Traditional Portland Cement Research Articles

Experimental Study on the Synergistic Solidification of Soft Soil with Ceramic Powder–Slag–Phosphorus Slag

The bearing capacity of silt soft soil is poor, making it difficult for it to be used as a subgrade material in foundation engineering, and the use of traditional Portland cement curing agents causes environmental pollution. In this study, a new soft soil curing agent, CSP (ceramic powder–slag–phosphorus slag), was prepared using ceramic powder, slag, and phosphorus slag. The unconfined compressive strength of 7-day was determined via an orthogonal test, and the optimal ratio of the curing agent was determined. The effects of the initial water content, curing agent content, admixture type, and admixture content on the mechanical properties of solidified soil were investigated via a uniaxial compression test. The microstructure characteristics of the solidified soil were analyzed via XRD and SEM-EDS, and the mechanism by which ceramic powder–slag–phosphorus slag acted as a curing agent to increase the strength of the soft soil was explored. The results show that the optimal ratio of the curing agent for the inorganic binder is ceramic powder/slag/phosphorus slag = 3:2:1, the best water glass modulus is 1 mold, the best water glass content is 26%, and the 7-day compressive strength can reach 2.382 MPa; the strength of the solidified soil decreases with an increase in the water content and increases with an increase in the curing agent content. When the water content is 35% and the curing agent content is 14%, the strength of the solidified soil can meet the requirements of relevant specifications. When the content of triisopropanolamine was 2.0% and 1.5%, the compressive strength of the 7-day and 28-day solidified soil specimens increased most significantly. The ceramic powder–slag–phosphorus slag can promote the formation of aggregates and amorphous hydration products (C-S-H, C-A-H), be distributed on the surface of the soil and fill the pores, and enhance the cementation between the particles, improving the compactness of the soil structure. In terms of the macroscopic performance, the mechanical properties of the solidified soil were significantly improved. Therefore, CSP curing agents can be promoted and applied as green, economical, environmentally friendly, and low-carbon curing materials in soft soil roadbed engineering.

Effect of varied waste concrete ratios on the mechanical properties of polymer concrete

Abstract Polymer concrete (PC) was developed at the end of the 1950s and gained popularity in the 1970s for precast parts, flimsy floor coverings, and repairs. Due to its superior performance over traditional Portland cement concrete, which offers many benefits, including mechanical properties, quick hardening, and durability. In this article, polymeric concrete was made using a mixture of sand and epoxy, and different proportions of sand were replaced with crushed concrete waste. This study found that the ideal ratio between resin and fine aggregate was 23% resin to 77% fine aggregate in terms of the total weight of the combination to get the best dispersion of fine aggregate. Waste concrete replaced 5, 10, 15, and 20% of aggregate in PC, respectively. It was further demonstrated that increased waste concrete aggregate content in PC increased the 28-day compressive strength by 7.7, 13.44, 16.8, and 18.97%, respectively; flexural strength increased by 16.68, 25.32, 37.16, and 47.71% at 28 days’ age; and direct tensile strength was higher than the reference mixture by values of 3.41, 17.21, 23.54, and 30.38% at 28 days age. The findings recommended using recycled fine aggregate on PC and suggested a 20% replacement ratio as an optimum percentage.

Experimental investigation and numerical modeling on mechanical behavior of highly porous cement-based material: An overview

This paper presents an overview of recent developments in experimental investigation and numerical modeling of highly porous cement-based materials, focusing on traditional Portland cement (PC) and geopolymer foam concrete. It starts by introducing the advantages of using highly porous cement-based materials compared to their dense counterparts and then delves into the properties of PC and geopolymer foam concrete. The first part of the review is dedicated to the experimental investigation, including mixture proportions, foaming methods, mechanical properties and air-void systems. This part also summarizes and discusses various strength prediction models for foam concrete that were drawn from experimental data. The second part of the review is dedicated to the computational methods used to simulate porous materials, and attention is focused on continuum-based and discrete-based approaches. Finally, the failure mechanism of porous cement-based materials is discussed, along with comparing the failure criteria for both dense and porous cement-based materials.

