Formation Of Calcium Hydroxide Research Articles

Characterization of self-healing in cement-based materials with a low water-to-cement ratio during subsequent hydration

This study explores the role of subsequent hydration in healing cracks in cement-based materials, focusing on a water-cement ratio of 0.20 and aging up to 1260 days. A novel bond strength testing method and backscattered electron imaging (BSE) analyzed the relationship between bond strength and unhydrated cement. Techniques like X-ray diffraction (XRD), scanning electron microscopy (SEM), and mercury intrusion porosimetry (MIP) helped investigate crystal phase content and microstructural changes. Key findings reveal that subsequent hydration primarily produces calcium hydroxide (CH), calcium carbonate (CaCO3), and C–S–H gel. Bond strength notably increased to 36.08 % at 394 days, with a significant reduction in C3S and C2S phases and increases in CH and CaCO3. The calcium-silicon ratio varied across hydration products, with external products containing the highest ratio. The study demonstrates the transformation of C–S–H gel from low to high density and highlights the cohesive structure formation of CH and C–S–H gel, crucial for crack healing. Porosity showed an initial decrease followed by an increase, peaking at 54.14 % above the initial value. These findings underscore the importance of controlling unhydrated cement content for optimizing self-healing in cement-based materials.

Effect of 2-acrylamide-2-methylpropane sulfonic acid on the early strength enhancement of calcium silicate hydrate seed

Nanomaterials are becoming widely used in cement to enhance the properties of cement-based materials. Artificially synthesized nano-C-S-H serves as a nucleation site for the hydration product C–S–H gel, facilitating its formation. This is deemed as an early strength agent to effectively promote cement hydration. Introducing comb-like polycarboxylate ether (PCE) during the synthesis of C–S–H can effectively reduce the size of C–S–H, resulting in better early strength effects. In this study, the acid-ether ratio of PCE is set at 6:1, and 2-acrylamido-2-methylpropane sulfonic acid (AMPS) substitutes acrylic acid (AA) at varying molar ratios to obtain modified PCE. Calcium silicate hydrate seed-polycarboxylate ether (C-S-Hs-PCE) is synthesized using co-precipitation technique. This study investigated impacts of AMPS on the particle size of C-S-Hs-PCE and the early strength of cement-based materials using dynamic light scattering analysis, total organic carbon analyzer, X-ray diffraction analysis, low-field nuclear magnetic resonance, scanning electronic microscopy, isothermal calorimeter, and compressive strength testing. The results show that the C-S-Hs-PCE, synthesized at an AMPS to AA molar ratio of 5:95, turns out to possess a reduced particle size compared to use of PCE without AMPS. This is pivotal in promoting the hydration of the silicate phase and the formation of calcium hydroxide and C–S–H gel in the paste, and thereby reducing the total porosity while improving the early mechanical strength of the mortar, especially within first 24 h.

Impact of triethanolamine on the hydration of Portland cement in the presence of high pozzolanic activity supplementary cementitious materials

Triethanolamine (TEA) is a widely employed cement accelerator that has been demonstrated to have a favorable impact on the early strength of cement at moderate dosing levels, while having a slight or negative impact on the later strength. This study systematically investigates the hydration pattern and strength development of Portland cement systems with the incorporation of fly ash microspheres and silica fume at a dosage of 0.02 % triethanolamine. The results proved that the addition of TEA had a positive impact on the early strength of the pure Portland cement system, while the later strength was reduced. However, the presence of high pozzolanic activity supplementary cementitious materials (SCMs) altered this reduction and even reversed it, resulting in an increase in strength. Specifically, TEA inhibits the crystallization nucleation growth of hydration products through complexation, resulting in the inhibition of the hydration of silicate minerals. The nucleation effect of silica fume, however, eliminates this inhibition and promotes the hydration of all minerals. Moreover, the presence of SCMs leads to the formation of more amorphous calcium hydroxide (CH) due to the demand of pozzolanic reaction, and the addition of TEA promotes the formation of amorphous CH, effectively lowering the reaction threshold of the pozzolanic reaction and facilitating it. The results confirm that the interaction of the complexation reaction of TEA with the pozzolanic reaction provides a beneficial complement to cement strength development.

Developing Innovative Cement Composites Containing Vine Shoot Waste and Superplasticizers.

