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Sustainability is becoming increasingly pivotal in the construction industry, prompting a shift toward the use of bio-sourced waste materials. This study presents a novel application of mint stem (MS) waste as an additive in mortar with the aim of harnessing its cellulosic nature to enhance thermal insulation. The mineralogical and chemical properties of the raw materials were examined to understand their inherent characteristics and suitability for mortar composite development. The modified mortars were subjected to thermal and mechanical evaluations with MS proportions up to 6% by cement mass. The hot disk method revealed a substantial reduction in thermal conductivity (over 50%), whereas compressive strength testing indicated a decrease with higher MS content. The water absorption increased slightly, implying changes in porosity. These findings suggest that MS can play a significant role in the development of energy-efficient building materials, despite trade-offs in mechanical strength. This study discusses the implications of these results for sustainable construction and the potential of MS-enhanced mortar. [ABSTRACT FROM AUTHOR]

This paper presents an innovative study on the partial replacement of lime binder with foam glass dust to explore a new application of this waste dust as a lime mortar additive. Standard air lime mortars and natural hydraulic lime (NHL) mortars were made by incorporating from 0% to 40% of foam glass dust in replacement to lime, and their mechanical performances, microstructure, and durability were determined. The waste foam glass dust showed an unusually high pozzolanic activity, predicting an improvement in the mechanical properties and durability of lime mortars. As the replacement level in air lime mortars increased, the performance properties of the mortars improved. The pozzolanic reaction of foam glass dust did not compensate for the loss of hydraulic binder in NHL mortars; therefore, these mortars have gradually lost their strength. The progress in mortars carbonation, as well as the pozzolanic reaction of foam glass dust, led to the formation of denser and more frost-resistant structure in air lime mortars, whereas the partial binder replacement in NHL mortars with foam glass dust had no significant effect on their frost resistance. The highly effective use of foam glass dust as a supplementary material was assessed to air lime mortars. [ABSTRACT FROM AUTHOR]

Cement emulsified asphalt (CA) mortar is a key engineering material for ballastless slab tracks of high speed rail (HSR) and has a wide range of asphalt to cement (A/C) mass ratios. Depending on the A/C ratio, CA mortar may be composed of either cement-based or asphalt-based materials. In this paper, based on typical field service conditions of CA mortar of HSR and the characteristics of CA mortar, the testing conditions of dynamic mechanical thermoanalysis (DMTA) for CA mortar were determined, including by measuring the mode, specimen size, frequency, heating rate, and temperature range. Results show that DMTA characterized in this study indicates high repeatability and is an appropriate method for evaluating the thermodynamic mechanical properties of CA mortar. The vibration damping ability of CA mortar increases with an increase in asphalt content within a temperature range of (-40 to 60°C). [ABSTRACT FROM AUTHOR]

Existing test methods to assess alkali-silica reactivity of aggregates such as the accelerated mortar bar test (AMBT) has been shown to be less than satisfactory due to excessive false-positive and false-negative test results. While the concrete prism test (CPT) test is considered to be a more reliable alternative, the unusually long test duration (1 or 2 years, depending on the purpose) renders it unsuitable for routine evaluation of materials. This paper presents a new test method--the miniature concrete prism test (MCPT) that addresses the shortcomings of both the AMBT and the CPT test methods. The aggregates studied in this project were selected based on their established field performance. Results from this investigation indicate that the MCPT test method can reliably identify aggregate reactivity within a short duration of 56 days for the majority of aggregates, whereas it may take up to 84 days for some slowly reactive aggregates. [ABSTRACT FROM AUTHOR]

Perlite is a volcanic aluminosilicate abundant in several countries that are major producers of portland cement. The amorphous nature and silica-to-alumina ratio of ground perlite indicate that it can be activated with alkaline solutions. This study presents the strength development of mixtures containing only ground perlite as their powder binder, activated with sodium hydroxide and/or sodium silicate solutions, at room temperature or using oven curing. The structure of the formed geopolymers is investigated using X-ray diffraction, Fourier transform infrared spectroscopy, and nuclear magnetic resonance spectroscopy. The thermal stability and acid resistance of the mixtures are evaluated. Sodium silicate-activated mixtures slowly reach moderate strengths at room temperature but sodium hydroxide-activated ones do not develop strength regardless of activator concentration. Both activators produce geopolymers with high strengths with 100°C dry oven curing. Sodium silicate-activated specimens are more resistant to high temperatures but less resistant to a sulfuric acid solution than are sodium hydroxide solution-activated specimens. Being natural and having a more consistent chemical composition compared with most artificial pozzolans make perlite an attractive geopolymer raw material. [ABSTRACT FROM AUTHOR]

