Microstructure Properties Of Mortars Research Articles

Development of novel mortar using fine river sand and pretreated waste flue gas desulfurization gypsum powder and pond fly ash

The objective of this study is to investigate the potential of combined pond fly ash (PFA) and flue gas desulfurization gypsum (FGDG) as a partial replacement for cement by mixing them with fine river sand for green mortar development. We studied the physical, mechanical, and microstructural properties of mortars by using techniques such as scanning electron microscopy equipped with energy-dispersive X-ray spectroscopy (SEM-EDXS) and X-ray diffraction (XRD) for chemical component identification of the hydrated phase. These experimental results show that mortar containing pond fly ash, FGDG, and cement concentrations of 5 wt%, 5 wt%, and 90 wt% yields the maximum compressive strength (8.9 MPa) and flexural strength (3.4 MPa) after 28 days. This mortar has 12.6% higher compressive strength and 48% lower shrinkage in comparison with control specimens. A reduction in shrinkage is attributed to the denser structure of the mortar, as the calcium silicate hydrate (C–S–H) gel is found to exist in the SEM image and also identified through XRD studies. It is also concluded that excessive ettringite formation causes expansion in the volume of mortar, voids formation, and results in the reduction of strength. The application of this mortar can be in the internal plaster, bricks, and masonry.

An Investigation of the Effect of Waste Glass Additive on Strength and Microstructure Properties of Mortars

The importance of recycling waste in terms of ecological efficiency becomes more evident every day. Cement based mortars are one of the building materials that are widely used in building production. Especially the energy and raw materials consumed in cement production are important in terms of ecological efficiency. Savings in the amount of cement in cement-based mortars will be beneficial in this sense. With this perspective, in this study, the usability of waste glass in mortar production was investigated experimentally. Following the production stage of the test specimens, workability measurements were made first. Compressive and flexural strength tests were performed on the produced mortar samples to determine their strength properties. Microstructural examinations were carried out using the SEM technique. Unlike other studies, morphological findings were detailed with the help of EDX analyses. As a result, with the addition of waste glass, a decrease in the strength values of the test specimens was determined. It was also found that glass wastes with 10% substitution rate improved the workability.

Influence of Nanoparticles and PVA Fibers on Concrete and Mortar on Microstructural and Durability Properties

Nanoparticles are one of the effective methodologies implemented in concrete technology. The main objective of this research is to study the influence of nano alumina with different percentage variations ranging from 1% to 3% along with the incorporation of PVA fibers. From the mechanical properties test, the optimum dosage was determined to further study the durability behavior. This research work also investigates the hybridization of two nanoparticles such as nano silica (NS) and nano alumina (NA). The results show that the increasing quantity of NA reduces the compressive strength of the mortar due to agglomeration (cluster of particles), which results in a greater molecular attraction force. From the test results, it is concluded that the optimum dosage has been attained with an addition of 2% NA with 0.3% PVA. The compression strength test results at 14 days and 28 days reveal that the addition of NA tends the mineral admixture to react at early ages in the hydration process, which produces a new chemical compound to fill the pores. The rapid chloride penetration (RCPT) test results at 28 days significantly improved with the incorporation of nanoparticles due to their effective size and chemical reaction towards the other compounds. The test results from the hybridization of nanoparticles showed that the compressive strength was significantly enhanced compared to that of the control mortar and mortar with NA. They are effective up to certain limits beyond that addition, and the workability was reduced. Amongst all mixtures, the maximum compression strength has been attained for the mix with the addition of NA 0.5% and NS 2.5% comparatively. The microstructural properties of mortar were also studied through scanning electron microscope (SEM) analysis. The results showed that the incorporation of nanoparticles in the mortar matrix turns homogeneous with fewer pores and greater amount of hydration compounds; thereby, pore refinement has improved the hydration compounds remarkably.

Investigation on the properties of sustainable alkali-activated GGBS mortar with nano silica and dredged marine sand: Mechanical, microstructural and durability aspects

In recent years, alkali-activated mortar (AAM) has emerged as a promising alternative to ordinary Portland cement (OPC) due to concerns regarding the environmental impact resulting from cement production, which releases carbon dioxide and degrades the quality of the environment. To address these concerns, researchers have explored the addition of supplementary binder materials to enhance cement properties and mitigate pollution. The effectiveness of these binder materials depends heavily on their chemical composition and fineness. Notably, ground granulated blast furnace slag (GGBS) enhances the strength and durability of the cement. In response to the scarcity of river sand (RS), dredged marine sand (DMS) has gained popularity as a potential substitute within the civil engineering field. Furthermore, the integration of nanomaterials has shown promising improvements in the mechanical and microstructural properties of mortar. Therefore, this study aims to investigate the properties of mortar by incorporating nano silica (NS) within the range of 1% to 7%, varying the molarity from 2 M to 8 M, and substituting RS with DMS. The tests carried out encompass a range of evaluations, including compressive strength, flexural strength, SEM-EDS, XRD, UPV, RCPT, and carbonation analysis, to comprehensively assess the properties of the mortar. The study reveals that the AAM demonstrates optimal performance when 50% of RS is replaced by DMS in the absence of NS. Once this optimal point is determined, further analyses are conducted at this value while varying the concentrations of NS from 1–7%. The experimental results indicate that replacing 50% of RS with DMS and incorporating 6% NS leads to maximum compressive strength (49.2 MPa) and flexural strength (9.36 MPa) in the assessed properties. Furthermore, the incorporation of NS in GGBS-based AAM mixes enhances durability by improving resistance against chloride penetration, reducing water absorption, and minimizing carbonation diffusion. Additionally, the microstructural and mineralogical characterization of GGBS-NS-based AAM specimens demonstrates the formation of C-S-H and C-A-S-H gels as the end products of the reactions.

