Setting Time Of Cement Research Articles

An injectable tricalcium silicate/α-tricalcium phosphate/hydroxypropyl methylcellulose biocomposite with improved physicochemical properties and osteoinductive activity for endodontic application.

Tricalcium silicate (TCS)-based bioactive cements have attracted great attention for various endodontic applications owing to their hydraulic property, sealing ability and biological properties. Nevertheless, poor handling property and anti-washout ability are the main challenges for traditional TCS-based cements and their osteoinductive capacity needs enhance for accelerated pulpal and periapical tissue repair/regeneration. Herein, we developed an injectable TCS/α-tricalcium phosphate (α-TCP)/hydroxypropyl methylcellulose (HPMC) biocomposite with improved physicochemical properties and osteoinductive ability via the incorporation of α-TCP/HPMC. HPMC endowed TCS/α-TCP cements excellent injectablity (above 93 %) and anti-washout property. The introduction of 10 wt% α-TCP shortened the setting time of cements and obtained high compressive strength while an excess quantity of α-TCP could compromise its setting property. TCS/α-TCP/HPMC cements had good apatite formation ability and dentin interface adhesion. Moreover, TCS/10α-TCP/HPMC could significantly enhance cell viability and osteogenic differentiation of osteoblasts by increasing alkaline phosphatase (ALP) activity, collagen secretion, and extracellular matrix (ECM) mineralization and up-regulating the osteogenesis-related proteins and gene expression. These results indicated that the injectable TCS/10α-TCP/HPMC biocomposite is a promising candidate for endodontic uses.

An investigation into the microstructural evolution and shrinkage control in internally cured mortars with milkweed fibres

This study presented a significant advancement in the use of Milkweed (MW) fibres as internal curing agents in low water-to-cement (w/c) cementitious materials. The research focused on how different pre-treated MW fibres, with different composition, can impact internal curing efficacy in reducing autogenous shrinkage of cement mortars. In addition, the hydration behaviour and microstructural development were revealed using a series of tests including setting time, compressive strength, flexural strength, scanning electron microscopy (SEM), and thermogravimetric analysis (TGA/DTG). A key finding of this study is the remarkable reduction in autogenous shrinkage, with using 0.1 % wt. pre-treated MW fibres leading to up to 28 % reduction at 7 days, compared to plain mortars. Furthermore, internal curing effect resulted in narrowing the compressive strength gap between the reference mixes and those with pre-treated MW fibres in the later stages of hydration. It was also found that the removal of hemicellulose through hybrid treatment can reduce the delay in the final setting time of cement from 45 minutes to 18 minutes. Additionally, while the incorporation of N- and HT-treated MW fibres had negligible effects on drying shrinkage, the inclusion of HY-treated MW fibres led to a 15 % increase in drying shrinkage at 7 days. This difference in behaviour was attributed to the presence of lignin in N- and HT-treated fibres. Lignin was found to play a crucial role in influencing the drying shrinkage, microstructural development, and mechanical properties of MW fibre-incorporated cementitious mixes. Acting as a protective barrier, lignin shielded the MW fibres from cement infiltration into their lumina. Moreover, it served as both a physical and chemical barrier, reducing moisture transport through the capillary network during drying. In conclusion, this study demonstrated the potential of using pre-treated MW fibres as internal curing agents to effectively reduce autogenous shrinkage, with minimal compromise in terms of the compressive strength of cementitious composites.

