Source Of Supplementary Cementitious Materials Research Articles

Early-age properties of cement paste with mechanically ground Yellow River sediment

Yellow River sediment(YRS) is a rich, low-activity silica-aluminum dredged sediment resource, which can provide a new source of supplementary cementitious materials(SCMS). This study investigated the influence of mechanically ground Yellow River sediments (MGYRS) on the hydration kinetics and early-age shrinkage of cement paste. Hydration kinetics revealed that MGYRS could significantly accelerate the hydration process, proceeding directly from the nucleation and crystal growth stage (NG) to the diffusion stage (D). In the plastic stage of cement paste, the early-age shrinkage of MGYRS at 40 min and 70 min increased by 250 µm/m and 99 µm/m, respectively. Microscopic analysis showed that MGYRS could promote the generation of Ca(OH)2, and the nucleation, micro-aggregate filling effect of MGYRS could refine the pore structure. This study can provide theoretical support for realizing the gelatinization of YRS.

Future and emerging supplementary cementitious materials

To sustain the decarbonization of the cement industry, identifying new sources of supplementary cementitious materials (SCMs) is crucial. This review paper examines recent scientific literature on the understanding, assessment, and processing of future and emerging SCM resources. Among the SCMs that have generated significant interest are calcined clays, natural pozzolans, reclaimed coal fly ashes, certain biomass ashes, concrete recycling fines, and recycled glass. These SCMs are gaining market access, and their processing and performance have been well-established in local contexts.A growing body of research is considering a much wider array of by-product and waste materials as potential future SCM sources. These materials are often available in high volumes, but they typically require beneficiation processing to enhance their performance and compatibility as SCM. While promising results have been achieved for many materials, future research and development efforts are necessary to better understand their impact on cement and concrete properties and establish or improve the viability of the proposed beneficiation processing.In conclusion, this review highlights the latest developments in testing and specifications that support the uptake of a wider range of SCMs in cement and concrete.

Fly-Ash Evaluation as Potential EOL Material Replacement of Cement in Pastes: Morpho-Structural and Physico-Chemical Properties Assessment.

The main objective of the study was to produce alternative binder materials, obtained with low cost, low energy consumption, and low CO2 production, by regenerating end-of-life (EOL) materials from mineral deposits, to replace ordinary Portland cement (OPC). The materials analyzed were ash and slag from the Turceni thermal power plant deposit, Romania. These were initially examined for morphology, mineralogical composition, elemental composition, degree of crystallinity, and heating behavior, to determine their ability to be used as a potential source of supplementary cementitious materials (SCM) and to establish the activation and transformation temperature in the SCM. The in-situ pozzolanic behavior of commercial cement, as well as cement mixtures with different percentages of ash addition, were further observed. The mechanical resistance, water absorption, sorptivity capacity, resistance to alkali reactions (ASR), corrosion resistance, and resistance to reaction with sulfates were evaluated in this study using low-vacuum scanning electron microscopy.

Evaluation of Alternative Sources of Supplementary Cementitious Materials for Concrete Materials

This study characterized and evaluated the use of reclaimed fly ash (RFA) and reclaimed ground bottom ash (GBA) as alternative sources of supplementary cementitious materials (SCMs) for the production of concrete mixtures. Conventional Class F fly ash (FA) was also evaluated for comparison. The effects of SCM content on fresh and hardened properties of concrete were investigated by replacing 10%, 20%, and 30% of cement by mass. Characterization results showed that all three ashes met ASTM C618 chemical requirements (i.e., sum of SiO2 + Al2O3 + Fe2O3, CaO, SO3, moisture content, and loss of ignition) and 7- and 28-days strength activity index (SAI) requirements for Class F FA. In addition, RFA exhibited slightly higher SAI at 28 days of curing, followed by GBA and FA. In relation to fresh concrete properties, FA increased the concrete slump compared with the control mixture, whereas RFA and GBA decreased the concrete slump. However, GBA produced more significant slump decrements than RFA, which was attributed to the irregular angular particles of GBA. Generally, all the coal ashes produced decrements in air content compared with the control mixture. Comparatively, among the three ashes, GBA exhibited the highest 28- and 90-days compressive strength and surface resistivity (SR) at all cement replacement levels. Furthermore, at 90 days of curing, RFA and GBA concrete mixtures outperformed the FA concrete mixtures in relation to compressive strength and SR. Consequently, both RFA and GBA are promising SCMs for concrete materials.

