This study investigated the feasibility of Raman spectroscopy as a rapid and nondestructive chemical analysis tool for assessing radiation-induced amorphization in aggregate-forming minerals. Metachert and sandstone concrete aggregates, rich in quartz and containing additional minerals, such as albite and microcline in the case of sandstone, were exposed to various neutron fluence levels (1.2, 2.2, 7.0, and 14.3 x 10(19) n/cm(2), E >= 0.01 MeV) at similar to 53.3 degrees C. The Raman spectra of both the nonirradiated and irradiated samples were collected with a specific focus on quartz characterization. Concurrently, X-ray diffraction (XRD) refinement was employed to calculate the cell volume expansions of the studied mineral. The crystal lattice defects in alpha-quartz induced by neutron irradiation cause changes in the Raman band attributes (band position, full width at half maximum, and relative intensity), and are also responsible for the growth of defect bands. The behavior of the most intense vibrational bands can be used to estimate the change in the cell volume of irradiated alpha-quartz in different rocks. The data analysis presented in this study demonstrates a good correlation between the changes in the cell volume of quartz, as measured using XRD, and the Raman band attributes. This correlation enhances our understanding of structural alterations, emphasizing the potential of Raman spectroscopy as a reliable method for investigating the structural changes induced by the irradiation of minerals and highlighting its agreement with well-established XRD analyses.

This study investigates the preparation and performance of ExLDH, synthesized from Ca-Al layered double hydroxide (Ca-Al LDH) and polymethylmethacrylate (PMMA), as a cement additive to accelerate early hydration and enhance early strength in cement-based materials. The synthesized Ca-Al/PMMA LDH was characterized using X-ray diffraction (XRD), ATR-FTIR, SEM, TEM, BET surface area analysis, and dynamic light scattering (DLS). The composite incorporated into Portland cement at 1, 2, and 3 wt. % concentrations. Isothermal calorimetry assessed hydration heat over 72 h, while microstructural evaluation employed QXRD, ATR-FTIR, TGADTA, SEM, and water vapor sorption tests. Mechanical properties were evaluated through compressive and flexural strength tests. Results confirmed the successful fabrication of ExLDH micro/nano-composites, which serve a dual role in the cement matrix: acting as nucleation sites for hydrated phases and as void fillers to improve structural compaction. This dual effect accelerates hydration, increases hydrated phase content, and significantly enhances compressive strength and structural density.

In this study, a two-step carbonation method is developed to control the formation of calcium carbonate (Cc) polymorphs on the surface of recycled hardened cement paste (RHCP) without the use of chemical additives. In the first step, RHCP undergoes semi-dry carbonation under controlled humidity conditions, followed by wet carbonation at various temperatures in the second step. The results show that vaterite and aragonite are stabilized during the wet carbonation process, forming primarily on the surface of RHCP particles. The stabilization of the metastable Cc phases is driven by the synergistic effect of existing Cc seeds in the RHCP and the reaction temperature. A temperature range of 9-48 degrees C promotes the formation of vaterite, while higher temperatures (60-90 degrees C) lead to its dissolution. The calcite seeds present in RHCP do not enhance the formation of vaterite and aragonite during wet carbonation. This method offers a potential practical approach for valorizing concrete waste while capturing COQ from the atmosphere.

Cementitious materials generally have large carbon footprints because of the high CO2 emitted during Portland cement production. This is because limestone is used as an essential CaO resource, and its decomposition by calcination emits CO2. From this perspective, the concrete in urban buildings can be considered an urban mine of CaO resources. In this study, we propose obtaining a solidified product by crushing all the waste concrete, carbonating it, pressurizing it with a calcium bicarbonate solution, and drying it. The experimental results show that the bicarbonate solution, high-temperature conditions, and extended loading period produce a higher strength. In addition, neck growth at the contact surfaces of the carbonated concrete fines was confirmed using scanning electron microscopy. Consequently, the proposed method indicates that the hardening mechanism is the cold sintering of calcium carbonate on the surface of fine-carbonated concrete particles. This method allows the developed blocks to be used semi-permanently with relatively low energy consumption through repeated crushing and re-pressurization.

