Ordinary Portland Cement Production Research Articles

Life Cycle Assessment of Ordinary Portland Cement Production in South Africa: Mid-Point and End-Point Approaches

Several environmental impacts are associated with cement production, ranging from high greenhouse gas (GHG) levels to high energy consumption (fossil fuel and electricity) to high resource usage. Due to the growing demand for cement in the industry and limited studies in South Africa, it is essential to evaluate the environmental impact of cement production in the South African context. In this study, an analysis of the production model of South African (SA) cement plants was carried out to quantify its impacts and decipher how they consequently affect lives, resources, and the ecosystem. This study carried out a Life Cycle Assessment (LCA) of cement using both the mid-point and end-point approaches of the Life Cycle Impact Assessment (LCIA). This study carried out a cradle-to-gate analysis of 1 kg of cement produced in a typical SA plant. The result showed that for every 1 kg of cement produced, 0.993 CO2 eq was emitted into the atmosphere; 98.8% was actual CO₂ emission, and its resultant effect was global warming, which causes changes in climatic conditions. Also, 1.6 kg of 1,4-Dichlorobenzene (1,4-DCB) eq was emitted into the air and water, which caused high toxicity in these media, and for every 1 kg of cement produced, 0.139 kg of oil eq was produced, and its effect was seen in fossil resources’ scarcity. The end-point result showed that 55,404 was the potential number of human lives that could be endangered annually; 133 species had the potential to be endangered annually, and the effect of a potential scarcity of resources caused a total marginal price increase of ZAR 6.2 billion due to these damages. In conclusion, this study prescribed mitigation and adaptation strategies to counter these environmental impacts.

Carbon-captured sodium hydroxide solution for sustainable alkali-activated slag

The escalating impact of climate change, primarily driven by greenhouse gas emissions, has prompted global efforts to achieve carbon neutrality. Ordinary Portland cement production contributes approximately 7% to global carbon dioxide (CO2) emissions, necessitating innovative approaches for its sustainable production. A novel method is introduced that utilizes a sodium hydroxide (NaOH) solution captured with CO2 as an alkali activator for ground granulated blast furnace slag (GGBFS); it can substitute for the cement in producing construction materials. The method integrates CO2-dissolved alkaline solutions into the activation process of GGBFS, which results in the production of sustainable alkali-activated slag materials. Various concentrations of dissolved CO2 in the NaOH-based activator were used to evaluate their impact on compressive strength, setting time, and changes in phase composition. The results demonstrate that higher CO2 concentrations lead to increased compressive strength, but an excess hinders early-age strength development. X-ray diffraction and thermogravimetry analyses explain the phase changes during carbonation, emphasizing the role of CO2 in forming calcite and enhancing C-S-H production. Additionally, the study quantifies CO2 uptake, revealing a linear relationship with dissolved CO2 concentrations.

Evaluation of Properties of Concrete Without Cement Produced Using Fly Ash‐Based Geopolymer

AbstractThe use of ordinary Portland cement (OPC) in the construction industry is inevitable. The huge production of OPC and its use in infrastructural development pose an environmental impact. Greenhouse gas emitted increases the global temperature and it is an alarming sign to everybody on the planet. Concrete is the most consuming material which is produced by using OPC and it is proven that OPC contributes a lot to CO2 emission. Hence in this study attempt is made to produce concrete by using environment‐friendly material like fly ash along with alkaline activators, which is termed Geo polymer concrete. The by‐product fly ash is widely available worldwide. It is a by‐product of thermal power plants. The use of fly ash in concrete produces less expensive and more cost‐effective concrete than concrete made up using OPC. Due to its high silicate and alumina content, fly ash reacts with an alkaline solution to create an aluminosilicate gel that binds the aggregate and results in high‐quality concrete. Fly ash is finer than cement, it occupies the pores of cement after hydration. This would result in denser concrete which gives higher strength. In comparison to ordinary concrete, fly ash‐based geopolymer concrete offers better resistance to aggressive environments and high temperatures. In the present study, an alkaline activator of molarity 8 is used to prepare geopolymer concrete. The test specimens are cast and cured for 28 days. Test results indicate that an alkaline liquid fly‐ash ratio (0.4) produces higher mechanical properties. Hence, geopolymer concrete produced in this study is found to be cost‐effective and environment friendly.

