Calcium Carbonate Cement Research Articles

Impact of clay reactivity on the hydration of calcined clay limestone cements

The substitution of Portland cement clinker with a combination of calcium carbonate and calcined clay is a promising binder concept to lower the CO2 footprint of the cement industry due to the synergetic effect of both materials which form carbo-aluminate hydrates. In this study, the reactivity of several calcined clays was tested using the R3 test and mortar strength testing in different combinations with calcium carbonate and Portland cement. A multiple regression analysis revealed that the reactivity in the R3 test depends mainly on the amorphous Al2O3 and to a minor extent on the grain size and the MgO content. It was found that the most reactive calcined clay according to the R3 test led to no significant increase in compressive strength between 7 and 28 days. This clay also shows a slightly lower overall strength after 28 days than a calcined clay that was rated “medium reactive” according to the R3 test. The most reactive calcined clay was further investigated in a hydration study using X-ray diffraction. Based on this, a thermodynamic model was built and revealed that only a comparatively small percentage of the calcined clay reacted after 28 days.

Microstructure development of calcium carbonate cement through polymorphic transformations

This study presents the mechanical properties and polymorphic transformation of pastes made with calcium carbonate cement, where vaterite was the main component. Both laboratory (compression tests, XRD, & SEM) and synchrotron-based techniques (transmission X-ray microscopy and microtomography) were used in the characterization of the pastes. Mechanical properties were developed by controlling the polymorphic transformation of vaterite. When converting to aragonite, calcium carbonate cement exhibited three times greater strength development compared to its conversion to calcite at a water-to-cement ratio of 0.4, which resulted in 42 % porosity. During the conversion to aragonite, the calcium carbonate cement paste develops an interpenetrating matrix of aragonite needles that enhance strength development through interlocking at a low paste bulk density of 1.6 g/cm3. Together the environmental and mechanical properties of calcium carbonate cement suggest its potential as a greener building material compared to traditional Portland cement.

Field implementation to resist coastal erosion of sandy slope by eco-friendly methods

Coastal erosion is a global issue that not only compresses land space but also undermines offshore structures. In this study, two eco-friendly technologies (microbially and enzyme induced calcium carbonate precipitation) were implemented at a sandy slope field site to enhance erosion resistance. Improvement of the treated sandy slope against erosion was assessed by penetration resistance, calcium carbonate content, cone penetration testing (CPT) results, terrain data and microscopic morphology. Results indicated that the penetration resistance and calcium carbonate content of treated slopes increased first and then decreased over time because of the gradual formation of calcium carbonate and the erosion caused by the marine environment. Calcium carbonate content and penetration resistance presents an obvious linear relationship. The existence of the superficial cemented crust layer increased the water retention capacity of the sand in the atmosphere region. The calcium carbonate content and CPT results in the tidal region shows the characteristics of layered cement. The spherical calcium carbonate cementation improves the roughness and integrity of the terrain, enhances the particle size of the sand, gradually changing the topography from pre-treatment dynamic erosion to depositional patterns. The treated slope still maintained a certain penetration resistance and calcium carbonate content for 60 days until being eroded by the wind in the atmosphere region. However, the effective protection duration in the tidal zone which encounters wind, wave, tide and reflow was about 24 days, and would thus need to be reinforced periodically over time to obtain long-term protection.

Experimental study on permeability and strength characteristics of MICP-treated calcareous sand

Calcareous sand is the main fill material for island reclamation projects, but untreated calcareous sand might not be used as a reclamation fill due to its poor mechanical properties. Microbial induced calcite precipitation (MICP) was directly used to consolidate calcareous sands. One-dimensional sand column tests were conducted to identify the optimized solutions and to investigate the effects of cement solution concentration, relative density, and consolidation frequencies on the permeability and mechanical properties of MICP-treated calcareous sands. Finally, three-dimensional model tests were carried out to investigate the effective consolidation range of microbially treated calcareous sands. The results show that the MICP-treated calcareous sand shows a reduction in the permeability of the sample, while the calcium carbonate cementation and its filling effect improves the mechanical properties of the soil. The one-dimentional test results show that the effective values for cement solution concentration, relative density, and consolidation frequencies range from 0.5 mol/L to 1.5 mol/L, 30%–70%, and 5–15 times. The consolidation frequencies have the greatest influence on the permeability and strength properties of the treated calcareous sand. A quadratic polynomial regression model for permeability and strength was established through response surface analysis, and the regression model proved to be highly accurate and reliable through testing. In three-dimentional tests, the consolidation range tends to move downwards in a trapezoidal shape, showing a "big bottom and small top" pattern, with a consolidation range of approximately 34 times the diameter of the pipe. This study serves as a reference for selecting consolidation parameters for subsequent tests and applications of MICP-treated calcareous sands.