Shear-thickening behavior of sustainable cement paste — Controlling physical parameters of new sources of supplementary cementitious materials

Cement is the main constituent of concrete and the world cement market represents more than 2 billion tons per year. However, the cement industry as a whole is the source of around 8% of global CO2footprint and therefore any reduction in the cement content can have a significant impact on reducing global CO2emissions. In terms of sustainability concept, Supplementary Cementitious Materials (SCMs) is one of the most common solutions given its great technical advantages for modern concrete, such as, rheological parameters adjustment, strength gain and full life durability, in addition to economical energy and low environmental impacts.In order to provide updated information for sustainable concrete design and preparation parallel with new sources of SCMs and on the other hand, the relationship between cement paste rheology and flow parameters of concrete. This present study investigates the shear thickening of sustainable cement paste (SCP) under control of some physical parameters of new sources of SCMs such as calcined diatomite (CD), calcined bentonite (CB) and silica fume (SF), respectively. Taking into consideration water-to-binder ratio (w/b) and high-range water-reducer (HRWR) based (PCE and PNS). It was observed that the shear thickening easily occurred when suspensions have a high anhydrous grains concentration, irregular shape, circular shape, high grains sizes (few tens of micrometers) and deflocculated grains state. Regardless of HRWR type and w/b ratios, flow index (n) of SCP substituted by CD is also larger than SCP with CB and SF with unvarying of SCMs level (10%). The intensity sequences of shear thickening of SCP under the influence of SCMs are CD, CB and SF, respectively.

Accelerated carbonation of ternary cements containing waste materials

Limestone calcined clay cement has great potential for reducing the environmental footprint associated with cement production. Few studies have explored ternary cement (TC) carbonation or the production of TC-containing waste materials. This study investigates TC carbonation using supercritical carbon dioxide (ScCO2) as an alternative method to accelerate the process. TCs were produced from waste raw materials, including wastes of clay brick (WCB), clay tiles (WCT), marble (WM), and phosphogypsum (PG). The formation of phases before and after ScCO2 attack were analysed using TG/DTG/DTA, XRD-Rietveld, and FTIR. The axial compressive strength, Rockwell surface hardness, and the advance of the carbonation depth were determined for different TC pastes. The results show that the aforementioned wastes can be used as alternatives to natural sources of supplementary cementitious materials (SCMs) to produce TC. Using WCB to replace calcined clay in TC resulted in the highest quantity of carboaluminates among the investigated pastes, in addition to high axial compressive strength and resistance to attack by ScCO2. The properties of the TCs were similar to those reported for limestone calcined clay cement in the literature, presenting less durability than Portland cement (PC) under carbonation by ScCO2 in the applied conditions. The calcined clay/limestone ratio influenced the behaviour of the pastes through changes in the C–H content. Increasing this ratio increased the extent of carbonation of WCT pastes and decreased the extent of carbonation of WCB pastes. The sustainability of TC can be improved via the use of waste materials.

Detoxified Spent Pot Lining from Aluminum Production as (Alumino-)Silicate Source for Composite Cement and AutoClaved Aerated Concrete

New sources of supplementary cementitious materials (SCMs) are needed to meet the future demand. A potential new source of SCM is spent pot lining, a residue from aluminum production. The present work showed that the refined aluminosilicate part of spent pot lining (SPL) has a moderate chemical reactivity in a cementitious system measured in the R3 calorimetry test, comparable to commercially used coal fly ash. The reaction of SPL led to the consumption of Ca(OH)2 in a cement paste beyond 7 days after mixing. At 28 and 90 days a significant contribution to strength development was therefore observed, reaching a relative strength, which is similar to composite cements with coal fly ash. At early age a retardation of the cement hydration is caused by the SPL, which should most likely be associated with the presence of trace amounts of NH3. The spent pot lining is also investigated as silica source for autoclaved aerated concrete blocks. The replacement of quartz by spent pot lining did not show an adverse effect on the strength-density relation of the lightweight blocks up to 50 wt% quartz substitution. Overall, spent pot lining can be used in small replacement volumes (30 wt%) as SCM or as replacement of quartz (50 wt%) in autoclaved aerated concrete blocks.

Ground and Sieved Bio Ash versus Coal Fly Ash: Comparative Analysis of Pozzolanic Reactivity

AbstractDue to the declining availability of coal fly ash, there is a need to identify alternative sources of supplementary cementitious materials (SCMs). This article presents an investigation on ...

Alternative supplementary cementitious materials for sustainable concrete structures: a review on characterization and properties

Currently, one of the main priorities for a government is to realize sustainable development. Strategies are required to protect the global environment, enhance employee health and safety, reduce emissions, and use fuels and raw materials responsibly across all sectors of the economy. Blended Portland cements containing supplementary cementitious materials (SCMs), usually industrial by-products, are excellent examples of industrial ecology. In particular, they offer a solution for reducing environmental impacts from several industries. In fact, with every ton of cement produced, nearly a ton of CO2 is emitted. The use of SCMs as a cement substitution reduces these CO2 emissions, saves non-renewable material sources, minimizes waste, and enhances the properties of the concrete. High-quality SCMs are becoming increasingly restricted. With the growing demands for cement, new sources of SCMs, often called alternative SCMs (ASCMs), will need to be used. However, this brings another challenge, as ASCMs are often comprised of local materials, with smaller volumes and more variable compositions. Accordingly, efficient and rapid methods are necessary for evaluating their performance and reactivity in concrete materials. Moreover, there is a need to characterize the chemical, physical, and mineralogical properties of the ASCMs. This paper presents the requirements for materials to qualify as SCMs, an example of a rapid screening test for assessing the performance of ASCMs, and an inventory of materials with favorable properties.

