Influence of Wood Fly Ash on Concrete Properties through Filling Effect Mechanism

Abstract

This paper presents the results of an experimental study aimed at determining the influence of wood fly ash (WFA) from three Croatian power plants on the properties of concrete. First, the chemical and physical properties of WFA’s were determined. It was found that these properties are highly influenced by combustion technology, the type and parts of wood used as fuel, and the local operating conditions. Subsequently, workability, heat of hydration, stiffness development, 28-day compressive strength, apparent porosity, and capillary absorption were determined on concrete mixes prepared with WFA as cement replacement from 5–45% by weight. Cement replacement up to 15% with the finest WFA accelerated hydration, stiffness development, and increased compressive strength of concrete up to 18%, while replacement with coarser WFA’s led to a decrease in compressive strength of up to 5% and had more gradual heat liberation. The dominant effect that could explain these findings is attributed to the filler and filling effect mechanisms. At the same time replacement content of up to 45% had very little effect on capillary absorption and could give concrete with sufficiently high compressive strength to be suitable for construction purposes.

The Present State of the Use of Waste Wood Ash as an Eco-Efficient Construction Material: A Review

“… Pores in the reference concrete and reference sample with different proportions of WWA and SF (used from an open source journal of MDPI [ 91 ]). …”

Characterization of Concrete Exposed to Marine Environment

“…Selected mineral admixtures have a justified application in concrete, especially those exposed to aggressive marine environment, as they improve its properties or give it special properties by various mechanisms of interaction between solid particles [3]. The use of selected mineral admixtures improves the workability of concrete by reducing the size and number of gaps between relatively large grains of cement, and releasing trapped water, which contributes to better fluidity [4]. Mineral admixtures reduce the permeability of concrete by improving the pore structure and increasing the pore density.…”

“…In addition, mineral admixtures contribute to increasing the compressive strength of concrete and its durability [3,5,6,7,8,9]. The potentially negative contribution of mineral admixtures is reflected in the possibility of reducing the workability of concrete, which is often attributed to the increase in solid surface area due to the presence of fine particles that tend to adsorb water, replacement with filler containing large particles (> 45 µm) and open porosity of the particles which increases the specific surfaces [3,4]. Also, mineral admixtures can have negative effects on concrete properties in the form of reduced early compressive strength which can lead to higher permeability and lowering the pH value of concrete in favor of corrosion, so it is necessary to pay attention to composition, selection and dosage of mineral admixtures [3,10,11].…”

Biomass Bottom Ash as Supplementary Cementitious Material: The Effect of Mechanochemical Pre-Treatment and Mineral Carbonation

“…To date, biomass ash is mostly disposed of via landfills, imposing risks on both the environment and human health [ 15 , 17 ]. To mitigate this risk, the immobilization of biomass ash in cementitious materials, valorised as SCM, is a promising solution and has been investigated in various studies [ 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 ]. The behaviour of biomass ash as SCMs depends significantly on their physicochemical properties, which are affected by the combustion process (type of feedstock biomass, temperatures used during combustion, method of collection and storage) [ 17 , 36 , 37 ].…”

“…Pre-treatment of the biomass ash—including water washing [ 24 , 34 ], mechanical and chemical activation [ 23 , 38 ], heating, and removal of organic matter [ 29 ]—has been proven effective for improving the reactivity of the ash and thus the mechanical performance of biomass-ash-modified cementitious composites. It should be noted that the majority of the abovementioned studies concerned the utilization of BFA [ 18 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 31 , 33 , 34 , 35 ] in cement composites, and only a few focused on BBA [ 18 , 20 , 29 , 30 , 39 ].…”