Mechanical strength of brick is significantly influenced by soil properties, deeming some soils unusable. This paper investigates the effect of mixing soils from different sources, Hyogo (a chlorite soil) and Tokyo (an albite soil) from Japan, on the flexural and compressive strength of unfired earth brick. Before conducting strength tests on moulded bricks made from original soil mixes and intermixed soils, both soil samples were individually separated into two portions, sand and fines. To better understand the strength behaviour of the resulting brick specimen, the physical and chemical properties of used raw materials were characterised using various techniques including X-ray computed tomography (X-ray CT) X-ray diffraction (XRD), water and nitrogen sorption, X-ray fluorescence (XRF) and ionic conductivity. The results revealed that the replacement of the fines portions in unadulterated soil mixes induced an increase in flexural and compressive strength for brick specimen made with albite soil, while significant reduction in strength was recorded with brick specimen made with fines portion replaced in chlorite soil. Furthermore, the former intermixed soil exhibited higher strengths than specimen made from unadulterated soils. Chlorite clay minerals comprised of desired properties to enhance performance of albite soil sand particles in a brick composite. This justified the dependence of selected soil parameters that play critical roles in the performance behaviour of the produced bricks. The obtained findings could serve as guidelines to production and performance enhancement of unburnt brick by amalgamating various soils.

This study investigates the alteration of felsic sandstone-type rock, which is used as a coarse aggregate in con-crete, subject to the effects of gamma-ray and neutron irradiation. The effects of three gamma-ray doses (27, 55, and 108 MGy) and four neutron fluence levels (1.22, 2.19, 6.99, and 14.30 x 1019 n/cm2, E & GE; 0.01 MeV) were investigated. Quartz and albite were found to be the major rock-forming minerals, with microcline intermediates, chlorite, and muscovite as the minors. Gamma rays caused no significant changes to the physical properties of the sandstone aggregates, even at high doses (108 MGy). In contrast, neutron irradiation caused alterations that became more pronounced at higher neutron fluences. The solid was confirmed to expand through metamicti-zation of the rock-forming minerals. Quartz and muscovite were the most affected phases, whereas albite and microcline intermediates were only slightly affected, and chlorite was almost unaffected. The decrease in density was measured by He and water pycnometry, and this value was almost reproduced by calculations using the rock-forming mineral composition of the pristine sample measured using X-ray powder diffraction/Rietveld analysis and the cell volume change of the major forming minerals. In addition, light optical microscopy and scanning electron microscopy images confirmed the presence of intergranular and intragranular cracks. Inter -granular cracks appeared to have initiated from the quartz grains, which expanded significantly. The intra-granular cracks were frequently observed in the albite and microcline intermediates. These cracks can be described as radial cracks starting from the expanding quartz, caused by enforced displacement for deformation consistency with quartz expansion. The crack area ratio quantified by SEM image analysis corresponds to the discrepancy of the volume expansion difference calculated by He or water pycnometry and dimensional change measurements. An evaluation of solid expansion and crack openings in aggregates is important to estimate concrete degradation.

Some organic compounds in phosphoric acid are a potential mediator of adverse environmental impacts on soil. This work aims to detect and reduce the content of organic compounds in crude phosphoric acid using waste sludge, from water treatment plants, as a low-cost sorbent. Gas chromatography/mass spectrometry (GC/MS) was used to detect the organic species in crude phosphoric acid, while X-ray fluorescence (XRF), X-ray Diffraction (XRD), scanning electron microscope equipped with energy-dispersive X-ray (SEM/EDAX) and attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy were used to characterise waste sludges. Practically, three sludge samples (S1 from El-Marg, S2 from Al-Obour and S3 from El-Sheikh Zayed stations, respectively) were utilised and different factors including shaking time, sorbent dose and phosphoric acid concentration were studied. The results of GC/MS revealed that crude phosphoric acid contains bis [tert-butyl(dimethyl)silyl] azelaate, dibutyl phthalate and 2,6-di-tert-butyl-4-methylphenol as the main organic species. Moreover, the clay content and the surface charge of sludge strongly affect the removal efficiency of organic species. Kinetic analysis using Lagergren pseudo-first-order, pseudo-second-order, Morris-Weber and Elovich models displays that the sorption process using waste sludges is a chemisorption process. The sorption capacity of the applied three sorbents was 26.3, 23.3 and 22.8 mg/g for S1, S2 and S3, respectively, which indicates that the three sludge samples exhibit potential sorbents for the clarification of phosphoric acid and sequentially to produce green phosphate fertilisers.

Contamination of aquatic ecosystems with radioactive nuclides is significantly threaten the human body. So, finding effective and economical sorbents is significant for uranium elimination from an aqueous solution is important. In this study, Cement kiln dust (CKD) is a solid waste produced during the cement production process was utilized as sorbent for the uranium sorption from an aqueous solution. The maximum adsorption of 156.2 mg g −1 at pH 3.0 which reflects good sorption properties for the CKD. All in all, the displayed data declares that the CKD material possess an extraordinary tendency for U(VI) recovery from aquatic environments.