Mechanical, durability, and microstructural properties of mortars containing spent mushroom substrate as partial fine aggregate replacement.

Replacing conventional fine aggregates with spent mushroom substrate (SMS) is aimed at developing a sustainable lightweight masonry mortar. It is also an alternative solution for the current improper mushroom waste disposals. Density, workability, compressive strength, specific strength, flexural strength, ultrasonic pulse velocity, water absorption, sorptivity, and equivalent CO2 emission in relation to sand reduction in mortars containing 2.5-15.0% (by volume) SMS passing through a 4.75-mm sieve were investigated. As the percentages of replacement increased from 2.5 to 15.0%, the density of the SMS mortar reduced up to 34.8%, with corresponding compressive strengths of 24.96 to 3.37 MPa. Mixes with up to 12.5% SMS met the minimum compressive and flexural strengths as stated in the ASTM C129 standard. In addition, the equivalent CO2 emission of the mixes reduced 15.09% as the SMS content increased while cost-effectiveness increases up to 98.15% until 7.5% SMS replacement. In conclusion, the use of SMS as fine aggregates up to 12.5% is a viable mix design strategy for producing sustainable lightweight mortar with a lower carbon emission.

Effect of alum sludge ash on the high-temperature resistance of mortar

The effect of high temperature on the mechanical, durability, and microstructural properties of mortar containing alum sludge ash (ASA) was investigated in this paper. The ASA was derived from grinding and calcinating alum sludge, a typical by-product of the drinking water treatment processes. Four different mortar mixtures with ASA content at weight percentages of 0%, 10%, 20%, and 30% (as cement replacement) were exposed to high temperatures of 300 °C, 550 °C, and 800 °C, respectively. The experimental results showed that mortar samples containing up to 20% of cement replaced with ASA exhibited superior high-temperature resistance to the reference ones (without ASA), especially after exposure to 800 °C. The thermal analysis determined the portlandite consumption because of ASA pozzolanic reaction, and the x-ray diffraction pattern showed that the ASA reaction might contribute to the formation of aluminum-bearing phases with excellent refractoriness in the binder matrix. In addition, crack examination conducted by backscattered electron images evidenced that the ASA addition mitigated the binder paste degradation.

Mechanical, physicochemical, microstructural and self-cleaning performance of nano-titanium dioxide containing photocatalytic cement mortars exposed to elevated temperatures

In this study, the effect of thermal exposure on the mechanical, physicochemical, microstructural and self-cleaning properties of photocatalytic cement mortars was investigated. 1%, 2%, 3% and 4% of the ordinary Portland cement weight was replaced with nano-TiO2 particles. Mortars were heated at a rate of 2 °C/min to 200 °C, 400 °C, 500 °C, 600 °C, 700 °C and 800 °C. Compressive and flexural strengths, mass, water porosity, ultrasonic pulse velocity, optical microscopy, scanning electron microscopy, X-ray diffraction and thermogravimetric analysis tests were conducted before and after heating the mortars. The experimental results showed that nano-TiO2 particles have a significant influence on the residual properties of the mortars. The addition of TiO2 increased the resistance of the mortars to thermal deteriorations and preserved the residual mechanical, physicochemical and microstructural properties of the mortars. Additionally, for the first time, the influence of thermal exposure on the photocatalytic performance of cement composites was evaluated in this study by evaluating the degradation of rhodamine B. The photocatalytic performance was unaffected up to 400 °C, however, further heating deteriorated the photocatalytic performance of cement mortars.

Effects of ground basaltic pumice and high temperatures on the properties of HSMs

The mechanical and microstructural properties of high strength mortars (HSMs) containing ground basaltic pumice (GBP) subjected to 25, 300, 600, 900 and 1050 °C temperatures are investigated in this article. The mortars containing GBP employing the replacement ratio up to 25% GBP by weight of ordinary Portland cement (OPC) as well as a control mortar manufactured with OPC are produced. Two different cures, which are steam curing and pochette curing, are applied to the fresh mortars produced. The unit weight (ρ), ultrasonic pulse velocity (Upv), flexural strength (fs) and compressive strength (fc) of mortars containing GBP are investigated at the short/long terms and high temperatures. The microstructural properties of mortars containing GBP at high temperatures are also investigated by X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDAX) analyses. The results have shown that GBP can be successfully used instead of OPC in the mortar mixtures. Especially, the steam curing application has improved the mechanical properties of mortars containing GBP better than those of pochette curing.