ИСПОЛЬЗОВАНИЕ МЕТОДА ОПРЕДЕЛЕНИЯ ВОДООТДЕЛЕНИЯ ЦЕМЕНТА ПРИ ВХОДНОМ КОНТРОЛЕ КАЧЕСТВА В ПРОИЗВОДСТВЕ БЕТОНА

Fresh cement paste bleeding is one of the basic quality indicators, which, however, is not used for cements intended for the production of ordinary concrete mixtures. In some cases, during input inspection, it is necessary to obtain information on the quality of cement and its suitability for use in specific concrete mix compositions with minimal labor costs. Determining water separation allows to quickly obtain data on both the amount of bleeding water separation and its kinetics. The basic methodology is the standard method for determining the amount of water separation in GOST 310.6-2020, which additionally includes measurements of the height of the cement paste column, which allows plotting a water separation curve. In modified methods, measuring cylinders of various volumes were used. Statistical data on water separation of cement pastes from production batches of various plants are collected and presented. The relationship between water separation and normal consistency and setting time of cement is studied. The effect of a long (up to 5 months) shelf life of cements on the amount of water separation is studied. The geometric factors influencing the amount of water separation and the kinetics of the process are considered: the height of the cement paste column, the dimensions of the measuring cylinder. The influence of the initial water-cement ratio of the cement paste on the amount of water separation is studied. A three-stage process of water separation of cement is established with the prevalence of the channel type of water separation. A nonlinear decrease in water separation is noted with a decrease in the water-cement ratio. The obtained basic kinetic dependencies of water separation can be used to predict the water separation of concrete mixtures.

Effect of Phosphoric Acid and Soluble Phosphate on the Properties of Magnesium Oxychloride Cement.

This study investigates the effects of phosphoric acid (H3PO4), potassium dihydrogen phosphate (KH2PO4) and sodium dihydrogen phosphate (NaH2PO4) admixtures on the setting time, compressive strength and water resistance of magnesium oxychloride cement (MOC). MOC samples incorporating different admixtures are prepared, and their hydration products and microstructures are studied via X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results indicate that the addition of H3PO4, KH2PO4 and NaH2PO4 reduces the initial and final setting times and decreases the compressive strength. However, the compressive strength of MOC is higher than 30.00 MPa with the addition of 2.0 wt.% phosphoric acid and its phosphate after 14 days of air curing. The water resistance of modified MOC slurries is significantly improved. The softening coefficient of MOC with 2.0 wt.% H3PO4 is 1.2 after 14 days of water immersion, which is 3.44 times higher than that of the neat MOC. The enhancement in water resistance is attributed to the formation of amorphous gel facilitated by H3PO4, KH2PO4 and NaH2PO4. Furthermore, the improvement in water resistance is manifested as H3PO4 > KH2PO4 > NaH2PO4.

The Effects of Metakaolin on the Properties of Magnesium Sulphoaluminate Cement.

Magnesium sulphoaluminate (MSA) cement has good bonding properties and is suitable as an inorganic adhesive for repairing materials in civil engineering. However, there are still some problems with its use, such as its insufficient 1 day (d) strength and poor volumetric stability. This paper aims to investigate the influences of metakaolin (MK) on the physical and mechanical properties of magnesium sulphoaluminate (MSA) cement. The hydration products and microstructures of typical MSA cement samples were also analysed using X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS). The results showed that the addition of metakaolin reduces the fluidity and shortens the setting time of the MSA cement. The initial setting time and final setting time shortened maximally by 15-27 min and 25-48 min, respectively, with the addition of 10-30% metakaolin. Moreover, the compressive strength and flexural strength of the MSA cement improved significantly with the addition of 10-30% metakaolin at a curing age of 1 d. Compared with the compressive and flexural strengths of the control sample at 1 d, the compressive strengths of the modified samples showed obvious increases of 98%, 101%, and 109%, and the flexural strengths increased by 39%, 31%, and 26%, respectively, although they decreased slightly when the curing ages were 7 d, 14 d, and 28 d. The addition of 10% metakaolin improved the water resistance of the MSA cement immersed in water for 7 d and resulted in even higher water resistance at 28 d. The addition of 10-30% metakaolin improved the volumetric stability of the MSA cement with increasing dosages before 28 d of ageing. XRD and SEM-EDS analyses showed that the metakaolin accelerated the early hydration reaction and optimised the phase composition of the MSA cement. The results indicate that the addition of 10-20% metakaolin improved the strength after 1 d of ageing, water resistance, and volumetric stability of the MSA cement, providing theoretical support for the application of MAS cement as an inorganic bonding agent for repairing materials.