Supplementary cementitious materials (SCMs) such as fly ash, silica fume, and waste glass powder (WGP) are widely used in concrete to reduce the emission of carbon dioxide and improve mechanical properties. Superplasticizers are added to ensure the workability of concrete, however, the effect of its type and dosage are very influential factors when concrete incorporates SCMs. Therefore, this study tries to fill the research gap and gain complete knowledge about the influence of a supplementary cementitious material, waste glass powder (WGP), on the compatibility of polynaphthalene sulfonate (PNS) or polycarboxylate (PC) based superplasticizers and ordinary Portland cement (OPC). Different blended cement mixtures are prepared and their standard water consistency and setting time is evaluated. The effect of waste glass powder content in the blended cement on the compatibility is studied through mini-slump test, zeta potential measurements and the mass of superplasticizers adsorbed on the surface of binder particles using total organic carbon (TOC) measurements. The results revealed that the presence of WGP has a great effect on the flowability and flowability retention time when PNS or PC were used as a superplasticizer. The adsorption behavior of both superplasticizers was altered where the amount of PNS adsorbed on the cement particles increased while that of PC decreased by increasing the percentage of incorporated WGP. The absolute zeta potential is significantly increased (in negative value) with the addition of PNS, but approximately not changed with the addition of PC. The change in adsorption behavior and the zeta potential measurement explained the compatibility of both superplasticizers with blended cement.

This study aims to investigate the feasibility of alkali activated slag as a sole binder for refractory concretes. The concrete samples prepared are subjected to different firing temperatures at 850, 1100 and 1300°C. The mineralogical compositions of the fired concretes are investigated using x-ray diffraction (XRD), and the microstructure is examined using scanning electron microscope (SEM). Also, sintering parameters, mechanical properties as well as refractory properties in terms of permanent linear change (PLC), refractoriness under load (RUL) and thermal shock resistance (TSR) are tested. Variation in sintering parameters and mechanical properties is observed by changing firing temperatures. Refractory concretes based on geopolymers exhibit significant PLC only at 1300°C, the maximum PLC index (0.56%) is observed under load and with an increase in temperature. In addition refractory concretes have a good TSR index (up to 15 cycles). According to XPAanalysis data within fired concretes apart from the main phases within aggregates, there are readily melting phases formed at 850 and 1100°C. Apparently with an increase in temperature there is formation of hibonite and anorthite. A needle-shaped structure is noticed embedded in glassy matrix at 110°C, but the plate-like structure of hibonite is observed at higher temperature. On the whole XPA results reveal that alkali activated slag cement is a promising binder for refractory concretes at high temperature.

This study aims to investigate the feasibility of alkaliactivated slag as a sole binder for refractory castables. The prepared castable samples were subjected to different firing temperatures at 850,1100 and 1300 °C. The mineralogical compositions of the fired castables were investigated using X -ray diffraction (XRD). The microstructure was examined using scanning electron microscope (SEM). Also, sintering parameters, mechanical properties as well as refractory properties in terms of permanent linear change (PLC), refractoriness under load (RUL) and thermal shock resistance (TSR) were tested. A variation in sintering parameters and mechanical properties is observed by changing firing temperatures. The geopolymer-based castables show a significant PLC only at 1300 °C, maximum expansion of 0,56 % under load and raising temperature and finally a good TSR up to 15 cycles. Phase analysis of fired castables confirmed, besides the main phases in aggregates, the formation of low melting phases at 850 and 1100 °C. Hibonite and anorthite were obviously observed with increasing the firing temperature. A needle-shaped structure is noticed embedded in glassy matrix at 110 °C, but plat-like structure of hibonite is observed at higher temperature. Overall, the results revealed that alkaliactivated slag cement is a promising binder for refractory castables at high temperature.

Modified polyethylene terephthalate polymers (MPETs), as a novel dispersing agent, were successfully prepared from polyethylene terephthalate (PET (flakes of empty bottles in order to recycle waste from one particularly abundance packaging material. Different techniques were used to characterize the MPETs samples, including attenuated total reflectance Fourier transform infrared (ATR-FTIR), gel permeation chromatography (GPC), differential scanning calorimetry (DSC), scanning electron microscope (SEM), dynamic light scattering (DLS) and Brunauer-Emmett-Teller (BET) surface area. The fluidity and mini-slump retention of fresh cement paste were tested to evaluate the dispersion capability of the MPETs. The effect of MPETs on the setting time and compressive strength of the cement paste were studied. The adsorptive behavior of the MPETs dispersions was examined using total organic carbon (TOC) and zeta potential to interpret the interaction of the MPETs with cement. The results show that the MPETs can be adsorbed on the cement particles and improve the flowability, setting time and the compressive strength of cement paste. Adding value by generating a cheap and effective dispersing agent from recycling waste polymers is a great approach toward eco-friendly waste management.

