Processes
·
2025
·Vol. 13
·期 3
·922
·
IF 2.8
Xu Chen,Xiangpeng Zhu,Cheng Gan,Yigang Li,Diren Liu
The stability of cement slurries under high-temperature conditions poses a significant engineering challenge in cementing operations. This study explored the development of a novel tetrameric thermosensitive thickening polymer (TTSTC) as a solution to this problem. Aqueous free radical polymerization was employed to synthesize the polymer. The base monomers 2-acrylamido-2-methylpropanesulfonic acid (AMPS) and acrylamide (AM) were employed, in conjunction with the long-chain thermosensitive monomers octadecyldimethylallylammonium chloride (C18DMAAC) and N-vinylpyrrolidone (NVP). The optimal synthesis conditions were determined by orthogonal experiments as follows: monomer molar ratio (AM:AMPS:C18DMAAC:NVP) = 15:10:5:5, initiator concentration of 16 wt%, cross-linker concentration of 0.45 wt%, pH 6, and polymerization temperature of 60 °C. The chemical structure of TTSTC was characterized by Fourier transform infrared spectroscopy (FT-IR), proton nuclear magnetic resonance (1H-NMR), gel permeation chromatography, scanning electron microscopy, Zeta potential, and particle size measurement. The results verified the successful synthesis of the target polymer. Its thermal stability, thermosensitive thickening behavior, and salinity resistance were systematically investigated. Furthermore, the impact of TTSTC on the settling stability, rheological characteristics, and compressive strength of cement paste was assessed. The experimental findings demonstrated that TTSTC displayed noteworthy thermosensitive thickening properties at temperatures up to 279 °C, pH values ranging from 11 to 13, and NaCl/CaCl2concentrations between 0.05 and 0.5 g/L. The optimal performance of TTSTC was observed at mass fractions ranging from 0.6 to 0.8 wt%. When incorporated into the slurry at 0.6–1.0 wt%, TTSTC significantly improved the slurry settling stability, thickening properties, and 28d compressive strength at elevated temperatures compared with the control. When comparing the temperature-sensitive thickening performance of the newly developed treatment agent with that of the commercially available xanthan gum thickener, the results showed that for the cement slurry system containing the new treatment agent at a mass fraction of 0.6%, the reduction in consistency was 30.9% less than that of the cement slurry system with xanthan gum at a mass fraction of 0.6%. These findings indicate that TTSTC has the potential to function as a highly effective additive in cementing operations conducted in extreme environments, thereby enhancing the stability and dependability of such operations.
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF MATERIALS IN CIVIL ENGINEERING
·
2022
·Vol. 34
·期 7
·04022148
·
IF 3.651
Min Qiao,Jian Chen,Nanxiao Gao,Guangcheng Shan,Jingzhi Wu,Bosong Zhu,Qianping Ran
To explore the potential application of high-performance viscosity-modifying admixtures (VMAs) is of great importance. In this work, the effects of the adsorption group and molecular weight of VMAs on the properties of fresh cement paste were studied. A series of copolymers having similar molecular weights but different adsorption groups (carboxyl, sulfonic, and quaternary ammonium groups) were compared for the first time. A series of copolymers having the same chemical structure but different molecular weights were also compared. The adsorption, fluidity, bleeding, and rheological properties of the fresh cement paste mixed with different copolymers were tested. The results show that the copolymer, having stronger adsorption group (carboxyl group) and higher molecular weight, could decrease the bleeding and fluidity while enhancing the stability of the fresh cement paste more effectively. The study may help explore ideal materials for the design and preparation of synthetic polymer VMAs.
研究领域:
材料科学
·
土木工程
✓ 已验证
DOI
高影响因子
MATERIALS AND STRUCTURES
·
2019
·Vol. 53
·期 1
·1-12
·
IF 2.548
Liu Xin,Feng Pan,Shu Xin,Ran Qianping
The agglomeration of nano particles in cement systems remains a major challenge for their wide use in construction materials. A method of preparing highly dispersed nano-SiO 2 in cement paste is introduced in this paper, and the effects of modified nano-SiO 2 (SiO 2 @PCE) with a core–shell structure on cement hydration and microstructure development were investigated by isothermal calorimetry, quantitative X-ray diffraction, thermogravimetric analysis, scanning electron microscopy and nanoindentation. The results show that well-dispersed nano-SiO 2 @PCE particles in a cement system can significantly accelerate cement hydration at an early age. The highly dispersed nano-SiO 2 @PCE particles refine the pore structure of the hardened cement paste. More specifically, the number of harmless and less-harmless pores is increased, whereas the number of harmful and more-harmful pores is reduced. In addition, the proportion of high-density C–S–H and low-density C–S–H in the hardened cement paste at an early age increases by 69% and decreases by 27%, respectively, with the addition of 1.5% nano-SiO 2 @PCE. Through the seeding effect, cement hydration is accelerated pronouncedly with the addition of highly dispersed SiO 2 @PCE nano particles. In addition, the stiffness of the paste is enhanced by the pozzolanic reaction between SiO 2 @PCE and portlandite.