Phosphorylated chitosan as a hydrosoluble additive for bioactive calcium carbonate cements: Elaboration, setting mechanism, and handling properties

Chitosan is extensively used in the biomedical field owing to its biocompatibility and degradability. However, its limited solubility hinders its use as an effective additive in bone mineral cements. This study aimed to synthesize water-soluble phosphorylated chitosan and introduce it in calcium carbonate cement in view to control the composition, in vitro bioactivity, and physicochemical properties of the cement for bone repair. NMR spectroscopy results showed that chitosan was selectively functionalized (Cs–P) with phosphate groups mainly grafted at the C6 position on the chitosan backbone. For the first time, phosphorylated chitosan was associated with calcium carbonate cement; it was dissolved in a Na2CO3 solution (liquid phase of the cement) used as a setting accelerator. The quantitative XRD analysis at different time points revealed that the dissolution-recrystallization mechanism involved in the paste setting and hardening was different than for the reference cement: composite cement including 2.5 wt% Cs–P was mainly composed of vaterite (74 wt%) stabilized by Cs–P and some magnesian calcite (26 wt%). We pointed out the pivotal role of the calcium-binding ability of Cs–P phosphate groups and also of magnesium in controlling the cement setting mechanism and properties and its evolution in SBF. Interestingly, this composite cement also exhibited good physicochemical and handling properties: short initial (17 min) and final (28 min) setting times, high injectability (95%), enhanced anti-washout resistance of the paste, and a compressive strength compatible with implantation in non-load bearing bone defects. The in vitro evolution of the composite cement in SBF solution revealed some apatite formation on the cement surface and a high resorption rate (>20% at 28 days) owing to the solubility of the vaterite polymorph, making this composite cement a promising resorbable and bioactive ceramic able to be implanted through a minimally invasive technique.

Strength and uniformity of EICP-treated sand under multi-factor coupling effects

Enzyme-induced carbonate precipitation (EICP) is an environment-friendly method for improving soil mechanical properties. The extraction and application of plant crude urease reduces the treatment cost. However, in terms of the efficiency of calcium carbonate production and cementation, crude urease is considered inferior to pure urease or urease bacteria. In this paper, urease extracted from soybean was used to explore the effects of urease activity, treatment method, number of treatments (NTs), injection rate, and curing time on the unconfined compressive strength and calcium carbonate distribution characteristics of EICP-treated sand. The results showed that, compared with the pre-mixing method and the two-phase method, the one-phase method produced higher strength and a more uniform distribution of calcium carbonate. The cementation efficiency decreased with the increase of urease activity. The high-rate injection can improve the treatment effect of high-activity urease. Under the same cementation level, high strength and calcium carbonate cementation efficiency can be achieved by one-phase-low-activity EICP treatment. Data Availability StatementAll data, models, and code generated or used during the study appear in the submitted article.

Evaluation of the bonding properties between low-value plastic fibers treated with microbially-induced calcium carbonate precipitation and cement mortar

Plastic fiber reinforced cementitious materials offer the potential to increase the reusability of plastic waste and create lower-CO2 cementitious composites. However, the bonding properties of many plastic types with ordinary Portland cement (OPC) are largely unknown. This work employs single fiber pullout (SFPO) tests to quantify the interfacial bonding properties of polyvinyl chloride, low-density polyethylene, polypropylene, polystyrene, and acrylonitrile butadiene styrene embedded in OPC mortar. The interfacial bonding properties were compared for fibers either treated with microbially-induced calcium carbonate precipitation (MICP) or left untreated. SFPO tests revealed that plastic type had a large influence over bonding properties. Specifically, the fiber surface energy, as estimated from water contact angle measurements, was found to be the driving factor of bond strength. ABS had the highest surface energy and demonstrated the strongest bonding out of all plastic types studied. However, MICP treatment of fibers did not increase the interfacial bond strength for any of the plastics studied. The thick and inconsistent coverage of biomineral over the fiber surface from MICP is likely attributed to preventing an increase in bond strength. These results contribute to the design and application of plastic-reinforced mortars by comparing bonding properties for a range of typically low-value, unrecycled plastic types.