Mikrostrukturna svojstva mortova koji se pripremaju od mješavine živog vapna

The effect of lime characteristics and hot lime mix method on hydraulic, microstructural and mechanical properties of mortars is determined by producing mortars from quicklimes of two different marbles and two limestones. Results of SEM-EDS, XRD and TGA analyses reveal that the porous microstructure of mortars and spongy texture of calcite crystals are the indicators of the hot lime mix method. This study shows that characteristics of limestones used for the production of limes, as well as the preparation method, directly affect hydraulic, mechanical and microstructural properties of mortars.

Microstructure and Strength Properties of Mortar Containing Waste Ceramic Nanoparticles

This study investigated the effects of waste ceramic powder on both the mechanical and microstructural properties of mortar. The study explored the utilization of $$\hbox {Al}_{2}\hbox {O}_{3}$$ – $$\hbox {SiO}_{2}$$ nanoparticles in mortar as cement replacement. Four mixes containing ceramic nanoparticles (0, 20, 40, and 60%) were prepared. The mortar specimens were tested for compressive strength. The role of ceramic waste powder was investigated through the analysis of microstructure in terms of scanning electron microscopy, X-ray diffraction, thermogravimetric analysis, and differential thermal analysis. The results revealed that the replacement of $$\hbox {Al}_{2}\hbox {O}_{3}$$ – $$\hbox {SiO}_{2}$$ nanoparticles to the mortar matrix had significantly enhanced the compressive strength. At 90 days, the compressive strength was in the range of 44.7–58.8 MPa. The results were validated through a microstructure test. The mortar with 40% of ceramic replacement showed better performance in terms of C-S-H production from active siliceous containing excessive calcium hydroxide content.

Combined effect of silica fume and expanded vermiculite on properties of lightweight mortars at ambient and elevated temperatures

In this study, properties of cement based mortars produced with vermiculite and silica fume were investigated at ambient and elevated temperatures. Physical, mechanical, thermal and micro structure properties of mortars produced were determined. Mortars were produced at 4, 6 and 8 expanded vermiculite/cement ratio (V/C) by volume. Silica fume was used at the ratios of 0%, 5%, 10% and 15% under each V/C ratio. In total, 114 mortar specimens with 40×40×160mm were investigated. Specimens were subjected to 300, 600 and 900°C for 6h. It was observed that new formulations with silica fume increased both strength and durability at elevated temperatures of mortars with vermiculite. Unit weights of mortars at hardened state range between 1200 and 780kg/m3. Water absorption values range between 24.2% and 40.6%. Strengths of mortars vary between 3.9MPa and 16.4MPa at ambient temperature. Thermal conductivity coefficient of mortars indicated a decrease depending on V/C ratio of mortar up to 0.257W/mK which means 58.2% increment in thermal performance. Mortars produced using expanded vermiculite aggregate shows a good performance in terms of preservation of mechanical strength to elevated temperature. This means that expanded vermiculite turns out to be a good fire resistant material.

WASTE GLASS POWDER-BASED ALKALI-ACTIVATED MORTAR

The global warming ensues from the emission of large amount of greenhouse gases in the atmosphere. The part of the carbon footprint attributed to the concrete becomes more and more important due to the cement content and the increase of the worldwide demand for concrete. Although much is done to reduce the environmental impact of concrete with the use of supplementary cementitious materials, the best alternative can be the development of new Portland cement-free binder through alkali-activation of waste products. This paper deals with the development of waste glass powder (GP) based alkali-activated mortar. Metakaolin (MK) is used to replace a part of glass powder in order to introduce Al and also to stabilize alkali ions in the system. The effect of NaOH concentration and MK content on the mechanical and microstructural properties of mortars are studied. Results show a gradual increase in the mechanical properties of the mortar with more cohesion between the paste and sand aggregates when MK is added up to 8%. In contrast, without MK or with less than 3% of MK content, the compressive strength decreases with the time with a poor cohesion between the paste and aggregates. Moreover, the NaOH concentration of 5M is enough to activate the studied system as a high level of concentration induces a delay in the geopolymer gel formation. According to the first results, this glass powder based geopolymer seems promising and further studies need to be carried out.

Influence of the pozzolanic fraction obtained from vitrified bottom-ashes from MSWI on the properties of cementitious composites

Municipal Solid Waste Incineration Bottom Ashes (MSWI BA) have been submitted to a thermal treatment leading to their complete vitrification. The composition and the pozzolanic activity of the vitrified, grounded bottom ashes is evaluated, as far as the mechanical and microstructural properties of mortars containing up to 30 wt.% of this fraction (on cement weight), as a replacement of the hydraulic binder. At sufficiently long curing times, modified composites exhibit higher mechanical strengths and lower porosity than those of the unmodified ones. The same mortars show lower permeation to chlorides and sulphates and the tendency to depress the expansion generated by alkali-silica reactions (ASR).