研究领域:
材料科学
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土木工程
✓ 已验证
产品关联
DOI
高影响因子
Geoenergy Science and Engineering
·
2023
·
IF 0
Wenchuan Wu,Xiaorong Yu,Anbang Hu,Han Yan,Zhengliang Dong,Huan Yang,Gaoshen Su
Amphoteric retarder (AIDA) was prepared by radical copolymerization of 2-acrylamido-2-methyl propane sulfonic acid (AMPS), itaconic acid (IA), 2-(Methacryloyloxy) ethyltrimethylammonium chloride (DMC) and methyl allyl polyethenoxy ether (TPEG). The characteristics of AIDA were verified by FTIR and 1 HNMR. In addition, the performances of AIDA in cement slurry including thickening time, compressive strength developments, and adaptability to long standing cementing with lager temperature differences were investigated. The results indicated that AIDA possessed excellent temperature-resistance (180 °C) and good adaptability to long standing cementing with larger temperature differences of 90 °C. Finally, the retarding mechanism of AIDA was revealed through transverse relaxation time (T 2 ) distribution, XRD tests, and adsorption behavior of AIDA on cement particles. The results demonstrated that the stronger retarding effect of AIDA originated from the dual adsorption of AIDA on cement particles compared with AMPS-IA copolymer (PAI). AIDA outperformed PAI in its adaptability to long-term cementing, which was responsible to (a): the adsorbed amount of AIDA at higher temperature is higher than that of lower temperatures, therefore, AIDA has a stronger retarding effect at higher temperature and weaker retarding effect at lower temperature. (b) Compared to PAI, the adsorption strength of AIDA is weaker and easy to de-adsorb, so both the retarding effect and the hydration reaction of cement are realized. Thus, the super-retarding phenomenon of cement slurry containing AIDA is effectively prevented.
研究领域:
材料科学
·
化学工程
✓ 已验证
DOI
JOURNAL OF MATERIALS IN CIVIL ENGINEERING
·
2025
·Vol. 37
·期 5
·04025108
·
IF 3
Fangfang Zhi,Xiaodan Tang,Liang Wang,Zhipeng Bai,Binbin Na,Lei Zhang,Guohui Yang,Linhua Jiang
Cellulose ethers (CE) are generally used in cement-based materials as viscosity modifying admixtures. However, previous investigations scarcely focused on the effect of CE on the carbonation behavior of host materials. This work studied the effect of CE on the carbonation behavior of cement pastes. The carbonation resistance of samples was determined using the carbonation depth and pH values. The changes in hydration products and microstructure of host materials were monitored to reveal the underlying mechanisms using electrochemical impedance spectroscopy, X-ray diffraction analysis, thermogravimetric analysis, scanning electron microscopy, and mercury intrusion porosimetry. The results indicate that CE decrease the portlandite (CH) content and inhibit the growth of CH crystal with a smaller size and eroded edges, thus increasing its reactivity with CO2 during carbonation. CE increase the porosity and coarsen the pore structure because of the air-entrainment effect in cement pastes, promoting the CO2 diffusion in the system. As a result, CE decrease the carbonation resistance of cement pastes with increasing the CE content.
研究领域:
建筑材料学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
CEMENT AND CONCRETE RESEARCH
·
2024
·
IF 10.9
Zhaoyang Sun,Yuyang Zhao,Dongshuai Hou,Zongjin Li,Binmeng Chen
Rheology control is the most critical determinant of success in 3D concrete printing (3DCP), typically achieved through the hydration control of cement. However, this inevitably leads to overdesign of printed concrete featuring a low water-to-binder ratio (w/b), which is incompatible with its non-load bearing purpose and raises a series of environmental and durability problems, such as high carbon footprint and early-age shrinkage. Herein, we propose a novel rheology control strategy via in-situ polymerization, allowing the mix design of printed concrete with a high w/b ratio of 0.6. The proposed approach consists of two stages: 1) introducing monomers as retarders to extend the open time during pumping, and 2) incorporating initiators into the mixture to trigger polymerization, facilitating the structural build-up after deposition by forming polymer bridges between cement particles. We show that the addition of monomers significantly retards yield stress growth, while the following in-situ polymerization engenders a rapid strength development, satisfying the rheological requirements for 3DCP. Mechanistic experiments reveal that the retarding effect results from the complexation of monomers with aqueous species, such as Ca 2+ ions, thereby hindering the nucleation of hydrates. As polymerization initiates, the impetus for the structural build-up of the cement pastes first originates from the proliferation of polymer bridges due to the gradual formation and adsorption of polymer, and then relies on the reinforcement of these polymer bridges through the formation of chemical bonds or crosslinks. On top of the environmental benefit, the proposed strategy holds the potential in avoiding admixtures conflict, mitigating early-age shrinkage, and improving mechanical properties. Our strategy opens possibilities for a novel technical route to achieve rheology control of 3DCP, and the discovery in this work will be a landmark for revealing the mechanism of 3DCP via in-situ polymerization.