Industrial by-products-derived binders for in-situ remediation of high Pb content pyrite ash: Synergistic use of ground granulated blast furnace slag and steel slag to achieve efficient Pb retention and CO2 mitigation

Ordinary Portland cement (OPC) is a cost-effective and conventional binder that is widely adopted in brownfield site remediation and redevelopment. However, the substantial carbon dioxide emission during OPC production and the concerns about its undesirable retention capacity for potentially toxic elements strain this strategy. To tackle this objective, we herein tailored four alternative binders (calcium aluminate cement, OPC-activated ground-granulated blast-furnace slag (GGBFS), white-steel-slag activated GGBFS, and alkaline-activated GGBFS) for facilitating immobilization of high Pb content pyrite ash, with the perspectives of enhancing Pb retention and mitigating anthropogenic carbon dioxide emissions. The characterizations revealed that the incorporation of white steel slag efficiently benefits the activity of GGBFS, herein facilitating the hydration products (mainly ettringite and calcium silicate hydrates) precipitation and Pb immobilization. Further, we quantified the cradle-to-gate carbon footprint and cost analysis attributed to each binder-Pb contaminants system, finding that the application of these alternative binders could be pivotal in the envisaged carbon-neutral world if the growth of the OPC-free roadmap continues. The findings suggest that the synergistic use of recycled white steel slag and GGBFS can be proposed as a profitable and sustainable OPC-free candidate to facilitate the management of lead-contaminated brownfield sites. The overall results underscore the potential immobilization mechanisms of Pb in multiple OPC-free/substitution binder systems and highlight the urgent need to bridge the zero-emission insights to sustainable in-situ solidification/stabilization technologies.

Production of an eco-friendly concrete by including high-volume zeolitic supplementary cementitious materials and quicklime

The production of ordinary Portland cement (OPC) is one of the main global causes of CO2 release to the atmosphere. However, its availability and unique characteristics as a binding material make it difficult to be substituted by eco-friendlier materials. However, OPC partial replacement with pozzolanic materials is one of the best solutions to this problem. Hence, in this study, various types of high-volume zeolite were employed as supplementary cementitious materials (SCM), substituting the OPC by up to 50 wt.% in the composition of the created mortars. Besides, quicklime and inorganic accelerators were included in some of the mortar mixtures to improve the hydration reaction and enhance its speed. The mechanical, durability and durability in sea water properties were investigated. Although the usage of SCM caused a decrease in the mechanical and durability properties of the specimens, the addition of 10 wt.% quicklime palliated this degradation by enhancing by 40% the 28-days compressive strength of the specimens and by significantly improving their durability (porosity, freeze–thaw resistance and carbonation resistance). Moreover, the mixtures were proved to be resistance to aggressive ionic environments, since their compressive strength even increased after 28-day immersion in seawater, due to the additional formation of hydration compounds.

Neural Network Predictive Models for Alkali-Activated Concrete Carbon Emission Using Metaheuristic Optimization Algorithms

Due to environmental impacts and the need for energy efficiency, the cement industry aims to make more durable and sustainable materials with less energy requirements without compromising mechanical properties based on UN Sustainable Development Goals 9 and 11. Carbon dioxide (CO2) emission into the atmosphere is mostly the result of human-induced activities and causes dangerous environmental impacts by increasing the average temperature of the earth. Since the production of ordinary Portland cement (PC) is a major contributor to CO2 emissions, this study proposes alkali-activated binders as an alternative to reduce the environmental impact of ordinary Portland cement production. The dataset required for the training processes of these algorithms was created using Mendeley as a data-gathering instrument. Some of the most efficient state-of-the-art meta-heuristic optimization algorithms were applied to obtain the optimal neural network architecture with the highest performance. These neural network models were applied in the prediction of carbon emissions. The accuracy of these models was measured using statistical measures such as the mean squared error (MSE) and coefficient of determination (R2). The results show that carbon emissions associated with the production of alkali-activated concrete can be predicted with high accuracy using state-of-the-art machine learning techniques. In this study, in which the binders produced by the alkali activation method were evaluated for their usability as a binder material to replace Portland cement, it is concluded that the most successful hyperparameter optimization algorithm for this study is the genetic algorithm (GA) with accurate mean squared error (MSE = 161.17) and coefficient of determination (R2 = 0.90) values in the datasets.

Study on energy use and carbon emission from manufacturing of OPC and blended cements in India.