DESCRIBING DIFFICULT SHELL-HASH ASSEMBLAGES FROM THE LOWER CAMBRIAN SOLTANIEH FORMATION, ALBORZ MOUNTAINS, NORTHERN IRAN

ABSTRACTThe fossil record spanning the latest Ediacaran and earliest Cambrian is characterized by the proliferation of small, mineralized organisms that comprise the well-known and abundant deposits of small shelly fauna. Many of these fossils are tubular or conical forms with simple morphologies, and thus present difficulties in both taxonomic and phylogenetic interpretation. This study investigates a community of poorly preserved shelly tubicolous organisms in two fossiliferous slabs from the Soltanieh Formation, northern Iran. Analysis of the taphonomy of this fossil assemblage using thin-section petrography, scanning electron microscopy, and energy dispersive X-ray spectroscopy, suggests a two-part preservational pathway involving phosphatic replacement of the shell wall and separate, diagenetically later infillings of void space with either phosphatic or calcium carbonate cements. In parallel with the taphonomic study and given the difficulty in assigning the observed fossils taxonomically, morphometrics of the shelly organisms were also explored. Biometric measurements were collected from high-resolution photomosaic images of the slab-surface fossils, as well as from a three-dimensional volume of the interior of one of the slabs generated via X-ray tomographic microscopy. Statistical analysis of these measurements revealed a separation of the fossils into two morphologically distinct groups of conical and tubular forms, which we characterize respectively as ‘conomorphs' and ‘tubomorphs'. Based on previous studies of fossils from the Soltanieh Fm., we can offer tentative generic-level assignment to Anabarites and Cambrotubulus to at least some of the fossils present, though these are dependent on views in thin section rather than morphometric distinction. Cumulatively, we provide a conservative, taxonomy-free approach for detailing the morphology and preservation of poorly preserved fossils from the Ediacaran–Cambrian transition.

Compressive Strength of MICP-Treated Silica Sand with Different Particle Morphologies and Gradings

Microbially-induced calcium carbonate precipitation (MICP) can enhance the stiffness and bulk strength of sand aggregates via calcium carbonate cementation. This study explores the mechanical strength of silica sand aggregates with different particle morphologies and sizes following MICP treatment. Specifically, unconfined uniaxial compressive strength (UCS) of MICP-treated spherical, near-spherical, and angular aggregates are measured for four separate size fractions (18–25, 25–40, 40–60, and 60–80 mesh). Scanning electron microscope (SEM) imaging is performed on post-treatment samples to investigate the difference in cementation morphology and failure mechanisms. The experimental results indicate: (1) given identical cycles of MICP treatment, the UCS of treated spherical and near-spherical sands peaks at 25–40 mesh particle size, while the treated angular sands show increasing UCS with decreasing particle size; (2) spherical sands have the highest calcium carbonate (CaCO3) content given identical MICP cycles; and (3) higher post-treatment CaCO3 content does not correlate to higher UCS—implying that the distribution and morphology of CaCO3 precipitation exert crucial control. SEM analysis shows that CaCO3 fully encapsulates spherical sand particles uniformly, forming point contact bonds. In contrast, CaCO3 precipitations show a patchy distribution on near-spherical and angular sand grain surfaces. Unlike treated spherical sands, treated near-spherical sands feature a mixture of point and planar contact bonds while treated angular sands feature predominantly planar contact bonds. Planar contact bonds provide a larger effective cementation area between sand particles and thus result in higher bonding strength. The particle morphology and resultant inter-particle bonding morphology help reconcile higher ensemble UCS with lower CaCO3 content of treated angular sands.