Study on the preparation and properties of high-performance foamed cement by multi-factor optimization

The promotion of high-performance foamed cement in engineering is consistent with the objectives of energy conservation and sustainable development. In this work, the effects of the water–binder ratio, foam–grout ratio, mineral powder content and magnesium oxide content on the performance of foamed cement were studied. High-performance foamed cement was prepared considering the above four factors. The results indicated that the pore structure of the foamed cement was effectively modified by adjusting the water–binder and foam–grout ratios, while its compressive strength increased and its setting time decreased when mineral powder and magnesium oxide were added. Pore structure and scanning electron microscopy experiments revealed that the surface of the high-performance foamed cement was covered with many hydration products of mineral powder and magnesium oxide, resulting in a more compact and uniform structure. Simultaneously, these hydration products effectively filled pores with diameters ranging from 0 to 0.2 mm in the high-performance foamed cement, refining its pore structure and thereby enhancing its waterproof performance and drywet cycling stability. Compared with those of commercial foamed cement, the setting time of the high-performance foamed cement was 23.48 % shorter, and its compressive strengths at 1 d and 7 d were 245.78 % and 178.62 % greater, respectively. Furthermore, the production cost per cubic meter of the high-performance foamed cement was 107.29 RMB less than that of ordinary cement. In brief, the high-performance foamed cement can be widely used in a variety of engineering applications because of its performance and economic benefits.

Reinforcement of hydroxyapatite bone cement via thin glycerol-citrate polyester infiltration: Microstructural, mechanical and in-vitro evaluation

The development of calcium phosphate cements (CPCs) incorporating biopolymers, such as thermoplastic polylactides, is known as an efficient strategy to enhance the physico-chemical, biological, and mechanical properties of CPCs. However, the use of thermosetting polyol citrates as fillers in CPCs has rarely been reported. Hence, the main goal of the present work was to produce composite CPCs based on tetracalcium phosphate–monetite cement matrix (C) and glycerol-citrate polyester (GCA) and to thoroughly study the effect of GCA addition on microstructural, micro, and nano-mechanical as well as in-vitro cellular properties of final cement composites. The GCA polymer was synthesized by esterification of glycerol with citric acid and coated on the C cement powder matrix at a concentration of 2.5 wt% by infiltration in ethanol solution. Two systems were prepared, by drying the composite powder at 105 and 170 °C (denoted as GCA/C105 and GCA/C170), while the respective composite cements were produced by mixing the powders with the 2 wt% of NaH2PO4 liquid phase. The results showed that the GCA polyester had no significant effect on the hydrolysis and transformation of the original cement matrix, and the nanocrystalline hydroxyapatite (Hap) was found as the main hydration product in all types of cement. The cement setting time decreased slightly with the GCA addition. On the other hand, a significant increase in mechanical properties was reached by introducing the GCA polyester into the CPC matrix, achieving more than a 70 % increase in the compressive strength, and about 50 % and 20 % in micro and nanohardness values compared to that obtained for the original C cement sample. The nanoindentation analysis revealed that the improved compressive strength and hardness were due to the stronger boundaries between the platelet-like hydroxyapatite particles in GCA-doped cements and partially caused by the denser, less porous, and more compact microstructures. The results of in-vitro cytotoxicity testing revealed high proliferation activity of the osteoblastic cells in all cement extracts, providing useful information for designing novel composite cements with the potential to be applied as bone substitute materials.

The Optimum Interval Time of Layered Cement Composites with the Incorporation of Edge-Oxidized Graphene Oxide

The current research focuses on the effect of incorporating edge-oxidized graphene oxide (EOGO) on the performance of layered cement composites cast at different times. The feature of producing flower-shaped hydrated cement products is exploited to enhance the contact surface of two different cement composites. In the current study, the interval time of casting cement composites is the crucial parameter investigated. Consequently, a layer of cement paste with EOGO is cast above a layer of cement mortar where the amount of EOGO of 0.10% by the cement weight is fixed for all mixtures. Also, four different interval times based on cement setting time are considered, namely immediately, 6 h, 12 h, and 1 day. Similar mixtures are prepared but without adding EOGO for comparison purposes. The results show that EOGO is capable of enhancing the contact surface of layered cement composites by strengthening the split strength of two different layers (between 12 and 29%). Moreover, casting the paste layer containing EOGO after 6 h of mortar layer seems to be the optimum interval time among others by improving compressive strength (by 29%) and residual strength (by 34%) and not affecting flexural strength and porosity percentage.