Fiber-Reinforced Alkali-Activated Cements from Ceramic Waste and Ladle Furnace Slag without Thermal Curing

Alkaline-activated cement, as an alternative to conventional portland cement, is being increasingly studied due to its environmental advantages and engineering properties. However, research on the feasibility of using both uncommon precursors and curing at ambient temperature is still limited. This study aims to investigate the potential of ceramic wastes, specifically from brick and tile production and ladle furnace slag, as precursors in alkaline activated cement reinforced with polyacrylonitrile fibers cured at 20°C. Sodium silicate, in solution form, was used to activate the precursors, and three different fiber contents were tested, namely 0%, 0.5%, and 1%, by volume. Physical properties, such as capillarity and porosity, were assessed. Moreover, the mechanical behavior was thoroughly characterized by uniaxial compressive, flexural, and elasticity modulus tests. In addition, a thorough microstructural characterization, including scanning electron microscopy, X-ray energy dispersive analyzer, X-ray diffraction, and Fourier transform infrared spectroscopy was conducted at 14, 28, and 90 days. The results revealed that environmentally friendly alkali-activated binders were produced from wastes with limited industrial recycling possibilities. The mixture with 0.5% fibers was the one that presented better results, i.e., a flexural strength of 8.84 N/mm2 and compressive strength of ∼29 MPa at 90 days. The mechanical performance of this material is relevant, especially considering that a relatively low curing temperature was applied. The results also showed that calcium aluminum silicate hydrate (C-A-S-H) was detected as the main reaction product.Practical ApplicationsAlkali-activated cement has been identified as a potential alternative to traditional portland cement due to advantages such as the reduction of CO2 emissions to the atmosphere, and the conservation of natural resources, because wastes can be transformed into useful products. All over the world, ceramic materials are widely used in different types of construction, and significant amount (between 30% and 45%), end up as waste. Therefore, this study aims to show the possibility of reusing ceramic waste for the development of a fiber-reinforced alkaline activated cement composite with acceptable physical and mechanical properties that allow it to be used in non-structural applications; for example, bricks, tiles, partition walls, and other building materials. It also is a low-energy consumption process, because curing can be done at ambient temperatures. Finally, the obtained results, e.g., flexural strength of 8.84 N/mm2 and compressive strength of 29 MPa, open the door for several applications in the construction industry.

Retarding Effect of Hemp Hurd Lixiviates on the Hydration of Hydraulic and CSA Cements.

Wood wool panels are widely used in the construction industry as sustainable cementitious composites, but there is a growing need to replace traditional Portland cement with a binder that has a lower embodied carbon footprint. In addition, the sustainability of these panels may face serious impediments if the required amount of wood for their production needs a harvest rate higher than the rate at which the tree sources reach maturity. One solution is to use the wooden part of fast-growing plants such as hemp. However, the compounds extracted from the mixture of plants and water are the main cause of the delay observed during the hydration process of hydraulic binders in these cementitious composites. The objective of this study is to evaluate the effect of bio-aggregate lixiviates (hemp hurd) on the hydration kinetics of calcium sulfoaluminate (CSA) cement as a low-embodied-carbon alternative to ordinary Portland cement (OPC). The isothermal calorimeter showed that the hemp hurd lixiviate caused a greater delay in GU's hydration process than CSA's. At a 5% concentration, the main hydration peak for GU cement emerged after 91 h, whereas for CSA cement, it appeared much earlier, at 2.5 h. XRD and TGA analysis showed that after 12 h of hydration, hydration products such as calcium silicate hydrates (C-S-H) and portlandite (CH) were not able to form on GU cement, indicating low hydration of silicate products. Moreover, at 5% concentration, the carbonation of ettringite was observed in CSA cement. The compressive strength values obtained from the mixes containing hemp hurd lixiviate consistently showed lower values compared to the reference samples prepared with distilled water. Furthermore, the CSA samples demonstrated superior compressive strength when compared to the GU samples. After 28 days of hydration, the compressive strength values for CSA cement were 36.7%, 63.5% and 71% higher than GU cement at a concentration of 0.5%, 2% and 5% hemp hurd lixiviate, respectively.

Comparative Life Cycle Assessment of Different Portland Cement Types in South Africa