Biocementation mediated by native microbes from Brahmaputra riverbank for mitigation of soil erodibility

Riverbank erosion is a global problem with significant socio-economic impacts. Microbially induced calcite precipitation (MICP) has recently emerged as a promising technology for improving the mechanical properties of soils. The present study investigates the potential of selectively enriched native calcifying bacterial community and its supplementation into the riverbank soil of the Brahmaputra river for reducing the erodibility of the soil. The ureolytic and calcium carbonate cementation abilities of the enriched cultures were investigated with reference to the standard calcifying culture of Sporosarcina pasteurii (ATCC 11859). 16S rRNA analysis revealed Firmicutes to be the most predominant calcifying class with Sporosarcina pasteurii and Pseudogracilibacillus auburnensis as the prevalent strains. The morphological and mineralogical characterization of carbonate crystals confirmed the calcite precipitation potential of these communities. The erodibility of soil treated with native calcifying communities was examined via needle penetration and lab-scale hydraulic flume test. We found a substantial reduction in soil erosion in the biocemented sample with a calcite content of 7.3% and needle penetration index of 16 N/mm. We report the cementation potential of biostimulated ureolytic cultures for minimum intervention to riparian biodiversity for an environmentally conscious alternative to current erosion mitigation practices.

Calcium Carbonate Cement: A Carbon Capture, Utilization, and Storage (CCUS) Technique.

A novel calcium carbonate cement system that mimics the naturally occurring mineralization process of carbon dioxide to biogenic or geologic calcium carbonate deposits was developed utilizing carbon dioxide-containing flue gas and high-calcium industrial solid waste as raw materials. The calcium carbonate cement reaction is based on the polymorphic transformation from metastable vaterite to aragonite and can achieve >40 MPa compressive strength. Due to its unique properties, the calcium carbonate cement is well suited for building materials applications with controlled factory manufacturing processes that can take advantage of its rapid curing at elevated temperatures and lower density for competitive advantages. Examples of suitable applications are lightweight fiber cement board and aerated concrete. The new cement system described is an environmentally sustainable alternative cement that can be carbon negative, meaning more carbon dioxide is captured during its manufacture than is emitted.

The role of bacterial urease activity on the uniformity of carbonate precipitation profiles of bio-treated coarse sand specimens

Protocols for microbially induced carbonate precipitation (MICP) have been extensively studied in the literature to optimise the process with regard to the amount of injected chemicals, the ratio of urea to calcium chloride, the method of injection and injection intervals, and the population of the bacteria, usually using fine- to medium-grained poorly graded sands. This study assesses the effect of varying urease activities, which have not been studied systematically, and population densities of the bacteria on the uniformity of cementation in very coarse sands (considered poor candidates for treatment). A procedure for producing bacteria with the desired urease activities was developed and qPCR tests were conducted to measure the counts of the RNA of the Ure-C genes. Sand biocementaton experiments followed, showing that slower rates of MICP reactions promote more effective and uniform cementation. Lowering urease activity, in particular, results in progressively more uniformly cemented samples and it is proven to be effective enough when its value is less than 10 mmol/L/h. The work presented highlights the importance of urease activity in controlling the quality and quantity of calcium carbonate cements.

Practical approaches to study microbially induced calcite precipitation at the field scale

Microbially induced calcite precipitation (MICP) is a new and sustainable technology which utilizes biochemical processes to create barriers by calcium carbonate cementation; therefore, this technology has a potential to be used for sealing leakage zones in geological formations. The complexity of current MICP models and present computer power limit the size of numerical simulations. We describe a mathematical model for MICP suitable for field-scale studies. The main mechanisms in the conceptual model are as follow: suspended microbes attach themselves to the pore walls to form biofilm, growth solution is added to stimulate the biofilm development, the biofilm uses cementation solution for production of calcite, and the calcite reduces the pore space which in turn decreases the rock permeability. We apply the model to study the MICP technology in two sets of reservoir properties including a well-established field-scale benchmark system for CO2 leakage. A two-phase flow model for CO2 and water is used to assess the leakage prior to and with MICP treatment. Based on the numerical results, this study confirms the potential for this technology to seal leakage paths in reservoir-caprock systems.