ZrO2 and ZnO nanoparticles effect on setting time, microhardness, and compressive strength of calcium-enriched-mixture cement

Aim: Calcium-enriched mixture (CEM) cement is an endodontic biomaterial; however, enhancing its physical/mechanical properties remains a challenge. This in vitro study investigates the influence of zirconium oxide (ZrO2) and zinc oxide (ZnO) nanoparticles on the setting time, microhardness, and compressive strength of CEM cement. Methods: Four different groups of CEM cement were prepared: a control group without nanoparticles, two groups with ZrO2 or ZnO, and a group with a combination of nanoparticles. The nanoparticles were added to the powder in predetermined concentrations. The setting time was evaluated using the Gilmore needle method, while microhardness and compressive strength were determined using Vickers hardness and a universal testing machine, respectively. Results: The incorporation of ZnO slightly reduced the setting time, while the addition of ZrO2 significantly prolonged it compared to the control group. Interestingly, the combination of both nanoparticles exhibited a setting time comparable to that of the control group. Regarding the microhardness and compressive strength, both ZrO2 and ZnO significantly improved these properties compared to the control group. The combination of both nanoparticles showed the highest microhardness and compressive strength values among all groups. Conclusions: The addition of nanoparticles to CEM cement effectively modifies its physical and mechanical properties. The optimal combination of these nanoparticles can potentially achieve an improved balance between setting time and enhanced mechanical performance.

Influence of SiO2@CaAl-LDH core-shell nanocomposite on rheology and hydration of cement

Nano-SiO2@ Layered double hydroxide (LDH) core-shell nanocomposite shows a promising application as high-efficiency chloride adsorbent in cement-based materials. However, its effect on rheology and hydration of cement is not yet known. In this study, the SiO2@CaAl- LDH core-shell nanocomposite by growing the LDH on nano-SiO2 surface was firstly created using in-situ co-precipitation method. The influence of as-synthesized nanocomposite on the rheology and hydration of cement was systematacially researched through contrasting experiments. Besides, microstructures of SiO2@LDH and its cement paste were characterized. The results show that the LDH with petal-like shape on the nano-SiO2 surface exhibits a higher specific area than pure nano-SiO2 and LDH alone. The addition of SiO2@CaAl-LDH core-shell material significantly shortens the initial and final setting time of cement and increases cement hydration heat generation rate and the total exothermic amount for 72 h. Contrary to the mixture of LDH, the additions of nano-SiO2 and SiO2@LDH increases the yield stress and plastic viscosity of cement paste. Compared to the additions of LDH and SiO2, the addition of SiO2@LDH more significantly enhances the strength of cement, of which the highest increasing level reaches 66 % at the early age of 1 d. In addition, SiO2@LDH exhibits the best refinement effect on the pore structure of cement because of the synergetic effect between the LDH and nano-SiO2.

Assessing setting times of cementitious materials using semi-adiabatic calorimetry

The most common methods for the determination of setting times of cements are the various penetration tests. One of the most important of these is the Vicat method, which is the current standard measurement (EN 196-3) to determine the setting time of cement. However, there are alternative methods that can be used to monitor the setting process and eliminate several issues that arise from the Vicat method, such as intermittent measurement, measurability of cement pastes of non-standard consistency, testing mortars and concretes.One such method is semi-adiabatic calorimetry (SAC), which can be an alternative to penetration tests in appropriate circumstances. In this study, determination of setting times of two sources of CEM I 42.5 N cement was observed, using semi-adiabatic calorimetry at different (0.25; 0.27; 0.29; and, 0.31) water to cement ratios (w/c). During our measurements, we observed that the ratio between the setting time of a given source of cement and the time it took to reach the maximum rate of heat development was almost constant for the same cement and w/c ratio, which enables a simple and inexpensive routine measurement of setting times of Portland cement.