研究领域:
土木工程
·
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
MATERIALS & DESIGN
·
2025
·
IF 7.9
Zhaoyang Sun,Ming Sun,Dongshuai Hou,Binmeng Chen
Conventional concrete is generally unsuitable for underwater construction, typically requiring the addition of anti-washout admixtures (AWAs) to improve its washout resistance. Herein, we demonstrate the enhancement of cement paste washout resistance through the in-situ polymerization of acrylamide (AM) and sodium acrylate (SA) and elucidate the underlying mechanisms. Macroscopic experiments reveal a significant improvement, with washout loss reduced to 12 % and 2 % of that observed in REF at 60 min for cement pastes modified by the in-situ polymerization of AM and SA, respectively. This enhancement is attributed to the formation of a more flocculated microstructure, where smaller flocs agglomerate into larger ones due to increased floc strength induced by the bridging effect of the resultant polymers. Consequently, flocs in cement pastes with in-situ polymerized SA exhibit higher strength and a denser structure, with a fractal dimension ( D f ) exceeding 2.00, shifting the floc break mode from surface erosion to large-scale fragmentation and thereby improving washout resistance. Nevertheless, the in-situ polymerization of both AM and SA retards cement hydration, albeit through distinct mechanisms: the non-adsorbing PAM molecules primarily hinder the nucleation and formation of hydration products, whereas the adsorbed PAAS molecules predominantly inhibit the dissolution of aqueous species.
研究领域:
土木工程
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
CONSTRUCTION AND BUILDING MATERIALS
·
2022
·
IF 7.693
Aoao Zhu,Xin Zhang,Rongwei Yang,Changlong Wang
In saline soil or salt lake regions, cement-based materials suffer from combined action of salt attack (SA), carbonation , and cyclic wetting–drying (CWD), and its deterioration mechanism remains an open question. Taking advantage of multiple techniques, this study is dedicated to unveiling the deterioration mechanism of hardened cement paste (HCP) exposed to combined action of SA (sulfate salt or sulfate–chloride salt), carbonation (natural carbonation, 0.035 vol.% CO 2 or accelerated carbonation , 20 vol.% CO 2 ) and CWD. The results show that, when exposed to combined action of SA, carbonation and CWD, HCP exhibits distinct deterioration mechanisms depending on the concentration of carbon dioxide: chemical sulfate attack (i.e., formation of ettringite and gypsum) is mainly responsible for the deterioration of HCP in the case of natural carbonation, whereas decomposition of C-S-H and formation of gypsum are both responsible for the deterioration of HCP in the case of accelerated carbonation. The presence of sodium chloride in sulfate–chloride solution inhibits the sulfate attack as well as carbonation attack of HCP.
研究领域:
土木工程
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
ADVANCED POWDER TECHNOLOGY
·
2024
·
IF 4.2
Jianan Guan,Xiao Liu,Shaojing Liu,Ruijun Gao,Ziming Wang,Suping Cui
A novel dispersant with ionic side chains (ISC-PCE) for cement slurries was elaborately designed and prepared by a simple two-step method and its molecular structure was proved. The performance test results showed that the cement paste containing ISC-PCE exhibited stronger fluidity retention (about 79.6 % after 3 h), longer free settling time (more than 3 h) and fewer flocculating structures, which presented significant dispersing stability. Furthermore, the working mechanism of ISC-PCE to cement particles was also probed via molecular conformation, adsorption, complexation ability, zeta potential and adsorbed layer measurements. It is interesting that the introduction of ionic side chains into conventional dispersant-polycarboxylate superplasticizer (PCE) molecules can achieve gentle and continuous adsorption and increase the adsorbed layer thickness (increased by 103.1 % compared to conventional PCE). The aim of this study is to offer a promising pathway to synthesize a novel PCE endowing outstanding workability stability and great rheological improvements to cement pastes by innovative molecular design. This PCE with ionic side chains has enormous promises as an effective substitute to conventional PCE with nonionic side chains, particularly in the cement paste systems with strict requirements on slump retention.