The demand for production of cements is ever increasing to meet the infrastructure development globally. The energy and emission factors available for cements in most of the life cycle assessment (LCA) databases may not exactly suit for all the geographical locations. The main challenge in Indian scenario is the absence of database for LCA study. This study attempts to develop the energy and emission factors for the manufacturing of cements in Indian context. In the present study, five different cement manufacturing plants located in north, south, east, west and central zones of India are considered to assess the energy dissipation and carbon dioxide emission involved during the production of ordinary Portland cement (OPC). Most of the data is collected from the field, so that the energy and emission factors determined will be suitable for the zonal study. The study is then extended to assess the energy consumption and carbon dioxide emission for three blended cements, viz. Portland Pozzolan cement (PPC), Portland slag cement (PSC) and composite cement (CC) with permissible known replacement levels of fly ash, granulated blast furnace slag and both fly ash and slag, respectively. The average energy use and carbon emission is found to be on higher side in India by 15.14% and 12.64%, respectively, compared to other countries in manufacturing of cements. An average energy consumption in manufacturing of PPC, PSC and CC is found to be respectively 24.5%, 35.3% and 43.13% less compared to that of OPC. The CO2 emission intensity for OPC is found to vary between 893 and 940kg/tonne of cement from five different zones, and an average of respectively 24.8%, 40.97% and 47.18% lower CO2 emission was observed from PPC, PSC and CC compared to OPC. From the inventory results, CC has proven to be a more sustainable cement with low energy consumption and lower CO2 emission compared to other cements.

The Effect of Adding Barley and Oats Husks Ashes on the Properties of Ordinary Portland cement

In this scientific study, the researcher’s analysed agricultural waste materials, namely barley husk ash (BHA) and oats husk ash (OHA), as possible substitutes for ordinary Portland cement (OPC). The primary aim was to improve OPC production capacity while mitigating ecological and economic problems linked with traditional OPC production. A range of cement blends, comprising different proportions (0, 5, 10, 15, 20 and 25 wt. %) of BHA or OHA additives in OPC, were prepared and analysed.
 Raw material analysis was conducted through X-ray fluorescence technique (XRF), complying with established standards. Cement mixes, resulting from the blends, were scrutinised for their cementing properties and mechanical performance according to international standards. The properties analysed were standard water of consistency (WOC), bulk density, apparent porosity and compressive strength after a hydration period of 28 days. A 15% ash inclusion resulted in the maximum compressive strength of hardened cement pastes, specifically, a 42% increase for reinforcing with BHA (strength value rose from 358 to 510 Kg/cm3) and a 38% increase in strength value for OHA incorporation (strength value increased from 340 to 470 Kg/cm3).
 The study's findings showed that the incorporation of 15-20 wt. % of BHA or OHA led to a substantial improvement in the cementing properties examined. It is noteworthy that BHA was found to be more advantageous as cement mixes containing BHA demonstrated superior cementing properties in comparison to the other investigated samples. The superior performance of the cement blends can be attributed to the relatively higher pozzolanic nature demonstrated by BHA, which had a positive impact overall.

Effect of manufactured sand, micro silica, and GGBS on properties of high-performance concrete

The most often used building material for engineering constructions is concrete. The rapid urbanization has necessitated the need for High Strength (HS) and High -Performance Concrete (HPC) for specialized constructions, such as high rise/tall structure and other important structures. Greater cement content may be required for concrete with higher performance like strength and durability, but code does not permit it, because higher cement content increases the heat of hydration, which leads to the development of thermal cracks in concrete, reduces its structural performance and damage environment by producing CO2 during production of Ordinary Portland Cement (OPC). This study tries to replace OPC by Micro Silica (MS) and Ground Granulated Blast Furnace Slag (GGBS) by some percentage to find our effect of these materials on properties of concrete HPC.In this work, the influence of Manufactured Sand (M-Sand), Micro Silica (MS) and Ground Granulated Blast Furnace Slag (GGBS) on the mechanical and durability qualities of High - Performance Concrete (HPC) is examined experimentally. Ordinary Portland cement (OPC) is used to create the HPC mixtures and then 40%,45%, 50% by weight of OPC is replaced with GGBS and 2.5% and 5% by weight of OPC is replaced with MS respectively. Additionally, OPC is replaced by 40%GGBS+ 2.5% MS, 40% GGBS+5% MS, 45%GGBS+ 2.5% MS, 45% GGBS+5% MS, and 50%GGBS+ 2.5%MS, 50%GGBS+5% MS. For each percentage replacement workability test, compressive test at the age of 28,56 and 90 days, water permeability test at 28 days and 90 days, Scanning Elector Microscope (SEM) test after 90 days are carried out. The investigative study’s findings showed that partial replacement of OPC with GGBS, MS, and combinations of GGBS and MS produces more consistent outcomes for strength and durability when compared to control mix.