Synergistic Effect of Polyethylene Glycol and Lactic Acid on Handling Properties and Antibacterial Efficacy of Premixed Calcium Silicate Cement.

Calcium silicate (CaSi) bone cement with antibacterial and osteogenic properties has attracted significant interest. However, there is a need to develop a variety of new premixed bone cement to meet the clinical requirements of fast setting time, ease of handling, and efficient antibacterial properties. In this study, different volume ratios of polyethylene glycol (PEG) and lactic acid liquids were added to calcium silicate, and the effects of varying liquid-to-powder ratios (L/P) were examined. This study assessed the physicochemical properties, cytotoxicity, and antibacterial activity against S. aureus and E. coli of this premixed cement. The results from the experiments indicated that lactic acid significantly reduced the setting time of the CaSi-based cement and enhanced its mechanical strength. Furthermore, the appropriate concentration of lactic acid and matching L/P ratio improved its washout resistance. The cell viability of all premixed cement was found to be over 80%. The premixed cement containing PEG and lactic acid exhibited superior antibacterial properties compared to the CaSi control. Based on its setting time, washout resistance, and antibacterial activity, a premixed cement with a liquid phase of 80% PEG and 20% lactic acid at an L/P ratio of 0.4 appeared promising for use in dental and orthopedic practice.

Preparation and property studies of ferric sulfoaluminate cement based on Bayer red mud and phosphogypsum.

The Bayer red mud (RM) and phosphogypsum (PG) accumulation have caused significant environmental contamination. However, practical and effective resource utilization technologies are still lacking currently. This work aims to develop ferric sulfoaluminate cement (FSAC) employing low-cost materials including Bayer red mud, phosphogypsum, and other materials. This method effectively improves the utilization rate of Bayer red mud and phosphogypsum. Under the premise of ensuring the performance of FSAC, the utilization rate of solid waste can reach up to 48.56%. The effects of different red mud dosages on cement mineral formation, workability, and mechanical properties are investigated. Then, untreated phosphogypsum is adopted as a retarder for FSAC, and the hydration process, working properties, mechanical properties, types of hydration products, and morphology of FSAC are explored. The results suggest that the crystal transformation of Ye'elemite is promoted with the increase of Bayer red mud content. Cubic crystal system Ye'elemite with higher hydration activity is generated, which increases the early strength of cement but greatly reduces the setting time, hindering the later strength growth. Untreated phosphogypsum can effectively delay the early hydration process of FSAC, prolong the setting time of cement, and increase the strength of FSAC in the later stage. When the dosage of Bayer red mud and phosphogypsum is 17.64% and 9.21%, respectively, with phosphogypsum dosage of 20%, the prepared FSAC has satisfactory mechanical properties, and the 3-day and 90-day compressive strengths are 34.6 MPa and 57.1 MPa, respectively. In addition, the study of heavy metal leaching indicates that the FSAC prepared by Bayer red mud, phosphogypsum, and other raw materials will generate no environment pollution, and the solidification of heavy metal elements in the cement slurry is superior.

All-in-one strategy to develop a near-infrared triggered multifunctional bioactive magnesium phosphate bone cement for bone repair