The expansion of the construction industry requires large quantities of construction materials; therefore, the utilization of alternative raw materials that reduce the environmental impact and enhance the quality of the construction materials has received increasing interest. The comparative performance of 1% Dynamon SR3 or Dynamon SR41 superplasticizers on the properties of cement paste with 1 wt.% vine shoot waste addition (VSW) was investigated after 28 days using Fourier-transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX), and solid-state 27Al and 29Si nuclear magnetic resonance (NMR) spectroscopy. VSW does not delay the formation of calcium hydroxide and C-S-H and a slight decrease of the -OH band in samples containing superplasticizers, suggesting that free lime is converted to carbonates. The highest degree of crystallinity was remarked for the samples with superplasticizers. The structure of the cement paste with VSW and superplasticizers was corroborated with mechanical properties, showing increased strength in using VSW and superplasticizers. The results showed that adding 1% VSW and superplasticizers does not change the performance of the cement paste but reduces the water-cement ratio. The combination of VSW and superplasticizers led to cement composite with improved structural and mechanical properties suitable for construction.

New insights into the nucleation of portlandite and the effects of polymeric additives

The crystallization of calcium hydroxide (Ca(OH)2, CH, portlandite) is a key process during the early stages of cement hydration. In the present work, we have revisited the formation of this mineral through nucleation and growth from supersaturated aqueous solutions, in the light of the currently emerging picture of multistage “non-classical” crystallization. To that end, we developed a titration-based assay, in which stock solutions of both relevant ions are added simultaneously into a reservoir, where supersaturation increases slowly at constant stoichiometry until nucleation occurs. This procedure allows both pre- and early post-nucleation phenomena to be analyzed quantitatively. Complementarily, the early stages of portlandite mineralization were probed by various advanced characterization techniques, including cryo-transmission electron microscopy (cryo-TEM), in-situ small-angle X-ray scattering (SAXS), pair distribution function (PDF) analysis of high-energy X-ray scattering (HEXS) data, and analytical ultracentrifugation (AUC). The experimental data show that the formation of calcium hydroxide starts with the association of ions into complexes and clusters, which subsequently coalesce to form amorphous nanoparticles – much like what has been observed in the case of calcium carbonate and other prominent minerals. Subsequently, these particles aggregate and build networks, which eventually transform into hexagonal Ca(OH)2 crystals. The presence of a soluble polycarboxylate – as a known inhibitor of portlandite crystallization – does not change the main characteristics of this multistep nucleation pathway, but it proved capable of significantly extending the lifetime of the amorphous intermediate phase and thus delaying the transition to the final crystalline phase. Our observations confirm the notion that “non-classical” crystallization is a much more common phenomenon than initially believed – and that, for minerals forming in aqueous environments, it may actually be the rule rather than the exception.

Experimental investigation on effects of polyaniline-modified-lignin on cement-based materials: Strength, hydration and dispersion

The application of lignin dispersants in cementitious materials has been limited due to its strong retarding effect on cement hydration. In this study, polyaniline modified lignin (PL) was prepared to be as a new lignin additive to increase the dispersion of cement system and maintain good mechanical properties of cementitious materials. This investigation systematically revealed that different contents of PL (0%, 0.5%, 1.0%, 2.0%) had various effects on the early hydration, the work performance and the microstructure of cement paste and mortar. Appropriate dosage of PL was beneficial to achieve better dispersion and improve the fluidity of cement system. The retarding effect on cement hydration was significantly reduced by PL, compared to unmodified lignin. When the content of PL was 0.5% and 1.0%, the mechanical properties of the mortar was maintained as well as mortar without PL. However, excessive content of PL (2.0%) decreased the flexural strength and compressive strength significantly. XRD and TG tests exhibited that no new hydration products were generated and the formation of calcium hydroxide was inhibited after the addition of PL. Besides, SEM and MIP results showed that low dosage of PL could decrease the porosity due to the filling effect. When the dosage of PL in cement exceeds 2.0%, the structure was more loose and porous, attributed to the delayed hydration and air entertainment. The dispersion mechanism was also discussed and ascribed to electrostatic repulsion caused by PL adsorbed on the surface of cement particles and the steric effect due to the branched chains of PL. This study provides a new idea for high-value application of lignin and the promotion of low-carbon building materials by using renewable resources.