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
CONSTRUCTION AND BUILDING MATERIALS
·
2025
·
IF 8
Dawei Sun,Wenjuan Li,Jiaxin Wang,Maoshuo Li,Wenxu Ma,Zhen Chen,Xiaoyu Ma,Yali Wang,Jinliang An,Xiaming Feng,Suping Cui
The isocyanate system could directly react with water in the air to cure without adding curing agent, thus realizing self-healing, but it also limited its water resistance in humid environment. In this study, polydopamine was deposited on the surface of isocyanate microcapsules to improve their water resistance. Final microcapsules had a diameter of 322.1 ± 69.8 μm, a shell thickness of 6.5 ± 0.3 μm and a core content of 83.3 % ± 2.4 wt%. The optimum synthesis parameters for polydopamine doposition was dopamine concentration of 8.0 mg/ml, agitation rate of 300 rpm, and reaction duration of 24 h. After being immersed in ambient water for 28 days, the redisual core material of final microcapsules still remained at 15.0 wt%. Besides, the final microcapsules started to decompose at 240.0°C, indicating good thermal stability. The study also investigated the influence mechanism of microcapsules strength and interfacial strength on the mechanical properties of self-healing cement paste. At the same time, the total porosity of self-healing cement paste increased under higher microcapsule concentration. In addition, the self-healing cement paste could effectively repair cracks with width of about 100μm, showed good self-healing ability.
研究领域:
材料科学
·
土木工程
✓ 已验证
产品关联
DOI
高影响因子
Applied Nanoscience
·
2019
·Vol. 10
·期 3
·775-786
·
IF 3.198
Jiang Jun,Hou Li,Lu Zhongyuan,Li Jun,Wang Jinxin,Yang Ying,Niu Yunhui
Nanosilica-modified swelled bentonite used as a pore-forming agent was introduced into cement pastes for the preparation of nanopore-rich lightweight cement pastes (NLCPs). The effect of nanosilica on the pore structure and hardened properties of NLCPs and their influence mechanisms were investigated. The results indicated that the introduction of nanosilica reduced pore size and improved nanopore content, due to increased platelets in voids, voids filled by hydration products and unreacted nanosilica. The percentage of nanopore content improved from 67.2 to 94.7% and 55.5–71.3% after, respectively, introducing a 60% and 80% bentonite slurry with increasing nanosilica replacement from 0 to 20%, and the median pore size decreased from 48.6 to 30.9 nm and 80.4–47.5 nm, respectively. The thermal insulation performance and compressive strength of NLCP were gradually enhanced by adding nanosilica from 0 to 20%. When nanosilica content was 20%, an increasing rate of 55.2% and 220.0% in 7-day compressive strength and 65.3% and 211.1% in 28-day compressive strength, with a 20.7% and 10.5% reduction in thermal conductivity at porosity of 61.3% and 72.3% can be achieved, respectively.
研究领域:
材料科学
·
土木工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF DISPERSION SCIENCE AND TECHNOLOGY
·
2023
·
IF 2.2
Bin Li,Ling Wang
In this study, β-Cyclodextrin (β-CD) as the terminal group was grafted on polyoxyethylene (PEO) via click reaction for preparing monovinyl β-Cyclodextrin monomer (β-P). Then β-P was employed to synthesize a polycarboxylate superplasticizer with β-CD grafted on the side chain [PAA-g-(β-P)nHPEG]. The functional groups, molecular weights, and molecular weight distributions of synthesized copolymers PAA-g-(β-P)nHPEG were characterized by Fourier transform infrared spectra (FT-IR), 1H nuclear magnetic resonance spectroscopy (1H NMR), and gel permeation chromatography (GPC). The dispersion performance of PAA-g-(β-P)nHPEG in cement paste containing montmorillonite (MMT) clay was tested. Sorption measurement and X-ray diffraction (XRD) analysis revealed that the PAA-g-(β-P)nHPEG intercalated less into the interlayer space of MMT than PAA-g-HPEG only with PEO as the side chain. β-CD as the terminal group grafted on the end of the side chain of PCE effectively hindered PCE sorption on MMT and enhanced the clay-tolerance property of PAA-g-(β-P)nHPEG. This study offered a new idea in designing polycarboxylate superplasticizers to lower their clay sensitivity.
研究领域:
材料科学
·
土木工程
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）