Bone cement is widely used in clinical with optimistic filling and mechanical properties. However, the setting time of bone cement is difficult to accurately control, and the existing bone cements exhibit limited therapeutic functionalities. In response to these challenges, we designed and synthesized Nd-doped whitlockite (Nd-WH), endowing bone cement with photothermal-responsive and fluorescence imaging capabilities. The doping amount and photothermal properties of Nd-doped whitlockite were studied, and the composite bone cement was prepared. The results showed that the setting time of bone cement could be regulated by near infrared irradiation, and the multiple functions of promoting osteogenic differentiation, antibacterial and anti-tumor could be realized by adjusting the power and irradiation time of near infrared. By incorporating Nd-doped whitlockite and bone cement, we developed an all-in-one strategy to achieve setting time control, enhanced osteogenic ability, tumor cell clearance, bacterial clearance, and bone tissue regeneration. The optimized physical and mechanical properties of composite bone cement ensure adaptability and plasticity. In vitro and in vivo experiments validated the effectiveness of this bone cement platform for bone repair, tumor cell clearance and bacterial clearance. The universal methods to regulate the setting time and function of bone cement by photothermal effect has potential in orthopedic surgery and is expected to be a breakthrough in the field of bone defect repair. Further research and clinical validation are needed to ensure its safety, efficacy and sustainability. Statement of significanceBone cement is a valuable clinical material. However, the setting time of bone cement is difficult to control, and the therapeutic function of existing bone cement is limited. Various studies have shown that the bone repair capacity of bone cements can be enhanced by synergistic stimulatory effects in vivo and ex vivo. Unfortunately, most of the existing photothermal conversion materials are non-degradable and poorly biocompatible. This study provides a bone-like photothermal conversion material with photothermal response and fluorescence imaging properties, and constructed a platform for integrated regulation of the setting time of bone cement and diversification of its functions. Therefore, it helps to design multi-functional bone repair materials that are more convenient and effective in clinical operation.

The influence of accelerators on compressive strength and setting time of cement to achieve high early strength for 3D concrete printing technology

The development of 3D concrete printing (3DCP) technology has completely changed the way that complicated structures are built, it also increases efficiency and lowers costs. Achieving high early setting and early strength in 3DPC are still a considerable difficulty. This study examines the impact of accelerators on the setting time of rapid hardening pozzolana cement. Sodium hydroxide (NaOH), Calcium Chloride (CaCl2), Calcium nitrite (CN), Triethanolamine (TEA), triisopropanolamine (TIPA) were used as an accelerator for this study. The findings show that the addition of accelerators reduces the setting time significantly while also increasing the compressive strength. With the help of the findings, mixed design parameters for 3DCP technology can be optimized, allowing for the rapid curing of durable structures. The practical application and widespread acceptance of 3DCP technology in the construction industry are affected by these findings.

Effects of ambient temperature and compaction delay time on the performance of cement-stabilised sand–gravel and the determination of allowable construction delay time

ABSTRACT Compaction delay time (t d) refers to the period from the mixing of inorganic binder–stabilised materials to the completion of compaction; this process is affected by ambient temperature (T a). To characterise the effects of T a and t d on the performance of cement-stabilised sand–gravel (CSG) during construction, the reliability of the vertical vibration compaction method (VVCM) is evaluated and the effects of T a and t d on the mechanical strength and freeze–thaw resistance of CSG are investigated. Next, a predictive model for the allowable construction delay time is developed based on a non-loss principle with respect to pavement performance. The results show that the correlation between the mechanical strength of CSG laboratory specimens subjected to VVCM and field core samples can reach ∼90%. Higher T a and longer t d significantly reduce the mechanical strength and freeze-thaw resistance of CSG. Notably, when t d exceeds the initial setting time of cement, the average reductions in compressive strength, splitting strength, and freeze-thaw resistance of CSG are ∼29.3%, 31.3%, and 20.4%, respectively. The allowable construction delay time decreases linearly with increasing T a, showing a correlation of up to 99%. The predictive model can effectively determine the allowable construction delay time at any temperature.

Effect of steel slag powder and stone powder by-product from manufactured sand on the mechanical properties and microstructure of cementitious materials