Cement has long been recognized as an energy- and emission-intensive construction material. Cement production has recently experienced significant growth despite its high energy consumption, resource usage, and carbon emissions. This study aims to assess and compare the life cycle assessment (LCA) of traditional Portland cement (CEM I) to those of three blended cement types (CEM II/B-L, CEM II/B-V, and CEM III/A), which assume mature technologies for reducing carbon emissions in South Africa, using LCA in compliance with ISO/TS 14071 and 14072. As its scope, the study employs the “cradle to gate” method, which considers the raw materials, fuel usage, electricity, transportation, and clinkering stages, using 1 kg of cement as the functional unit. The LCA analyses were performed using SimaPro 9.1.1.1 software developed by PRé Consultants, Amersfoort, Netherlands and impact assessments were conducted using the ReCiPe 2016 v1.04 midpoint method in order to compare all 18 impact categories of 1 kg of cement for each cement type. The assessment results show reductions in all impact categories, ranging from 7% in ozone depletion and ionizing radiation (CEM II/B-L) to a 41% reduction in mineral resource scarcity (CEM III/A). The impacts of global warming were reduced by 14% in the case of CEM II/B-L, 29% in the case of CEM II/B-V and 35% in the case of CEM III/A. The clinkering process was identified as the primary cause of atmospheric impacts, while resource depletion impacts were attributed to raw materials, fuels, and electricity processes, and toxicity impacts were primarily caused by raw materials. Alternative materials, like fly ash and ground granulated blast furnace slag (GGBFS), can significantly help to reduce environmental impacts and resource consumption in the cement industry.

Carbonation of supersulfated cement concrete after 8 years of natural exposure

Supersulfated cement (SSC) has garnered attention as a potential lower-carbon alternative to traditional Portland cement, but its carbonation resistance has raised concerns about its wider implementation. This study aims to evaluate the carbonation behavior of SSC concrete after 8 years of natural exposure, examining the carbonation depths, changes in hydration products, and microstructures of SSC concrete with different water-to-cement ratios. The results showed that the carbonation rate of SSC concrete with a C30 grade was 1.02 mm/year, while the carbonation rate of SSC concrete with a C50 grade was 0.54 mm/year. During the exposure process, ettringite in the SSC concrete was found to be the first hydration product to carbonate, leading to a dense pore structure. However, once C–S–H gels began to carbonate, the pore structure rapidly coarsened, resulting in a significant increase in pore network connectivity. Carbonation in SSC concrete generated calcium carbonate with aragonite as the dominant polymorph due to the extensive carbonation of ettringite. The results of this study on the carbonation behavior of SSC concrete under natural conditions can serve as a reference for validating the results of accelerated carbonation tests and provide a foundation for developing a carbonation model for SSC concrete under complex environmental conditions.

Predicting the mechanical strength of coal pond ash based geopolymer concrete using linear regression method

Geopolymer concrete (GPC) is an innovative alternate material that can replace traditional Portland cement concrete. Generally, GPC requires heat or steam chamber during curing for optimal geopolymerization response on concrete specimens, which is tedious and a time-consuming process. Modified GPC is introduced to overcome these limitations as well as to improve the characteristics of specimens. This study goal was to assess and examine the mechanical strength of GPC when mixed with slaked lime, ground granulated blast furnace slag (GGBS), and pond ash (PA) at various proportions. Slaked lime was added at a rate of 1%, 2%, 3%, 4%, 5%, and 6% by combined weight of PA and GGBS. Concrete specimens were casted and cured for 7, 28, 56, and 90 days at ambient environmental condition. Experimental test results showed that PA and GGBS based GPC significantly gained mechanical strength than conventional GPC at 7, 28, 56, and 90 days. The admixtures PA and GGBS not only increased the strength of GPC but also reduced the curing time. In addition, it was found that the improvement in properties was the result of densification of microstructures over curing time.

Modifying Water-Frost Resistance and Mechanical Properties of Lime Mortar Using Siliceous and Fluidised Bed Fly Combusted Ashes Activated with Cement.

The research focuses on pozzolanic additives, which are compatible with traditional lime mortars, and enable the modification of the rheological, physical and mechanical properties of tested composites. It was noted that lime mortars with fluidised bed fly ash require sand without impurities to avoid possible ettringite crystallisation. The work presents siliceous fly ash and fluidised bed combustion fly ash to modify the frost resistance and mechanical properties of traditional lime mortars with and without the addition of cement. The results show better effects using fluidised bed ash. Traditional Portland cement CEM I 42.5R was used to activate ash and increase the results. The possibility of a significant improvement of properties is indicated with a hybrid addition to the lime binder of 15-30% ash (siliceous or fluidised bed ash) and 15-30% cement. Changing the class and type of cement provides an additional opportunity to alter the properties of the composites. For architectural reasons relating to colour, the suitability of lighter fluidised bed ash instead of darker siliceous ash and of white Portland cement instead of the traditional grey cement can be used. The proposed mortars can be the basis for future modifications with admixtures and additives, e.g., metakaolin, polymers, fibres, slag, glass powder and impregnating agents.