Long-Term Hindrance Effects of Algal Biomatter on the Hydration Reactions of Ordinary Portland Cement

The incorporation of carbon-fixing materials such as photosynthetic algae in concrete formulations offers a promising strategy toward mitigating the concerningly high carbon footprint of cement. Prior literature suggests that the introduction of up to 0.5 wt % chlorella biological matter (biomatter) in ordinary Portland cement induces a retardation of the composite cement’s strength evolution while enabling a long-term compressive strength comparable to pure cement at a lower carbon footprint. In this work, we provide insights into the fundamental mechanisms governing this retardation effect and reveal a concentration threshold above which the presence of biomatter completely hinders the hydration reactions. We incorporate Chlorella or Spirulina, two algal species with different morphology and composition, in ordinary Portland cement at concentrations ranging between 0.5 and 15 wt % and study the evolution of mechanical properties of the resulting biocomposites over a period of 91 days. The compressive strength in both sets of biocomposites exhibits a concentration-dependent long-term drastic reduction, which plateaus at 5 wt % biomatter content. At and above 5 wt %, all biocomposites show a strength reduction of more than 80% after 91 days of curing compared to pure cement, indicating a permanent hindrance effect on hardening. Characterization of the hydration kinetics and the cured materials shows that both algal biomatters hinder the hydration reactions of calcium silicates, preventing the formation of calcium hydroxide and calcium silicate hydrate, while the secondary reactions of tricalcium aluminate that form ettringite are not affected. We propose that the alkaline conditions during cement hydration lead to the formation of charged glucose-based carbohydrates, which subsequently create a hydrogen bonding network that ultimately encapsulates calcium silicates. This encapsulation prevents the formation of primary hydrate products and thus blocks the hardening of cement. Furthermore, we observe new hydration products with composition and micromorphology deviating from the expected hardened cement compounds. Our analysis provides fundamental insights into the mechanisms that govern the introduction of two carbon-negative algal species as fillers in cement, which are crucial for enabling strategies to overcome the detrimental effects that those fillers have on the mechanical properties of cement.

Effect of Sodium Gluconate on Properties and Microstructure of Ultra-High-Performance Concrete (UHPC).

The properties of concrete can be significantly affected by sodium gluconate (SG) at very small dosages. In this paper, the effects of SG on the fluidity, setting time, heat of hydration, and strength of ultra-high-performance concrete (UHPC) were studied. The results show that (1) in the plastic stage, SG inhibited the formation of early ettringite (AFt) and delayed the hydration of tricalcium silicate (C3S) and dicalcium silicate (C2S). SG increased the initial fluidity of UHPC without decreasing within 1 h. When the SG dosage was ≥0.06%, the slumps at 30 min and 60 min increased slightly. (2) In the setting hardening stage, the addition of SG inhibited the formation of calcium hydroxide (CH), which significantly extended the setting time of UHPC. When the dosage of SG was 0.15%, the initial and final setting times were 5.0 times and 4.5 times that of the blank group, respectively. SG had no obvious effect on the hydration rate of cement in the accelerated period, but the peak hydration temperature of UHPC was increased when the SG dosage was 0.03~0.12%. (3) In the strength development stage, the 1 d and 3 d strength of UHPC decreased significantly with the increase in the SG dosage. However, SG could promote the formation of AFt at the pores and aggregate interface in the later stage, reduce the porosity of cementite, and improve the compressive strength of UHPC in 28 d, 60 d, and 90 d. When the SG dosage was 0.12%, the 90d strength increased by 13%.

Use of eggshell waste: A green and effective method for the synthesis of pure calcium hydroxide suspensions

This paper presents a rapid method to obtain pure suspensions of Ca(OH)2 dispersed in 2-propanol. To this aim eggshell wastes (CaCO3) were decarbonated to calcium oxide (CaO) followed by sonication-assisted hydrolysis in water/2-propanol to form calcium hydroxide (Ca(OH)2). An important advantage of the method is that it does not require chemical reagents due to the high purity of eggshell in CaCO3. Moreover, CaO is fully converted into Ca(OH)2 which means that purification steps are not needed, as occurs in conventional routes of synthesis. To assess the reliability of the synthetic procedure, the purity and amount of Ca(OH)2 were studied by X-ray diffraction (XRD), infrared spectroscopy (FTIR) and thermal analysis (TG). In addition, the morphology and crystallite size were examined by transmission electron microscopy (TEM) and X-ray diffraction (XRD) using Rietveld refinement method. It was found that sonicated Ca(OH)2 suspensions (5 g/L) were composed of particles that ranged in size from several nanometers to few micrometers. Finally, the suitability of Ca(OH)2 from eggshell to reinforce architectural stone was also studied by microscopy examination, colour change tests, surface hardness and surface erosion measurements. All tests confirmed the consolidation effectiveness was comparable to conventional nanolime treatments and surface erosion was visibly reduced.