Incorporating steel slag (SS) and stone powder (SP) as supplementary cementitious materials (SCMs) in cement and concrete products is an effective approach to promoting environmental protection. Recently, the effect of using steel slag alone is not satisfactory and the performance of blended cementitious materials is expected to improve after compounding with other admixtures. In this study, steel slag powder (SSP) and SP by-products from manufactured sand were employed with a total dose of less than 30% as a replacement for cement. The results revealed that the blended cementitious materials exhibited excellent mechanical strength and pore structure with the synergistic effect of SSP and SP. Compared to SSP or SP doping alone, the activity index of the composite 25% SSP and 5% SP was higher. SSP offers a considerable retardation effect on cement, while SP has little effect. Conversely, the effect of steel slag on mortar fluidity is neglected and SP decreases the fluidity. When 5% SSP is combined with 5% SP, the initial and final setting times of cement are increased by 39% and 25%, respectively. The reduction in mortar fluidity amounted to an insignificant reduction of only 0.7%, and the strength of the mortar at 28 d and 180 d was only lost by 7% and 5%, respectively. The coaction of 15% SSP and 15% SP was observed to promote the wollastonite generation, enhance the crystallization degree of xonotlite phases, decrease the microcrack widths, and optimize the pore structure of the blended cementitious materials.

Effect of Zinc Ion in Water on Properties of Ordinary Portland cement Concrete

The study is aimed at investigating the effect of presence of Zinc in water on setting times and compressive strength of cement concrete. In the present study, the effect of Zinc (Zn) on setting time and compressive strength of cement is assessed under laboratory conditions. The research program included tests of setting times and Mechanical strengths up to 28 days. In this research, the cement concrete cubes were cast with deionized water and deionized water containing the Zinc ions at various concentrations. The concentrations of Zinc (Zn) tested for different samples are 10, 50, 100, 500, 1000, 2000, 3000, 4000 and 5000 mg/L. The experimental results show that the presence of Zinc in deionized water accelerates both initial and final setting times up to 2000 mg/L. Zinc in deionized water up to 2000 mg/L there is a nominal change in compressive strength at early age (3-day). Beyond 2000 mg/L there is a significant change in the compressive strength at early ages as well as 28-day. Comparisons of the Zinc with those of control mix levels reveal that the presence of Zinc increases the compressive strength. The rate of increase in compressive strength is with increase in concentration of Zinc.

Compressive Strength Of Concrete The Time Setting Of Application Of Plastiment® P-121 Additive Mixture

Infrastructure growth requires large quantities of concrete, a problem of concern distance between the batching plant and location of different casting locations, the process mixing and transporting to casting location requires time that can exceed the cement setting time. Plastiment helps improve the strength, durability and general quality of concrete. This research aims to determine the compressive strength of concrete at setting times of 60, 90 and 120 minutes using 150 mm x 300 mm specimens with variations in addition of plastiment of 0.20% and 0.40% of the cement weight. Primary data the form of material testing data and concrete compressive strength for each variation and secondary data is in the form of additives and the properties of cement used. The test results show that the compressive strength of concrete at 60, 90 and 120 minutes by adding Plastiment® P-121R at a variation of 0.20% is 17.55, 18.12 and 18.85 MPa while giving a dose of 0.40% is 17 .27, 19.82 and 22.08 MPa. Addition of plaster can meet the slump value requirements at each time variation and in contrast to normal concrete the slump value is not met at each time variation with the concrete having dried during mixing.

Machine learning for optimal ultra-fine cement plugging system in simulated high permeability sandstone reservoirs

The properties of a cement system dictate its potential applications, yet creating a reliable cement plugging system with controllable setting times, robust injection capacity, and high compressive strength often requires a lot of time and resources in advanced oilfield development. To address this issue, a machine learning-based XGBoost model was created to optimize plugging system performance, reduce costs, and enhance efficiency by analysing the initial setting time, final setting time, viscosity, and compressive strength of ultra-fine cement. The results demonstrate an impressive accuracy of 96.08%, 96.10%, 94.35%, and 90.42% for these respective parameters, with a prediction time of 0.0068 seconds. In response to sandstone reservoirs with permeability greater than 500 mD, an intelligent optimization integrated model was established, resulting in three plugging system formulations that meet the requirements. The injection speed was 1 mL/min and the slug combination used was 0.2PV polymer and 0.7PV plugging system. The maximum injection pressure change recorded remained below 0.8 MPa. The plugging rate achieved was over 90%, reaching a maximum of 96.28%. This study provides theoretical guidance for the construction and injection process in the mining field test area and also offers valuable insights for the intelligent development of oilfields.