Use of Off-ASTM Class F Fly Ash and Waste Limestone Powder in Mortar Mixtures Containing Waste Glass Sand

Developing sustainable concrete with less ordinary Portland cement is a growing issue in the construction industry. Incorporating industrial by-products (such as fly ash or slag) or municipal solid wastes (such as waste glass or recycled concrete aggregate) into the concrete becomes an effective way to reduce the consumption of natural sources and carbon dioxide emission if a proper mix design is provided. The present study examines the influence of the combined use of off-ASTM Class F fly ash (FFA) and waste limestone powder (LSP) on flowability, compressive strength, and expansion characteristics of mortar mixtures containing waste glass sand (WGS). FFA and LSP were used as cement replacement while WGS was used as partial reactive siliceous river sand replacement. Material variables included different WGS replacement ratios (25%, 50%, and 75%) with river sand, LSP contents (25%, 50%, and 75%), FFA contents (15%, 30%, and 45%), and different combinations of FFA-LSP (15–10%, 15–15%, 15–30%, and 15–35%). It is shown that the single use of FFA or LSP reduces both compressive strength and flowability of mortar mixture as its replacement level increases. However, mixtures combined with FFA and LSP provide higher or comparable strength to the single LSP or FFA mixture. For the expansion characteristics due to alkali-silica reaction, the single-use of more than 30% FFA or 75% LSP has less than 0.1% expansion, which is a non-reactive aggregate criterion based on the C1260/C1567 when the test period is extended to 56 days. Moreover, the combination of FFA and LSP has a considerable reduction in expansion rate compared to the single FFA or LSP mixture.

Thermal insulation of autoclaved materials

The construction industry relies on the production of building materials, which are created as a result of particular actions of binding materials widely used in construction, and directly condition the quality of life of a society. Following these thesis, one should create possibilities of conscious choice and use of building materials not only among scientists and constructors, but among the whole society. Two types of additives are used in building materials: additives with a crystalline structure (SiO2) and additives with an amorphous structure (fly ash), which affects the properties and durability of materials. In the last decade industry is also moved on the fight against global warming and overproduction of materials. In May 2019, the level of CO2 concentration in the atmosphere exceeded 415ppm, which was the highest result in the last 50 years. Overproduction is, in turn, associated with the excessive use of natural resources (SiO2) and since 2010 there has been talk of the “sand deficit”. One way to combat overproduction is to use and promote recycling to avoid excess waste. The article describes the method of managing recycled glass sand in autoclaved materials and checking their thermal properties. This study describes the relationship between the physical (thermal isolation), mechanical and microstructural properties of autoclaved materials which undergone hydrothermal treatment and consist of lime (7%) and were modified through the introduction of glass components (up to 90%). For this modification, a certain amount of crystalline SiO2 was replaced with amorphous glass sand. Hydrated calcium silicates are formed in building materials (CaO-SiO2-H2O).

Study on the Effect and Mechanism of Alkali–Silica Reaction Expansion in Glass Concrete

The suppression of ASR expansion hazards of glass concrete has always been a key and hot issue in the research of glass concrete. According to the ASTM C1260-14 fast mortar rod method, glass sand and glass powder act as fine aggregate and auxiliary cementing material, respectively. The changes in expansion rate with different amounts of glass sand content and different particle sizes of glass powder in mortar rods were compared, and the effects of glass sand content and the glass powder particle size on the expansion of ASR were analyzed. SEM was used to compare and analyze the microstructure of mortar rods to explore the mechanism of ASR expansion of glass concrete, and the results showed that the addition of glass powder had a certain inhibitory effect on ASR expansion. The larger the particle size of glass powder was, the better the inhibition effect on ASR expansion and the longer its duration. Compared with the three groups of experiments of 0–13 μm, 13–38 μm, and 38–75 μm, it was found that the influence of the glass powder particle size on the expansion of ASR was weaker than that of dosage. The inhibitory effect of glass powder on ASR expansion is related to the fact that glass powder is more involved in pozzolanic reaction in the early hydration process.

Analysis of Porous Structure in Autoclaved Materials Modified by Glass Sand

This paper describes the use of glass sand in the production of autoclaved bricks. Traditional autoclaved materials consist of SiO2, CaO, and H2O. The purpose of the tests is to analyze the possibility of using glass sand in autoclaved materials and to determine their properties and durability. Depending on the structure, building materials can have porosities ranging from 0% (glass, metals) to over 90% (thermal insulation materials such as aerated concrete). Porosity of materials is directly related to the strength of materials and their density, and further to the thermal and acoustic insulation properties of products used especially for external wall construction, i.e., bricks, concrete, and aerated concrete. This type of silicate brick is formed at a temperature of 203 °C, therefore the dominant phase forming the microstructure is tobermorite, in contrast to the C-S-H phase, which dominates in concretes and which is characterized by a larger specific surface. The nature of pores, their number, appearance and arrangement in the material can be studied using computer techniques (SEM, XRD, computed tomography, porosimetry). Computed tomography (micro-CT analysis) showed that the number of voids in the material modified by glass sand is about 20% in relation to the weight of the product. The density of the product with glass sand was determined to be 2.2 kg/dm3.

Effects of Waste Soda-Lime Glass Sand and Glass Fiber on Physical and Mechanical Properties of None-Autoclaved Aerated Concrete

This paper investigates the combined effect of waste soda-lime glass sand and glass fiber on the physical and mechanical properties of none-autoclaved aerated concrete (NAAC). The use of both soda-lime glass sand and glass fiber can provide silica-rich materials in the aerated concrete and can enable the elimination of an autoclaved curing by enhancing the physical and mechanical properties in aerated concrete. In this study, a total of six mixture proportions were designed to evaluate these properties in NAAC. The mixture parameters included the partial substitutions of normal sand with soda-lime glass sand (0%, 15%, and 30%) and glass fiber (1%, 2%, and 3%). A series of tests were conducted to determine density, absorption, porosity, and both compressive and flexural strengths of the NAAC. Test results present that the increase of glass sand content leads to the increasing of both compressive and flexural strengths. Moreover, the combination of the use of glass sand with glass fiber also increases the strength up to 2 times (the mixture of 30% glass sand and 3% glass fiber). Furthermore, test results indicate the relatively good relationship between the density, porosity, and of NAAC with good accuracy.

Automated batch settling column with vibrated rods and evaluation protocol for living waters mud thickening

Gravity solid-liquid phase separation is applied in minerals industries, waste water treatment, filtration, sewage, drinking water, ocean (water) engineering, dredging, environment and biotechnology. The healthy nation of freshwaters like Lake Balaton and River Bodrog can be maintained by regular mud dredging. The on-water pure mechanical mud thickening would be a really beneficial technology. A new automated batch settling column with vibrated rods had been developed and fundamental tests had been carried out with model materials (glass sand) and muds (Siofok, Tihany, Tokaj). A numerical evaluation protocol with spline interpolation and derivation had been developed by with simple key parameters were determined. Results can be used for the design of a new type of thickener called the rod-lamella thickener.