

Thin Slabs Made of High-Performance Steel Fibre-Reinforced Cementitious Composite: Mechanical Behaviour, Statistical Analysis and Microstructural Investigation.

The present study evaluated the mechanical behaviour of thin high-performance cementitious composite slabs reinforced with short steel fibres. For this purpose, slabs with 1%, 3% and 5% vol. of steel fibres were moulded using the slurry infiltration method. Fibres concentrated in the region subjected to traction during bending stresses. After curing for 28 days, all slabs underwent flexural testing. The slabs with 5% fibre showed significantly higher flexural strength, deflection and toughness compared to those of the control group without reinforcement. The dense fibre distribution, resulting from the production process, led to profiles with multiple random cracks in the region of failure of the slabs as the fibre content increased. The results of the statistical analysis showed the intensity of the correlation between the variables and revealed that the increase of the fibre content significantly influenced the parameters of mechanical behaviour (load, flexural strength, deflection, toughness and toughness factor). Images obtained by optical microscopy aided in understanding the fibre-matrix interface, showing the bonding surface between the constituents of the composite.