Preparation of nano-carbon black and silica fume modified foam concrete: Compressive strength, pore structure and electromagnetic property

In this paper, absorbent nano-carbon black and silica fume are added into foam concrete. Considering hydration products and pore size distribution, the foam concrete compressive strength is analyzed, and its conductivity and electromagnetic parameters are tested. The effects of adding silica fume on the electromagnetic wave loss characteristics of carbon black foam concrete are studied. The results demonstrate that the incorporation of carbon black greatly promotes the formation of calcium hydroxide, ettringite and amorphous calcium silicate hydrate (CSH) during cement hydration, making the foam concrete average pore size larger. Meanwhile, mixed silica fume can offset the adverse effects of carbon black on pore size distribution and improve the compressive strength of carbon black foam concrete. The conductivity of the specimen rises with the increase of carbon black, and conductive percolation occurs at the same time. When the added carbon black is 2 wt%, the foam concrete has adequate ability of electromagnetic wave loss. After being mixed with silica fume, the conductivity of the specimen increases, and the electromagnetic wave loss capacity decreases slightly over the frequency range of 4.0 GHz to 5.0 GHz.

Retardation and compressive strength enhancement effect of upcycling waste carrot as bio-admixture for cement mortars

The use of bio-admixtures instead of traditional chemical admixtures to prepare green concrete has attracted immense attention. In this study, a new and clean method to upcycle waste carrot into a novel natural admixture for cement mortars was proposed, and the effect of carrot extract (CS) on the properties of cement-based materials was systematically studied at the macro and micro levels through multiple means of detection. The results revealed that CS effectively inhibited the early hydration of cement and prolonged its setting time. The setting time of the pastes containing CS was 1.1–2.7 times that recorded for the control group (without CS) (CON), and the retarding effect was positively correlated with CS concentration. The compressive strength of the mortar of the M-CS1 (the value of CS to water was 1:100) group was increased by 12.5%, 11.6%, and 4.5% at 3-, 7-, and 28 d, respectively,which was due to the fact that CS accelerated the generation of calcium hydroxide (CH) and calcium silicate hydrate(C–S–H). In summary, CS can be used as a retarder and compressive strength enhancer in concrete simultaneously, and the experimental results in this study can provide experimental data and a basis for the preparation of green concrete. • The setting time of the pastes containing CS was 1.1–2.7 times that recorded for CON, and the addition of CS with appropriate concentration can also improve the compressive strength of the mortar. • CS contains a large number of hydrophilic group - hydroxyl, which has good water retention performance in cement. • The CS solution did not lead to the formation of new hydration products but promoted the formation of CH and CSH in the system, which has a positive effect on the compressive strength of mortars. • CS can improve the micro pore structure of mortar. • The use of low dose CS exhibited better sustainability and higher cost-effectiveness as confirmed by the economic and environmental analysis.

Comparative Histological Study of Reparative Dentin Formation of Calcium Hydroxide and Zeolite in Pulpotomized Teeth (Histological Study)

Comparative Histological Study of Reparative Dentin Formation of Calcium Hydroxide and Zeolite in Pulpotomized Teeth (Histological Study)

Structural and Optical Properties of Calcium Titanate Prepared from Gypsum

Ceramic materials have been used in various human health-related applications for considerable time. One of the important applications of ceramic materials is in electronics. Our work focuses on calcium titanate (CaTiO3). CaTiO3 is typically created via sintering. Gypsum particles is used to form calcium hydroxide, which is then combined with titanium dioxide to form rutile crystals. Thereafter, calcination is performed at 900°C, 1000°C, and 1100°C for 2 h. X-ray diffraction is employed to track the evolution of the CaTiO3 phase. Scanning electron microscopy is used to characterize the morphologies of the different preparation steps. As the calcination temperature increases from 900°C to 1000°C, the crystallite size of CaTiO3 increases from 35 nm to 45 nm. Furthermore, the energy gaps of the CaTiO3 powders obtained after calcination at 900°C and 1000°C are 5.32 eV and 5.43 eV, respectively, and their particle sizes are 150–200 nm and 200–300 nm, respectively.

Present status and future directions: Hydraulic materials for endodontic use.

