In this study, the potential use of waste diatomaceous earth from the production of diatomaceous earth for filtration purposes, as an alternative raw material for foam glass production, was explored. The chemical and mineralogical composition and the high temperature behavior of waste diatomite were studied to assess its suitability for foam glass production. Glass-ceramic foams were prepared using NaOH solution as a foaming agent, via a hydrate mechanism. The influence of different pretreatments and firing temperatures on the foam’s structure, bulk density and compressive strength was investigated. High temperature behavior was studied using TG/DTA analysis and high temperature microscopy. Phase composition was studied using X-ray diffraction analysis. Glass-ceramic foam samples of a high porosity comparable to conventional foam glass products were fabricated. The pretreatment temperature, foaming temperature and sintering holding time were found to have a significant influence on foam properties. With increased pretreatment temperature, pyrogenic carbon from the thermal decomposition of organic matter contained in the raw material acted as an additional foaming agent and remained partially unoxidized in prepared foams. The bulk densities of prepared samples ranged from 150 kg/m3 to 510 kg/m3 and their compressive strengths were between 140 and 1270 kPa.

The focus of this research paper is the preparation of inorganic foam glass-ceramic with the utilization of waste diatomite as a raw material. The waste diatomite was first comprehensively characterized by the analysis of the chemical and mineralogical composition, particle size, thermal analyses, and microstructure by scanning electron microscopy. Followed by the pretreatment of the mixtures with the addition of a foaming agent which was sodium hydroxide. The mixtures were then formed by pressing them into pellets and fired by a powder sintering method. The pretreatment drying temperatures and firing temperatures of the prepared mixtures were evaluated. After firing, the resulting properties of the foam glass-ceramic were investigated with the utilization of an X-ray diffraction analysis, bulk density, and compressive strength. The possibility of utilization of waste diatomite in raw material mixtures for the preparation of inorganic foam glass-ceramic was investigated.

This paper deals with the use of calcinated clay and micronized limestone as supplementary cementitious materials (SMCs) for preparation of blended Portland cement CEM II/B-M (Q-LL). Clay used in this study was calcinated at 700°C and pozzolanic activity after calcination was assessed using accelerated R3 pozzolanic test and modified Chapelle test. The influence of calcinated clay and limestone addition on mechanical properties and hydration process was investigated and an optimal ratio for 35% clinker replacement was found. Initial decrease of mechanical strength at early ages, caused by SCM addition, was almost compensated during maturation of the binder.

Protection of concrete against aggressive influences from the surrounding environment becomes an important step to increase its durability. Today, alkali silicate solutions are advantageously used as pore-blocking treatments that increase the hardness and impermeability of the concrete’s surface layer. Among these chemical substances, known as concrete densifiers, lithium silicate solutions are growing in popularity. In the present study, the chemical composition of the lithium silicate densifiers is put into context with the properties of the newly created insoluble inorganic gel responsible for the micro-filling effect. Fourier-transform infrared spectroscopy was used as a key method to describe the structure of the formed gel. In this context, the gelation process was studied through the evolution of viscoelastic properties over time using oscillatory measurements. It was found that the gelation process is fundamentally controlled by the molar ratio of SiO2 and Li2O in the densifier. The low SiO2 to Li2O ratio promotes the gelling process, resulting in a rapidly formed gel structure that affects macro characteristics, such as water permeability, directly related to the durability of treated concretes.

This paper explores the possibilities of utilization of waste diatomite in foam glass production. Chemical and mineralogical composition, granulometry and high temperature behaviour of waste diatomite were characterized. Different possibilities of waste diatomite utilization in foam glass production were explored mainly via means of thermal analysis and hot stage microscopy. The effects of diatomite addition to waste glass were evaluated. Possibility of using NaOH as a foaming agent for foam glass production from waste diatomite and the effects of NaOH amount and reaction time on waste diatomite were investigated. Partial conversion of diatomite and clay to hydrates due to the reaction with NaOH lead to the decrease of the melting temperature and foaming of the melt was observed via hot stage microscopy. 30 wt. % NaOH addition allowed foaming of waste diatomite in the temperature ranges typical for foam glass production. Increased reaction time led to the intensification of the foaming process.