Utilization of treated water for building construction: A case study in Egypt

Due to rising living standards and population growth, saving fresh water will be a significant problem for the next generation. The Government is indirectly impacted by a significant financial burden due to the current usage of treated wastewater, in all of Egypt's districts. As a case study, Egypt's new administrative capital was chosen, given that it is today one of the most important cities and that its planning was predicated on making it a smart, sustainable city. The goal of the study was to develop methods for replacing potable water in the manufacture of concrete with tertiary-treated wastewater; however, used for concrete mixing or curing after concrete hardening. Property assessments of the fresh and hardened concrete were conducted, to ascertain the best water quality that can be used without compromising the quality or durability of the concrete. ; The results of this paper will serve as a guide for decision-makers looking to decrease costs and increase sustainability by using treated wastewater in making sustainable concrete for buildings, especially in recent decades, rising construction material usage has generated considerable environmental difficulties, particularly in the production of Ordinary Portland cement (OPC).

Effect of coconut shell ash substitute with cement on the mechanical properties of cement concrete

The production of ordinary portland cement results in a great amount of carbon dioxide emissions, which has serious consequences for the environment. The building industry has been urged to make use of soil waste from industries or secondary materials in order to cut down on the amount of natural raw materials needed to make cement and concrete. Increases in population, economic activity, and social progress have all contributed to a rise in global garbage output. The investigation of waste reduction and reuse is one of the most alluring possibilities for handling such waste. It is becoming increasingly unaffordable to use cement in concrete works, despite the fact that the demand for homes and other constructions that rely on this material continues to rise in combination with the expansion of the human population; as a result, it is necessary to identify and develop alternative binding materials that can be used either wholly or partially in place of cement. In order to produce coconut shell ash (CSA), an agricultural waste material and environmental pollutant that is used as pozzolana in partial replacement of cement in the production of concrete, coconut shells are collected, burned in the open air (uncontrolled combustion) for three hours, and then incinerated in a muffle furnace at 800oC for seven hours. On the order of 0%, 5%, 10%, 15%, 20%, and 25% OPC was replaced with CSA in the concrete used to cast the specimens. Coconut shell ash is a viable cement replacement. The impact of CSA on mechanical qualities was investigated using a range of coconut shell ash replacements.

Recovery of ultra-high purity reactive magnesia from reject brine and its comparison with commercial magnesia

CO2 emissions and energy consumption associated with ordinary Portland cement production have increased the urgency for the development of alternative construction materials. Reactive magnesia cement (RMC) has been widely studied in the recent years due to the lower calcination temperature used during its production and its ability to permanently sequester CO2. In addition to the calcination of magnesite, reactive MgO, the main component of RMC, can also be synthesized from reject brine, which is rich in Mg2+. However, the presence of other components such as calcium in reject brine leads to the precipitation of other mineral phases together with Mg(OH)2, thereby reducing the purity of the final product. With the goal of improving the purity and yield of MgO synthesized at the end of this process, this study proposed a selective precipitation approach under a controlled pH. An optimum condition was determined for the synthesis of magnesium oxalate dihydrate with an ultra-high purity of 99.6 % and a high magnesium recovery rate of 94.1 %. Reactive MgO with a specific surface area of 30.2 m2/g was obtained after the calcination of the synthesized magnesium oxalate dihydrate at 700 °C for 2 h, which was higher than some of the commercially available MgO powders.

Novel Amorphous-Wollastonitic Low-Calcium Hydraulic Binders: A State-of-the-Art Review.

Because of the severe environmental impact of the CO2 emissions associated with the production of ordinary Portland cement (OPC) and the increasing demand for this commodity material, the development of alternative products has become a global concern. One alternative to OPC, or alitic-based clinkers, are amorphous-wollastonitic low-calcium hydraulic binders (AWLCs). This new class of hydraulic binders, described in the literature for the first time in 2015, may significantly reduce the CO2 emissions associated with its production, resulting from its lower calcium content, but also from the fact that its production technology can be fully electrified. In this paper, a state-of-the-art review is presented, providing a comprehensive description of the latest research, summarizing both the physicochemical and mechanical characteristics of this type of hydraulic binder, as well as possible routes for its production at an industrial scale.