The alkaline activator has a significant effect on the microstructure and mechanical properties of fly ash-based alkali activated products. This paper aims to identify the reaction products of fly ash (FA) activated with alkaline activators of different concentrations of Na2O and different SiO2/Na2O ratios. NaOH solution (NA), a mixture of NaOH and sodium silicate solution (MIX) and sodium silicate solution (LG) were used to activate fly ash. Different techniques were used to characterize the reaction products of activated fly ash including X-ray diffraction (XRD) with Rietveld refinements, attenuated total reflectance Fourier transformer infrared (ATR-FTIR), Si-29 dipolar-decoupling (DD) magnetic angel spinning/nuclear magnetic resonance (Si-29 MAS/NMR) and Al-27 MAS NMR, field emission scanning electron microscopy (FE-SEM) attached with energy-dispersive X-ray (EDX) analyzer. Also, the fly ash-based alkali activated products were indentation tested using a Vickers indenter. The results revealed that the main reaction product of alkali activation of fly ash is a sodium aluminosilicate gel (geopolymer) with high Si/Al ratio when sodium silicate was used as alkaline activator, while zeolite appeared as minority phase when fly ash was activated with NaOH solution or a mixture of NaOH and sodium silicate solution. Moreover, Na2O content and SiO2/Na2O ratio in the activator solution influence on the amount of amorphous phase and Q(4)(mAl) units formed in the alkali activated materials and that reflect on the mechanical properties.

A sandy soil was stabilized by 10% CEM I 42.5 R. Up to 50% of the cement was replaced by waste glass powder, cement kiln bypass dust or activated clay. Polynapthalene sulfonate superplasticizer was used to increase the fluidity of the mixes. The flowability is measured by means of the flow table according to ASTM C230. The compressive strengths of cubic samples are recorded. It is found that the fluidity of the soil increases with increasing the superplasticizer dosage. A 90-day strength of 6.0 N/mm(2) is obtained by replacing 25 wt.% of the cement with waste glass powder using a w/b ratio of 1.5 and 2% superplasticizer. Segregation occurs with higher glass content. The use of cement dust as cement replacement material leads to lower strength values. Stabilization of the soil by 5% cement, 10% activated clay or glass powder, 5% cement dust, with 3% superplasticizer, produces castable mix with a 28d-strength of similar to 20 N/mm(2) when cured in water. This value decreases drastically in absence of cement.

Adhesion of residual packed materials to waste glass bottles, as well as particle size, pozzolanic activity and alkali-silica reaction (ASR) of waste glass powder, are important indexes to choose waste glass bottles to be utilized as supplementary cementitious materials (SCMs).Five different sources of waste glass bottles were selected, characterized and tested to be used as supplementary cementitious materials. The pozzolanic behavior of waste glass powders was examined by different methods. The compressive strength development of mortars containing uncolored, green or brown soda-lime ground glass types exhibited good pozzolanic behavior confirmed by a chemical test. The formation of calcium silicate hydrate (CSH) was demonstrated by XRD and TGA-DTA analysis. The alkali-silica reaction was monitored for the five glass powders.The results of pozzolanic activity, as well as the expansion results due to ASR, show that the powder of uncolored, green and brown soda-lime glass types is acceptable to be used as SCMs and the ions responsible for the color have no effect on the performance.

Rice straw ash was prepared by burning washed straw 90 minutes at 500 degrees C. Its major inorganic constituent was 72% silica and low potassium content of 1.2%. XRD has shown that the main crystalline constituent was calcite and in minor quantities sylvine and quartz. It showed high tendency to react with lime and a strength reactivity index was 82%. In accordance with the literature, the highest compressive strength of the mortars made of cement/ash binder was in the samples in which 10% of ash was replacing cement. The water demand and the setting time of the cement pastes was increasing with the ash addition; the flowability, porosity and water absorption of the respective mortars was decreasing. The low content of carbon have little effect on the behaviour and strength of cement with ash mortars, even without rice straw washing.

The mechanism of thaumasite formation is studied in a solution of sodium silicate and ettringite stored for 12months at 7°C. After 7months, the mix was carbonated by bubbling CO2 gas and the pH decreased from 11 to 9.5; at the 9th month the pH was raised again to 12.5 by adding lime water. The phases formed at the different pH ranges were identified by means of X-ray diffraction and infrared spectroscopy.