Hydration, strength, and durability of cementitious materials incorporating untreated corn cob ash

Significant research is being conducted to identify alternative sources of supplementary cementitious materials (SCM) worldwide. With the shortage of fly ash, due to the shut-down of several coal-fired power plants worldwide, there is an exigent need to identify sustainable SCMs that can replace fly ash in the concrete industry. This study explores the feasibility of using the ash of corn cob, which is the byproduct of one of the largest agricultural crops in the U.S., in concrete. Untreated corn cob ash (CCA) was prepared and used to replace the cement in concrete at replacement levels of 3% and 20% by mass of cement. The results of this study show that the untreated CCA significantly accelerated cement hydration, likely due to its high potassium oxide content. The results of reactivity testing suggest that the untreated CCA is less reactive than fly ash and that it is closer to an inert material. The concrete made with untreated CCA had significantly lower compressive strengths, lower bulk resistivity, lower formation factor, and higher electrical charge passed than normal concrete and what would typically be expected from the concrete with 3% and 20% replacements of inert materials. The results of this study suggest that untreated CCA is not a promising pozzolanic material, and may even be somewhat harmful to the concrete. A better option for the disposal of the large volumes of such materials could be for low-strength applications, such as fill or blocks. Alternatively, considering the significant variation in corn species and farming regimens, further research and ash treatment could help fine-tune the properties of this product for structural applications.

Agricultural Solid Waste as Source of Supplementary Cementitious Materials in Developing Countries.

Concrete production utilizes cement as its major ingredient. Cement production is an important consumer of natural resources and energy. Furthermore, the cement industry is a significant CO2 producer. To reduce the environmental impact of concrete production, supplementary cementitious materials such as fly ash, blast furnace slag, and silica fume are commonly used as (partial) cement replacement materials. However, these materials are industrial by-products and their availability is expected to decrease in the future due to, e.g., closing of coal power plants. In addition, these materials are not available everywhere, for example, in developing countries. In these countries, industrial and agricultural wastes with pozzolanic behavior offer opportunities for use in concrete production. This paper summarizes the engineering properties of concrete produced using widespread agricultural wastes such as palm oil fuel ash, rice husk ash, sugarcane bagasse ash, and bamboo leaf ash. Research on cement replacement containing agricultural wastes has shown that there is great potential for their utilization as partial replacement for cement and aggregates in concrete production. When properly designed, concretes containing these wastes have similar or slightly better mechanical and durability properties compared to ordinary Portland cement (OPC) concrete. Thus, successful use of these wastes in concrete offers novel sustainable materials and contributes to greener construction as it reduces the amount of waste, while also minimizing the use of virgin raw materials for cement production. This paper will help the concrete industry choose relevant waste products and their optimum content for concrete production. Furthermore, this study identifies research gaps which may help researchers in further studying concrete based on agricultural waste materials.

Characterization of Florida kaolin clays using multiple-technique approach

Abstract Kaolinite content of 10 raw Florida clays examined in this study was determined to be in the range of 70 to 90 mass %. This kaolinite content is sufficiently high for production of a potentially reactive pozzolanic material. The majority of the clays were at least partially disordered, which also indicates good pozzolanic activity of these materials after calcination. A good fit of the collected X-ray diffractograms during Rietveld refinement was obtained by using a combination of kaolinite, nacrite and dickite structures to allow modeling of stacking faults in kaolinite, adjusting for Fe3+ substitution and refining atomic coordinates. The results of kaolinite quantification were similar to those obtained by thermogravimetric analysis, which validates the proposed approach. Stoichiometric calculation also provided comparable results for all the clays, except for one sample where large overestimation of kaolinite content compared to X-ray diffraction and thermogravimetric analysis was observed. It was concluded that Florida clays present a promising potential source of supplementary cementitious materials for production of sustainable concrete.

Thermal Treatment of Kaolin: Effect on the Pozzolanic Activity

Thermally activated clays, especially kaolinitic clays, are today revaluated as a source of supplementary cementitious materials to reduce the CO2 emissions and energy consumption originated in cement production. In this work, the influence of different thermal treatments on the pozzolanic activity of raw kaolin with 98% kaolinite and ordered structure was studied. Results show that pozzolanic activity of calcined kaolin decays when using a thermal treatment at high temperatures (800 ¡C) and high periods of residence (30minutes). Furthermore, low calcination temperature (700 ¡C) must be corresponding with a residence time that guarantees a high dehydroxylation percentage. Sample treated during 10minutes (94%DH) was less reactive than the one treated during 30minutes (96%DH). Results contribute to the industry purposes to reduce the energy consumption, the CO2 emission and to contribute with new alternatives of sustainable development.