Biocementation of soft soil by carbonate precipitate and polymeric saccharide secretion

This study utilised native denitrifiers of cattle manure to oxidise its organic matter and induce calcium carbonate cementation in a synthetic soft soil. The soft soil is prepared by remoulding a 50% kaolinite + 50% sand mix with ultra-pure water at 21% water content. The prepared specimen is classified as soft soil based on its low unconfined compression strength of 16 kPa. Extraneous calcium nitrate provides nitrate ions (electron acceptors) for the metabolism of denitrifying bacteria and calcium (Ca2+) ions for calcium carbonate formation. The facultative anaerobe community peaks and declines between 7 and 14 days. A small addition of magnesium oxide balances the pH reduction caused by acetic acid formation during microbial degradation of cattle manure. Acetic acid serves as a carbon substrate for the metabolic activities of denitrifying bacteria. The CO2 (gas) released during the metabolic activities of bacteria dissolves in water and forms bicarbonate ions. The anion combines with calcium ions in the alkaline environment to form calcium carbonate cement. In addition, the native extracellular polysaccharide (EPS)-secreting bacteria in cattle manure facilitate EPS bonding of soil aggregates. Soil structure, interfacial frictional resistance mobilised by cattle manure fibres, EPS bonding and calcium carbonate cementation enhance the compression strength of the stabilised specimen by 720%.

Mechanisms of Phase Transformation and Creating Mechanical Strength in a Sustainable Calcium Carbonate Cement.

Calcium carbonate cements have been synthesized by mixing amorphous calcium carbonate and vaterite powders with water to form a cement paste and study how mechanical strength is created during the setting reaction. In-situ X-ray diffraction (XRD) was used to monitor the transformation of amorphous calcium carbonate (ACC) and vaterite phases into calcite and a rotational rheometer was used to monitor the strength evolution. There are two characteristic timescales of the strengthening of the cement paste. The short timescale of the order 1 h is controlled by smoothening of the vaterite grains, allowing closer and therefore adhesive contacts between the grains. The long timescale of the order 10–50 h is controlled by the phase transformation of vaterite into calcite. This transformation is, unlike in previous studies using stirred reactors, found to be mainly controlled by diffusion in the liquid phase. The evolution of shear strength with solid volume fraction is best explained by a fractal model of the paste structure.

Application of Nanolimes for the Consolidation of Limestone from the Medieval Bishop's Palace, Lincoln, UK

Nanolimes are the first nanomaterials used in heritage conservation for natural stone consolidation. Thanks to their size, they show good penetration depth into substrates, high reactivity resulting in a faster carbonation process, and the ability to bridge cracks through the formation of a network of calcium carbonate cement. Two commercial nanolimes, CaLoSiL (IBZ Salzchemie) and Nanorestore (CSGI) and a dispersion of Ca(OH)2 nanoparticles, synthesized by an anionic exchange process, were applied to fresh and naturally weathered limestone specimens, previously removed from the medieval Bishop's Palace in Lincoln, UK. A protocol of non-destructive tests was defined to study the treatment effectiveness, both in the laboratory and on-site. The two commercial nanolimes exhibit a low penetration depth, accumulating on the surface and creating a white coating, and lead to only a small increase in surface hardness. On the contrary, the laboratory-synthesized consolidant was able to effect a good superficial consolidation, without affecting the water absorption and aesthetic properties of the specimens. These results, together with those obtained from the application and monitoring of the consolidants on-site, will be crucial for the planning of interventive conservation at the Bishop’s Palace.

Discussion on the Review and Outlook of Microbial Geotechnical Mineralization Technology