Stabilization of Aeolian Sand for Pavement Subbase Applications Using Alkali-Activated Fly Ash and Slag

Using local materials to construct building elements as well as transport road facilities, including highways, intercity roads, and roads, in remote areas is a top topic of scholarly research all over the world. The main reason for that is the fact that these kinds of materials not only ease the intensity of material transportation but are also cost-efficient. In desert areas, aeolian sand is a commonly used local material and it has been investigated in unbound and cement-stabilized pavement base/subbase applications. However, the production of cement is associated with a high carbon footprint, leading this research to seek alternative low-carbon binders. This research investigated the strength properties and the carbon footprint of fly ash (FA) and a ground-granulated blast-furnace slag (S)-based geopolymer-stabilized aeolian sand. Setting time, compressive strength, California bearing ratio (CBR), and temperature shrinkage measurements of the stabilized aeolian sand were carried out in this research. The maximum strength of the stabilized aeolian sand was found at the optimal ratio of Si/Al ratio of 2.5 and Na/Al ratio of 1.0. The compressive strength increased as the geopolymer stabilizer content increased. A stabilizer content ranging between 8% and 20% is recommended in practice. The carbon footprint of the geopolymer-stabilized aeolian sand was lower than that of cement-stabilized aeolian sand. This tendency became more evident in the samples with higher strength, indicating the effectiveness of geopolymer as an alternative green soil stabilizer to traditional Portland cement.

Accelerated carbonation of one-part sodium carbonate-activated slag cements modified by calcined dolomite

One-part or ‘just add water’ alkali-activated material is one promising option of the clinker-free cementitious material being actively researched as the alternative to traditional Portland cements for lowering the energy consumption and CO2 emission involved in the clinker production. The one-part sodium carbonate (Na2CO3)-calcined dolomite (CD)-activated slag cements were developed in this work. The CD additions were effective in shortening the setting times and meanwhile enhancing the compressive strengths of the binders. The carbonation resistance was investigated under accelerated carbonation protocols at 3.0 ± 0.2% CO2. The CD additions slowed down the kinetics of carbonation. Although the binders still underwent the pore structure degradation, the reactive CaO and MgO supplied by CD promoted the formation of calcium hemi-carboaluminate and hydrotalcite-like phase, which had the layered double hydroxide structure with the anion exchange capacity for binding the ingressive CO32− ions. Therefore, the CD addition should be recognized as a novel approach for improving the carbonation resistance of such one-part Na2CO3-activated slag material.

Development of sustainable high performance geopolymer concrete and mortar using agricultural biomass—A strength performance and sustainability analysis

Geopolymer concrete is a sustainable substitute for traditional Portland cement concrete. In addition, rising carbon taxes on carbon emissions and energy-intensive materials like cement and lime, impacts the cost of industrial by-products due to their pozzolanic nature. This research evaluates the compressive strength and flexural strength of geopolymer concrete, and the compressive strength of geopolymer mortar. Geopolymer mortar data were used for the strength assessment employing an analytical approach, and geopolymer concrete data were utilized for the strength and sustainability performances. Using artificial neural networks (ANNs), multi-linear regression (MPR) analysis, and swarm-assisted linear regression, compressive strength models were created based on experimental datasets of geopolymer mortar mixes with variable precursors, alkali-activator percentages, Si/Al, and Na/Al ratios. The strength and sustainability performances of geopolymer concrete blends with various precursors were assessed by considering cost-efficiency, energy efficiency, and eco-efficiency. The work’s originality comes from enhancing sustainable high-performance concrete without overestimating or underestimating precursors. Extensive experimental work was done in the current study to determine the best mix of geopolymer concrete by varying silica fume, ground granulated blast furnace slag (GGBS), and rice husk ash (RHA). A scanning electron microscopic study was conducted to understand the geopolymer matrix’s microstructure further. A comprehensive discussion section is presented to explain the potential role of RHA. The replacement of conventional concrete in all its current uses may be made possible by this sustainable high-performance concrete utilizing RHA.

