Compatibility of Plants with a Mineral Binder

Hemp concretes are the most widely used biobased concretes in France. However, their growth is still limited by the lack of knowledge and high variability of the performances of biobased concretes, especially for their mechanical properties. These results are related to interactions between the mineral binder and plant compounds that modify the hydration of the cement. In this work, the interactions between cement and eight types of hemp shiv, and a flax shiv are studied by isothermal calorimetry. The setting delays observed in the presence of plants are interpreted by analyzing the molecules extracted from these plants in water. A link can be observed between the setting delay and the coloration of the extract solutions or their concentration in reducing sugars and in polyphenols. These results constitute a basis in the objective to define an indicator enabling to predict the compatibility between plants and mineral binders.

Study of the hardening kinetics of a mineral binder using electrical and optical methods

Hardening of mineral binders (cement, gypsum, lime, clay) is accompanied by the dissolution of minerals from the binder surface, their chemical interaction with water (the reaction of hydration and hydrolysis), and the formation of a solution saturated with respect to new hydrates. The reactions of minerals with water continue for some time even after saturation when water molecules are adsorbed by the solid phase of the binder. An «intermediate» colloidal system thus formed is characterized by the viscosity or plasticity depending on the water content in it. At the final stage, the processes of recrystallization and coalescence of the particles in a colloidal solution occur resulting in solidification and hardening of the solution and increased strength of the formed stone. We present the results of studying the hardening kinetics of the aqueous solution of a mineral binder using electrical and optical methods with high time resolution. Semi-aqueous gypsum was selected as a mineral binder. During hardening, the resistance and the capacitance of the samples were measured along with the visualization of the spatial structure of the solution. The mineral composition of water significantly affected the character of hardening. Noticeable fluctuations of the electrical parameters were detected in the experiments with mineral water. Optical measurements showed that solidifying solution is similar in structure to dendrites and fractal dimensionality of the structure almost remains the same during growth. It is also shown that at the initial stage the hardening proceeds by the logistics law. The results obtained can be used and recommended for practical application for determination of the kinetic parameters of hardening and in diagnostics of the structure of materials based on mineral binders.

Non-conventional mineral binder-bonded lignocellulosic composite materials: A review

The construction industry suffers from unsustainability and contributes more than any other industrial sector to carbon emissions that lead to global warming. Increasing economic and environmental concerns related to conventional energy- and CO2-intensive building materials have propelled the rapid and sustained expansion of research in the area of plant-based inorganic mineral binder-bonded materials for the construction industry. The resulting composites can be qualified as eco-responsible, sustainable, and efficient multifunctional building materials. So far, most of these research efforts have not received as much attention as materials based on ordinary Portland cement (OPC). To address this gap, this review focuses on mineral binder-based lignocellulosic composites made from non-conventional inorganic mineral binders/ cements with low embodied energy and low carbon footprint, namely hydrated lime-based binders, magnesium-based cement, alkali-activated cement, and geopolymers, as sustainable alternatives to OPC-bonded lignocellulosic composites (state-of-the-art). The emphasis here is on the application potentials, the influence of production parameters on the material properties/ performance, and recent advancement in this field. Finally, a prediction is provided of future trends for these non-conventional mineral binder-bonded lignocellulosic composites.

EFFICIENCY OF STABILIZERS OF VARIOUS COMPOSITION FOR STRENGTHENING THE SOIL WITH A MINERAL BINDER

the depletion of natural deposits of traditional inert mineral raw materials (sand, gravel) used to create effective layers of the foundations of roads leads to the development and application of new technologies and alternative materials. One way to solve this problem is to use local raw materials. For the construction of the lower layer of the road basement local soils are often used. However, their use is associated with the development of a set of measures to increase their efficiency, such as stabilization (by the use of chemical additives) and/or strengthening (by the introduction of various types of binders). In this regard, the paper analyzes the physicomechanical characteristics of reinforced clay soils obtained by introduction of various types of stabilizing additives in the presence of an inorganic mineral binder of hydration hardening type - cement - taking into account the recommendations for the used additives. The object of research was the most common representative of clay soils of the Belgorod region – heavy dusty clay loam. As a result of the studies, the authors established the reasonability of the use of the additives in the presence of cement, the most effective compositions of the reinforced soil were identified, contributing to the improvement of its controlled physical and mechanical characteristics. In addition, the need for additional studies to adjust the recommended composition of reinforced soil was established.

Lightweight Concrete Manufacturing Technology Based on Waste Energy Raw Materials Alkaline-Activated

This article focuses on the compression strength of lightweight concrete based on alkaline-activated waste materials. The problem is important not only because of the possibility of disposal of excessive amount of building or industrial waste, but also because of the decreasing amount of natural aggregate deposits. Apart from the problem of the decreasing amount of natural aggregate deposits, there is also a problem related to the emission of greenhouse gases from cement production processes. It is estimated that the synthesis of alkaline-activated composites is twice as energy-intensive as the production of Portland cement and generates 4-8 times less carbon dioxide. Alkaline-activated concrete production can therefore lead to a significant reduction in environmental impact. The paper presents a thesis that there is a possibility of a monolithic combination of an alkaline activated mineral binder with an artificial ash-porbit aggregate, which will contribute to the improvement of the compression strength of light concrete based on alkaline activated energy waste materials and elimination of Portland cements.

A Multifunctional Mineral Binder for Plywood Production: The Effect of Manufacturing Parameters on Bonding Quality

Geopolymers show great potential for use as binders in developing and manufacturing multifunctional wood products. The objective of this study was to improve the bonding quality of a geopolymer binder, with wood veneers, using different manufacturing parameters. To this end, we produced five layered plywood panels treated with various lay-up times (1, 5, 10, 15 min), panel compressibility values during hot pressing (5%, 10%, 15%, and 30% compression), veneer roughness values (low, medium, and high roughness), press temperatures (120, 140, and 160 °C), and veneer layouts via changing the middle layer position of plywood relative to the surface layers. The results show that the shear strength and thickness swelling were negatively influenced by increasing the lay-up time of resinated veneers and panel compressibility. Increasing the veneer roughness significantly increased the panels’ properties. Furthermore, the panels produced with a pressing temperature of 140 °C showed the best performances. The veneer layouts also significantly changed the physical and mechanical properties of the plywood panels. Generally speaking, the results obtained in this study show that improving the bonding quality of geopolymer binders with wood can be done through the manipulation of plywood manufacturing parameters.

Relationship between operational properties of peat heat-insulating materials and the content of mineral binders in them

This work presents the main results of calculation and experimental study on relation between the operational properties of peat heat-insulating materials (HIM) and the content of mineral binders in them aiming at reducing heat energy costs by energy-consuming objects. It was experimentally proved that introduction of cement increases thermal conductivity, and introduction of calcium oxide as a mineral binder, on the contrary, promotes the development of material porosity while maintaining strength characteristics and elasticity and helps to reduce the thermal conductivity and specific density. The established relationship between the content of calcium oxide and the thermal conductivity enables modelling of technology for HIM producing based on peat and inorganic binders.