Microbially Induced Calcite Precipitation (MICP) has grown up to be a hot topic in geotechnical engineering. MICP is a technology that controls and utilizes microbial reactions to produce calcium carbonate cement. It can be used to solve problems in geotechnical engineering, such as improving rock and soil strength, reducing permeability, treating the polluted soil. Microbial mineralization involves a series of biochemical reactions, and the curing process is of particular importance. Therefore, the curing effect of MICP is restricted and impacted by many factors. Built on the factors of microbial mineralized calcium carbonate reaction and microbial mineralization, the principles of urea hydrolysis, denitrification and sulfur reduction were summarized. The effects of air conditions, environmental factors, fiber addition amount, soil water content, and treatment solution concentration on microbial mineralization technology were analyzed. The conclusion is as follows: in the aerated state, the calcium carbonate content is the highest; the low urease concentration, the natural climatic temperature (the best in summer), the pH value between 7-9 produces the most calcium carbonate and the compressive strength is the largest; When soil fiber content is 3%-5%, MICP technology works best; the low concentration treatment liquid is more suitable for the MICP technology; the microbial mineralization technology is suitable for the sand, but it can also produce good effects for other complex soil.

Microbial induced calcium carbonate precipitation in coal ash

The long-term storage of coal ash in impoundments can lead to concerns of structural stability as well as trace element migration to local surface water and groundwater sources. Microbial induced calcium carbonate precipitation (MICP) offers a potential approach for minimising leachability of heavy metal trace elements from coal ash by calcium carbonate cementation. In this study, a protocol for MICP treatment of coal ash has been experimentally developed. The MICP treatment is applied to three coal ashes from different power plants, and their response to the developed treatment protocol is assessed. Possible factors affecting the MICP treatment of coal ash are discussed in terms of efficacey and inhibition of the stabilisation process. For this purpose, several approaches such as shear wave velocity, electrical conductivity, pH measurement, acid washing, scanning electron microscopy, energy dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy were implemented. The results indicated that carbon/carbide content of the fly ash material has an important role in the efficacey of the MICP treatment process. The most likely explanation is carbon/carbide aids in the nucleation of calcium carbonate precipitation.

MICROBIAL INDUCED SLOPE SURFACE STABILIZATION USING INDUSTRIAL-GRADE CHEMICALS: A PRELIMINARY LABORATORY STUDY

One of the promising soil improvement techniques that have recently gained increased attention in Geotechnical and Civil Engineering is microbial induced carbonate precipitation (MICP). The MICP is mediated by ureolytic bacteria through a chain of biochemical reactions which lead to the formation of calcium carbonate cement in soil matrix and persuades the substantial bonds between the soil particles. The study presented herein focuses on surficial stabilization of slope soil (Hokkaido, Japan) by mediating industrial-grade chemicals through two different scales of preliminary laboratory investigations: small-scale columns and bench-scale slopes. Locally isolated Psychrobacillus sp. was cultivated in both industrial-grade media (beer yeast) and laboratory-grade media (NH4-YE: tris-buffer, ammonium sulfate and yeast extract), and the urease activities were compared. The results showed that the cultivation of bacteria in beer yeast resulted in higher urease activity (0.9 U/mL) compared to that in conventional laboratory media (0.4 U/mL). Also, UCS of the specimen treated using industrial-grade chemicals (urea fertilizer, beer yeast and snow melting reagent) was about two times higher than the specimen treated using conventional laboratory-grade chemicals (urea, CaCl2 and nutrient broth). The benchtop-scale test revealed that the highest surface strength (UCS of 1.02 MPa) was achieved while treating the soil by 0.5 M cementation solution at 30oC. Sets of colorimeter measurements were undertaken on treated slope models to compare precipitation profile at different locations. These findings suggest that industrial-grade chemicals can contribute as potential candidates in MICP applications from the perspective of cost reduction.

Setting behavior and bioactivity assessment of calcium carbonate cements

AbstractCalcium carbonate cements have emerged in the last few years as an attractive candidate for biomedical applications. They can be easily prepared by mixing water with two metastable calcium carbonate phases––amorphous calcium carbonate (ACC) and vaterite––which (re)crystallize into calcite during setting reaction. The transformation kinetics (and therefore the final surface cement composition) strongly depends on the initial mixture design and is controlled by the dissolution of ACC, whereas calcite nucleation typically controls their recrystallization in fluid batch experiments. Novel compositions are presented in this paper by incorporating organic molecules as a proxy to test their capability to carry on other biomolecules like proteins or antibiotics. The hardened samples are microporous and show excellent bioactivity rates, although their mechanical properties still remain poor. However, this would not be a handicap for in‐vivo applications such as bone filling, especially in low mechanical stress locations.