Experimental Study on Cemented Tailings Backfill Based on Microbially Induced Calcite Precipitation

The backfill mining method is an effective method to control ground pressure and prevent surface subsidence in the process of underground resources exploitation. Tailings backfill not only relieves the pressure of tailings reservoir but also protects the environment. However, traditional Portland cement as the cementing material results in groundwater pollution. In addition, the production process of Portland cement consumes a significant amount of mineral resources and causes air pollution. Therefore, a cementation method for tailings based on microbially induced calcite precipitation (MICP) is proposed in this paper. Tailings cementation by the MICP technology with facultative anaerobic bacteria (Castellaniella denitrificans) can overcome the problems of MICP technology based on urea hydrolysis of aerobic bacteria (Sporosarcina pasteurii), which cannot be applied in anoxic or anaerobic environment. In addition, in view of the small amount and poor uniformity of calcium carbonate precipitation in the specimens cemented by facultative anaerobic bacteria alone, a mixture of facultative anaerobic bacteria and aerobic bacteria was adopted for tailings cementation in this study. The results showed that, with increasing Castellaniella denitrificans concentration, the cementation effect improved. The tailings sand was cemented into a compact specimen when the OD600 of the bacterial solution was one and the uniaxial compressive strength could reach 987.93 kPa. Compared to cementation induced by a single strain, the amount of calcite precipitation induced by the mixed bacteria increased from 2.54% to 3.59%, the uniaxial compressive strength was enhanced by 29.9%, and the shear strength increased by 24.4%. This study indicates that MICP technology with facultative anaerobic bacteria has great potential in tailings cementation, and it can provide a solution to replace cement as the cementing material for tailings.

Valorization of limestone powder as an additive for fly ash geopolymer cement under the effect of the simulated tidal zone and seawater attack

Generally, buildings and constructions subjected to the harsh marine environment, especially tidal zone, are usually more susceptible to deterioration than others. Therefore, choosing the type of cement is important to limit this degradation. Limestone powder is widely used as a cementitious material in traditional Portland cement systems due to its availability and low cost. Unlike in the geopolymers, using limestone powder is still in its growth stage, especially in fly ash geopolymer cement. The recent article is the first attempt to enhance fly ash geopolymer cement with limestone powder aiming to limit the deterioration caused by seawater attack and the simulated tidal zone. For this reason, the fly ash was partially replaced with limestone powder at levels oscillating from 10 % to 60, by weight, with a stride of 10 %. After initial curing, the specimens were exposed to seawater attack and the simulated tidal zone for 3, 6 and 12 months. Other specimens were exposed to the air and tap water for the same periods for comparison purposes. Compared to the specimens cured in the air, the results disclosed that the specimens subjected to the simulated tidal zone showed the highest impairment ratios followed by those submerged in seawater, whilst the specimens submerged in tap water came in last place. The incorporation of limestone powder up to 20 % into fly ash geopolymer cement showed a positive effect in enhancing the compressive strength and limiting the deterioration caused by the harsh environment, whilst higher ratios than 20 % showed a negative effect.

Influence of pozzolans on plant oil‐sulfur polymer cements: More sustainable and chemically‐resistant alternatives to Portland cement

AbstractLow cost and high durability have made Portland cement the most widely‐used building material, but benefits are offset by environmental harm of cement production contributing 8–10% of total anthropogenic CO2 gas emissions. High sulfur‐content materials (HSMs) are an alternative that can perform the binding roles as cements with a smaller carbon footprint, and possibly superior chemical, physical, and mechanical properties. Inverse vulcanization of 90 wt% sulfur with 10 wt% canola oil or sunflower oil to yield CanS or SunS, respectively. Notably, these HSMs prepared at temperatures ≤180 °C compared to >1200 °C hours for Portland cement CanS was combined with 5 wt% fly ash (FA), silica fume (SF), ground granulated blast furnace slag (GGBFS), or metakaolin (MK) to give composites CanS‐FA, CanS‐SF, CanS‐GGBFS, and CanS‐MK, respectively. The analogous protocol with SunS likewise yielded SunS‐FA, SunS‐SF, SunS‐GGBFS, and SunS‐MK. Each of these HSMs exhibit high compressive mechanical strength, low water uptake values, and exceptional resistance to acid‐induced corrosion. All of the composites also exhibit superior compressive strength retention after exposure to acidic solutions, conditions under which Portland cement undergoes dissolution. The polymer cement‐pozzolan composites reported herein may thus serve as greener alternatives to traditional Portland cement in some applications.

Revolutionizing concrete: A study of geopolymer concrete with metakaolin and G.G.B.S. inclusion

With time, the infrastructure is growing rapidly, and concrete has become one of its main components. Due to the adverse effects of cement production on the surrounding environment, utilizing cement in concrete can be a challenging job. Geopolymer concrete is gaining rapid recognition as an inventive construction material, serving as a great substitute for traditional Portland cement concrete and effectively contributing to the reduction of cement usage. In this research, pozzolanic substances including Ground Granulated Blast Furnace Slag (G.G.B.S.), Metakaolin (M.K.) as a binding agent, and sodium silicate and sodium hydroxide as alkali activators were employed. The proportion of alkali to binder remained constant at 0.45 throughout the study. The samples were casted for different mixes and tested for compressive strength and sulphate resistance. The results of the study indicated that the mix prepared with 14 molarity of alkali activators shows the better performance as compared to other mixes.