Assessment of Use of Pozzocrete on Strength of Concrete

Abstract: Concrete demand has increased to satisfy the need of infrastructural development facilities. Tremendous amount of natural resources and energy is consumed for production of ordinary Portland cement. It also emits substantial quantity of carbon dioxide into the atmosphere. Therefore, it has been need of the hour to find out alternatives for making eco-friendly concrete. Many siliceous and alumnio-siliceous material are available which possess little or no binding values. But these materials in finely divided forms when come in contact with moisture, they chemically react with calcium hydroxide to form compounds those have binding properties. In the current studies when research was conducted on pozzocrete in laboratory it was well established that when pozzocrete is used in concrete, it increases the strength of concrete. Pozzocrete being finer than cement, gives more specific surface, fills the voids, increases workability of concrete and also reduces the problem of shrinkage in concrete. In the current study, the behavior of pozzocrete with cement concrete is reported. Percentage variation of pozzocrete in cement concrete to replace cement is tested to achieve economy as well as higher strength of RCC structural members. An experimental investigation was carried out on pozzocrete in reinforced cement concrete. Weigh batching method was used for 10% to 30% replacement of cement by pozzocrete in M20 grade concrete. It was found out that 30% replacement of cement with pozzocrete gave most acceptable results in flexural behavior. Workability and ductility of concrete was also found to be increased with increase in flexural strength.

Flexural Performance of RC Beam with the Partial Replacement of Cement with EggshellPowder(ESP)

Abstract: It's a renowned fact that concrete used around the globe is second only to water. The cement industries have been categorized as highly polluting industries by the Central Pollution Control Board (CPCB). The production of ordinary Portland cement contributes 5-7% of total greenhouse gas emission and also consumes large amount of energy, hence it is crucial to discover substitute to cement. Eggshell is a waste material that can be obtained from restaurants, bakeries and households. Eggshell powder (ESP) has high amounts of calcium and can be combined with pozzolanic materials, such as fly ash, which have low calcium content. If effective uses for eggshell can be found, it would create an opportunity for a sustainable solution. Eggshell waste is among the most abundant agro-waste material discharged from food processing industries. Despite the exceptional properties and several applications, eggshell is castoff in huge quantity without any further use. This review paper focuses on appraising the potential uses of eggshell waste as a feedstock for production of sustainable construction materials. The emphasis is on the need to exploit extensively eggshell waste as a partial cement replacement material in cement-based construction materials. This study focuses on the viability of using calcined eggshells (CES) as a partial replacement of cement by analysing early age performance. Compressive, Flexural and Split Tensile Strength of concrete with 10%, 15%, 20% cement replacement with eggshell powder. The utilization of PES which offers a low-cost and energy-efficient resource for construction.

Treatment of cadmium-contaminated soil using ladle slag with and without CO2

Cement and lime are widely used to stabilize/solidify (S/S) contaminated soils, however, the production of ordinary Portland cement (OPC) and lime causes CO2 emission and consumption of energy and non-renewable resource. In this context, this study proposes a sustainable S/S approach by utilizing an industrial by-product, ladle slag (LS), and carbon dioxide (CO2), to substitute cement and lime for treating cadmium (Cd)-contaminated soil. In laboratory investigation, contaminated soils spiked by Cd with concentrations of 0–32,000 mg/kg were treated by LS with a binder content of 10 % and subjected to conventional curing and carbonation curing for different periods varying from 3 hours to 112 days. The results showed that LS with conventional curing could reduce the leaching of Cd, however, it was still less effective than OPC in S/S of Cd-contaminated soils under the same curing period of 28 days. When CO2 was introduced, LS with CO2 rapidly decreased the leaching of Cd in soils by five orders of magnitude, using only 104 hours to achieve better S/S efficacy than OPC with conventional curing for 28 days. The LS with carbonation curing also sequestered CO2 up to 16 % of LS mass and yielded higher strength than that without CO2.

Axial compressive behaviour of GPC filled FRP Tubes: Experimental and analytical investigations