BackgroundHydraulic materials are used in Endodontics due to their hydration characteristics namely the formation of calcium hydroxide when mixing with water and also because of their hydraulic properties. These materials are presented in various consistencies and delivery methods. They are composed primarily of tricalcium and dicalcium silicate, and also include a radiopacifier, additives and an aqueous or a non‐aqueous vehicle. Only materials whose primary reaction is with water can be classified as hydraulic.ObjectivesReview of the classification of hydraulic materials by Camilleri and the literature pertaining to specific uses of hydraulic cements in endodontics namely intra‐coronal, intra‐radicular and extra‐radicular. Review of the literature on the material properties linked to specific uses providing the current status of these materials after which future trends and gaps in knowledge could be identified.MethodsThe literature was reviewed using PUBMED, and for each clinical use, the in vitro properties such as physical, chemical, biological and antimicrobial characteristics and clinical data were extracted and evaluated.ResultsA large number of publications were retrieved for each clinical use and these were grouped depending on the property type being investigated.ConclusionsThe hydraulic cements have made a difference in clinical outcomes. The main shortcoming is the poor testing methodologies employed which provide very limited information and also inhibits adequate clinical translation. Furthermore, the clinical protocols need to be updated to enable the materials to be employed effectively.

Efficacy of Bioceramic and Calcium Hydroxide-Based Root Canal Sealers against Pathogenic Endodontic Biofilms: An In vitro Study.

Complete eradication of root canal pathogens cannot be predictably achieved by chemomechanical preparation and root canal disinfection. Therefore, an obturation material that has superior antimicrobial activity and sealing ability is required to inactivate residual microbes and prevent them from reentering the root canal system. Recently developed bioceramic root canal sealers are hydraulic cement which form calcium hydroxide during the hydration process. Like calcium hydroxide sealers, they exert an antimicrobial effect by releasing hydroxyl ions and increasing the pH. The objective of this study was to evaluate and compare the antimicrobial activity of a calcium hydroxide-based sealer and two bioceramic sealers against Porphyromonas gingivalis, Enterococcus faecalis, and Candida albicans biofilms. The sealers were dissolved in sterile saline to obtain supernatants. Biofilm formation assays, colony counting, and real-time polymerase chain reaction (PCR) were performed to evaluate the antimicrobial activity of each supernatant. The data were analyzed using one-way analysis of variance. All sealers exerted effects against all three microbial biofilms. The biofilm formation assays showed that the bioceramic sealers were more effective against P. gingivalis and E. faecalis biofilms. In contrast, colony counting and real-time PCR showed that the calcium hydroxide sealer was significantly more effective than the bioceramic sealers. All tests showed that the calcium hydroxide sealer was more effective against C. albicans, with the colony count and real-time PCR results showing statistically significant differences. The calcium hydroxide-based sealer was more effective than the bioceramic sealers in eradicating pathogenic root canal biofilms.

Eco-valorification of marine shells by hydrothermal conversion in alkaline media

Marine shells are a natural, cheap, abundant and renewable resource, which can be used to produce useful materials, such as for the construction industry. The present study focuses on the transformation of Mya arenaria exoskeletons from the Black Sea into calcium hydroxide by using low-temperature hydrothermal synthesis. In contrast with other methods, this energy-saving process does not involve calcination of shells prior to the hydrothermal treatment. XRD results show the formation of calcium hydroxide with preferential orientation and interesting atypical morphology, which is strongly influenced by the composition of the reaction medium.

Effect of temperature on stress strain behavior of high calcium fly ash and alccofine blended high strength concrete

In present study, the effect of temperature on stress–strain response under monotonic compressive loading is studied for two blended high strength concrete (HSC, viz., high calcium fly ash blended HSC (FC-HSC) and alccofine blended HSC (AL-HSC)) mixes. The experimental studies have been carried out with a 100 mm × 100 mm × 100 mm cube specimen and tested at 28 day of curing. For each mix, four sets of specimens, including control specimen and those exposed to elevated temperatures of 80 °C, 140 °C and 160 °C for 6 h were considered for the study. The stress–strain behavior of HSC mixes at elevated temperatures exhibits a distinct effect of material composition. The increasing exposure temperature increases peak stress for AL-HSC, whereas it initially decreases and then increases for FC-HSC. The results from the study confirm that elevated temperature contributes to stiffening of the pre-peak region, but the effect on peak stress is influenced by the material composition. The effect of elevated temperature on microstructural change is evaluated through thermo gravimetric analysis and the results are compared for FC-HSC and AL-HSC. The weight loss (30–160 °C) representing calcium silicate hydrate (CSH) degradation decreases with increasing exposure temperature for FC-HSC, whereas it remains range bound for AL-HSC. On the other hand, weight loss (400–500 °C) representing degradation of calcium hydroxide (CH) remains range bound for FC-HSC while it increases with increasing exposure temperature for AL-HSC. The observed results suggest that increasing exposure temperature contributes to CSH degradation in FC-HSC, whereas it enhances CH formation for AL-HSC. The study results provide useful insight on the effect of elevated temperature on the stress–strain behavior of blended HSC with flyash and alccofine.