As part of a study into the controls on the deterioration of concrete due to sulfate attack, mortars (50-mm cubes and 40 x 40 x 160 mm prisms) made with portland cement CEMI, and 90% CEMI + 10% limestone blend were exposed to BRE DS4 sulfate solution based on magnesium sulfate (MgSO4 · 7H2O) under wetting and drying cycles for 18 months at 5°C. The effect of these cycles on thaumasite formation was studied and compared with samples immersed continuously in the same solutions. Visual observations and mass and length changes were used to assess the mortar deterioration, along with X-ray diffraction and infrared spectroscopy, which were used to determine the mineralogy of deterioration products. It was found that at 5°C, wetting and drying cycles significantly delayed thaumasite formation compared with control specimens. [ABSTRACT FROM AUTHOR]

This paper studies the effect of rice husk ash (RHA) in the properties of hydrated lime (calcium lime-CL90s) mortars with a view to improve their properties and make them more sustainable. The variation in mortar properties was related to the activity of the RHA, which was assessed by measuring its specific surface area, fineness, reactivity, composition, and amorphousness. According to the results, the RHA investigated is a low-temperature, highly reactive ash of high specific surface area that contains crystalline silica and unburnt cellulosic material and was probably produced between 400 and 500°C. Pozzolanic hydrates were clearly present after 24 h, progressively increasing in size and amount (at 3 and 7 days) and linking to each other to form continuous networks after 14 days. The paper concludes that lime replacement by RHA improves mortar workability, lowering water/binder ratio and the amount of water required to reach a specific consistency. RHA also enhances bulk density and lowers the difference between real and bulk densities thus resulting in lower porosity. Lime replacement by RHA enhances strength, and accelerates setting and early strength gain. Finally, with increasing RHA content, lime mortars become progressively stiffer and more elastic, yet remain plastic and thus undergo significant strain before failure. [ABSTRACT FROM AUTHOR]

In this study, quantitative analysis of the combined effects of fly ash and lithium admixture in mitigating alkali-silica reaction (ASR) in portland cement mortars prepared with Spratt limestone was investigated. The results from this investigation suggested that mortar bar expansions could be correlated with specific oxide(s) content in the fly ash through exponential relationships. The dosage of lithium nitrate required for ASR mitigation in mortars containing fly ashes having CaO content less than 23.50% was found to be less than that in the control mortars. Since lithium nitrate was found to be effective in reducing the expansions of control (no fly ash) mortars and mortars containing fly ashes, economic solutions can be obtained in both. However, the use of lithium nitrate was not needed for mortars containing fly ashes having CaO content less than 14.40%. A linear relationship between the oxide content of fly ash and the lithium dosage was found to exist, that can be used to optimize the lithium dosage as a function of fly ash composition to provide an economic solution for ASR mitigation. [ABSTRACT FROM AUTHOR]

Paper mill sludge is often incinerated for heat recovery and volume reduction. In Italy, about 600,000 t of paper mill sludge is produced yearly. About 6 kg of sludge is produced per ton of paper produced. The paper mill sludge is recovered from a primary mechanical separation process. When it is combusted as a single fuel source, it produces paper mill sludge ash (PA). In this project, PA was studied to evaluate its use as a supplementary cementitious material in mortars and concrete manufacturing. On the basis of the data collected, it was concluded that PA, if used to replace up to 10% of the portland cement, shows a positive effect on the mechanical performance of mortars. On the other hand, because of its high fineness and consequently high water absorption, it required a higher amount of water. It was concluded that the use of PA should not be higher than 10% by weight of the cement replaced, unless mortar mixtures are judiciously proportioned. [ABSTRACT FROM AUTHOR]