The production of Ordinary Portland Cement (OPC) releases carbon dioxide (CO2), which is one of the main contributors in the rising level of Greenhouse Gases (GHG) into the atmosphere and adversely effecting the environment and subsequently causing the climate change. In this study, the fly ash (FA) an alternative of OPC is used to produce environmental friendly cementless geopolymer concrete (GPC). This study investigates the axial compressive behavior of GPC filled fiber reinforced polymer (FRP) tubes. Two types of FRP tubes, i.e., carbon FRP (CFRP) tubes and glass FRP (GFRP) tubes were prepared by the wet lay-up procedure using CFRP and GFRP sheets, respectively. A total of forty-five GPC specimens of 150 mm diameter and 300 mm height were prepared with five different molarity of NaOH (8–16 M) with Na2SiO3 to NaOH ratio of 1.5. The unconfined GPC (Control), GPC filled CFRP tube (GCT) and GPC filled GFRP tube (GGT) specimens exhibited a significant increase in the peak axial stress (fc) with the increase in the molarity of NaOH. The scanning electron microscopic investigation also exhibited a reduced number of unreacted fly ash particles in the GPC with increasing the molarity of NaOH. The fc and corresponding axial strains (∊c) of GCT and GGT specimens were significantly higher than those of unconfined GPC specimens. The GCT specimens exhibited higher fc and corresponding ∊c than the GGT specimens. The analytical axial stress–strain (fc-∊c) curves of GCT and GGT specimens developed using available fc-∊c models of FRP confined ordinary Portland cement (OPC) concrete matched well with the experimental fc-∊c curves of GCT and GGT specimens.

State-of-the-Art Report: The Self-Healing Capability of Alkali-Activated Slag (AAS) Concrete.

Alkali-activated slag (AAS) has emerged as a potentially sustainable alternative to ordinary Portland cement (OPC) in various applications since OPC production contributed about 12% of global CO2 emissions in 2020. AAS offers great ecological advantages over OPC at some levels such as the utilization of industrial by-products and overcoming the issue of disposal, low energy consumption, and low greenhouse gas emission. Apart from these environmental benefits, the novel binder has shown enhanced resistance to high temperatures and chemical attacks. However, many studies have mentioned the risk of its considerably higher drying shrinkage and early-age cracking compared to OPC concrete. Despite the abundant research on the self-healing mechanism of OPC, limited work has been devoted to studying the self-healing behavior of AAS. Self-healing AAS is a revolutionary product that provides the solution for these drawbacks. This study is a critical review of the self-healing ability of AAS and its effect on the mechanical properties of AAS mortars. Several self-healing approaches, applications, and challenges of each mechanism are taken into account and compared regarding their impacts.

Microstructural and Mechanical Characteristics of Alkali-Activated Binders Composed of Milled Fly Ash and Granulated Blast Furnace Slag with µ-Limestone Addition.

Concrete is the most used construction material, needing large quantities of Portland cement. Unfortunately, Ordinary Portland Cement production is one of the main generators of CO2, which pollutes the atmosphere. Today, geopolymers are an emerging building material generated by the chemical activity of inorganic molecules without the Portland Cement addition. The most common alternative cementitious agents used in the cement industry are blast-furnace slag and fly ash. In the present work, the effect of 5 wt.% µ-limestone in mixtures of granulated blast-furnace slag and fly ash activated with sodium hydroxide (NaOH) at different concentrations was studied to evaluate the physical properties in the fresh and hardened states. The effect of µ-limestone was explored through XRD, SEM-EDS, atomic absorption, etc. The addition of µ-limestone increased the compressive strength reported values from 20 to 45 MPa at 28 days. It was found by atomic absorption that the CaCO3 of the μ-limestone dissolved in NaOH, precipitating Ca(OH)2 as the reaction product. SEM-EDS analysis showed a chemical interaction between C-A-S-H- and N-A-S-H-type gels with Ca(OH)2, forming (N, C)A-S-H- and C-(N)-A-S-H-type gels, improving mechanical performance and microstructural properties. The addition of μ-limestone appeared like a promising and cheap alternative for enhancing the properties of low-molarity alkaline cement since it helped exceed the 20 MPa strength recommended by current regulations for conventional cement.

High-performance eco-friendly ternary blended green concrete in seawater environment

The use of blended green concrete with improved performance has significantly increased in the industrial sector owing to the CO2 gas emissions and carbon footprint caused by the production of ordinary Portland cement. Although improvements have been continuously made, the deterioration of concrete structures in seawater poses a serious concern. The long term performance of green concretes in seawater environment are scarcely studied. Here we report the long-term strength, durability and anti-fouling properties of a novel blended eco-friendly concrete made with ordinary Portland cement, fly ash, nanoparticles, and corrosion inhibitor in natural seawater for one year. The mechanical strength, alkalinity, free chloride concentrations, biofouling attachment, and total viability count are studied. After a year of exposure to seawater, the ternary blended green concrete showed improved mechanical strength, a significantly lower chloride penetration and water penetration depth, a 70% reduction in free chloride content, a high calcium silicate hydrate content, and a four-order reduction in the total biomass. Our results suggest that the new concrete mix is promising for applications in seawater environments because of its improved mechanical properties, durability, and biofouling resistance.