Towards the development of sustainable concrete incorporating waste tyre rubbers: A long-term study of physical, mechanical & durability properties and environmental impact

The dramatic increase in the demand for vehicle tyres and consequently the rapid rise in associated waste rubber has been a concern for several decades. Rubber disposal has adverse effects on the environment, human health and a detrimental effect on sustainable development across the world. This paper investigates the effectiveness of a sodium hydroxide treatment method for waste rubber in addition to the utilisation of silica fume to improve the interfacial transition zone between the rubber and cement matrix. This has been shown to have important implication for the long-term development of physical and mechanical properties of concrete aged for 2 years. This study emphasises that while satisfactory improvements are attained through the rubber treatment alone, the actual performance of rubberized concrete containing silica fume could only be investigated over the long term owing to the slow pozzolanic reaction and its dependency on the formation of calcium hydroxide. The pre-treatment of rubber and more specifically the utilisation of silica fume improved the durability of concrete over rubber replacement levels from ∼20% to 40%. Long-term thermal conductivity and sound permeability of concrete containing tyre rubber were shown to have important consequences in energy conservation and social sustainability in construction practice. Results reported on the cost efficiency and consequently the CO2 emissions of concrete containing rubber do not only enhance awareness of the development of sustainable construction materials but also lead a cleaner alternative waste management route for tyre rubber.

Environmental opportunities and challenges of utilizing unactivated calcium peroxide to treat soils co-contaminated with mixed chlorinated organic compounds

Calcium peroxide (CaO2) has been proven to oxidize various organic pollutants when they exist as a single class of compounds. However, there is a lack of research on the potential of unactivated CaO2 to treat mixed chlorinated organic pollutants in soils. This study examined the potential of CaO2 in treating soils co-contaminated with p-dichlorobenzene (p-DCB) and p-chloromethane cresol (PCMC). The effects of CaO2 dosage and treatment duration on the rate of degradation were investigated. Furthermore, the collateral effects of the treatment on treated soil characteristics were studied. The result showed that unactivated CaO2 could oxidize mixed chlorinated organic compounds in wet soils. More than 69% of the pollutants in the wet soil were mineralized following 21 days of treatment with 3% (w/w) CaO2. The hydroxyl radicals played a significant role in the degradation process among the other decomposition products of hydrogen peroxide. Following the oxidation process, the treated soil pH was increased due to the formation of calcium hydroxide. Soil organic matter, cation exchange capacity, soil organic carbon, total nitrogen, and certain soil enzyme activities of the treated soil were decreased. However, the collateral effects of the system on electrical conductivity, available phosphorus, and particle size distribution of the treated soil were not significant. Likewise, since no significant release of heavy metals was seen in the treated soil matrix, the likelihood of metal ions as co-pollutants after treatment was low. Therefore, CaO2 can be a better alternative for treating industrial sites co-contaminated with chlorinated organic compounds.

Experimental Study on the Effect of Conductive Carbon Black Super-P on the Properties of Composite Mortar

Conductive carbon black Super-P (CSP) is a kind of nanomaterial, which is often used as conductive agent. It has excellent conductivity and low production cost. In this paper, CSP was used as the admixture to prepare composite mortar (with the specific gravity of cementitious material). The consistency, mechanical properties, electrical conductivity and temperature sensitivity of composite mortar were studied. The mechanism of CSP was analyzed by scanning electron microscope (SEM) and X-ray diffraction (XRD). The results show that the consistency of composite mortar decreases with the addition of CSP. The mechanical properties of composite mortar first increase and then decrease with the increase of CSP content. The addition of CSP greatly improves the conductivity of mortar. When the CSP content is 0.5–2%, the resistivity decreases rapidly and the seepage threshold appears. When the content of the mixture is large, the influence of different curing conditions on resistivity is small. SEM and XRD analysis show that CSP can fill micro pores and conduct electricity through tunnels, and does not change the composition of hydration products of composite mortar, and the formation of calcium hydroxide can be inhibited when the content is small. This paper explores the properties of CSP composite mortar, which provides theoretical and experimental basis for the preparation and application of conductive mortar.