Effects of Cationic Surfactant on Fresh and Hardened Properties of Cement-Based Mortar

The objective of this study is to analyze the effects of using surfactant (CTAB) and cellulose nanofibers (NFC) as an admixture in cement mortars. We examined composite properties as porosity, compression energy, thermal conductivity and hydration. The results showed that with the addition of 0.7% by weight of NFC per emulsion in the presence of a cationic surfactant (CTAB). The new material produced presented a dry porosity between 4.7% and 4.4%, compressive strength between 9.8 and 22.9 MPa, and thermal conductivity between 0.95 and 2.25 W·m−1·K−1. Thus we show better mechanical and thermal performance than that traditional Portland cement mortar with a density similar. In addition, the mortar made by emulsion of ordinary portland cement, cellulose nanofiber and organophilic clay (OC) treated with cetyltrimethylammonium bromide (CTAB) obtained has good resistance under high temperature and water, as well as excellent thermal insulation performance under high temperature and humidity conditions. This study verified that the presence of NFC promotes hydration, leading to the production of more calcium silicate and portlandite gel.

Lightweight porous geopolymers from waste red brick precursor and synthetic foaming admixture

Geopolymers are associated with a high potential to replace traditional Portland cement. Up to now, research has been ongoing on alternative precursors with wide availability, low cost, and low environmental impact. Attention is paid to ashes, industrial by-products, and construction and demolition waste. Sophisticated materials with high porosity and improved physical or mechanical properties are developed to enhance the application of geopolymers. In this paper, the waste red brick is used as a precursor to produce highly porous geopolymers. Here, porous geopolymers on waste brick precursor and synthetic foaming agent were developed for the first time. Red waste brick was ground to powder particles and activated with NaOH solution. A porous structure was obtained by a pre-foaming technique where geopolymer slurry was mixed in the foams. Physical and mechanical properties were evaluated depending on mixture composition and foaming agent content. Porous geopolymers with densities from 240 to 1200 kg/m3 were obtained. The pore structure of obtained materials was characterized. Reduced density and characteristics of red clay precursor summarised in low compressive strength which was from 0.04 to 0.4 MPa.

Recent Advances in Alternative Cementitious Materials for Nuclear Waste Immobilization: A Review

Since the emergence of the problem of nuclear waste conditioning, cementation has become an important and developing part of the waste management system, owing to its simplicity and versatility. The continued development of the cementation technique is driven by the improvement and expansion of cementitious materials that are suitable and efficient for nuclear waste solidification. Advances in cement theory and technology have significantly impacted improvements in nuclear waste cementation technology, the quality of fresh and hardened waste forms, waste loading rates, and the reliability and sustainability of the nuclear industry. Modern mineral matrices for nuclear waste immobilization are a broad class of materials with diverse chemical–mineralogical compositions, high encapsulation capacities, and technological and engineering performance. These matrices include not only traditional Portland cement, but also non-Portland clinker inorganic binders. This review focuses on recent trends and achievements in the development of calcium aluminate, calcium sulfoaluminate, phosphate, magnesium silicate, and alkali-activated cements as cementitious matrices for nuclear waste stabilization/solidification.

Comparison between MICP-Based Bio-Cementation Versus Traditional Portland Cementation for Oil-Contaminated Soil Stabilisation

In recent years, oil spills and leakages have often occurred during oil exploration, transportation, handling, usage, and processing, causing serious global environmental problems. Microbially-induced carbonate precipitation (MICP) is an emerging green, environmentally friendly, and sustainable technology that has proven to be a promising alternative for soil stabilisation. This paper provides a comparison between the mechanical performance of oil-polluted sand treated with biocement and traditional Portland cement. A series of laboratory tests, including permeability, unconfined compressive strength (UCS), and triaxial consolidated undrained (CU) tests, was conducted. Even though oil contamination deteriorates the bonding strength of treated soil for both biocement and Portland cement soils, the biocement-treated oil-contaminated sand was found to achieve higher strength (up to four times) than cement-treated soil in the presence of similar content of cementing agent. After eight treatment cycles, the UCS value of oil-contaminated sand treated with biocement reached 1 MPa, demonstrating a high potential for oil-contaminated soil stabilisation in regions of oil spills and leakages.