scholarly journals Study on adsorption, rheology and hydration behaviours of Polycarboxylate(PCE) superplasticizer synthesized by different acid to ether ratio

2021 ◽  
Vol 2133 (1) ◽  
pp. 012007
Author(s):  
Zhijun Lin ◽  
Xiaofang Zhang ◽  
Zhanhua Chen ◽  
Yue Xiao ◽  
Yunhui Fang
Keyword(s):  
Molecular Weight ◽  
Adsorption Capacity ◽  
Cement Paste ◽  
Cement Hydration ◽  
Main Chain ◽  
Chain Structure ◽  
Hydration Process ◽  
Side Chain ◽  
Structure Parameters ◽  
Polycarboxylate Superplasticizer

Abstract Polycarboxylate superplasticizer is synthesised by different acid to ether ratio, which is changing the main chain structure parameters, obtained different microstructures. The effect of different microstructure PCE superplasticizer on the fluidity of cement paste, rheological thixotropy, adsorption capacity and hydration heat are studied. The results show that dispersing performance in cement with acid to ether ratio of 3.5 is the best, the molecular weight and side chain density have rather little effect on the cement hydration process.

Effect of Structure of Polycarboxylate Superplasticizer on Hydration of Cement in Early Period

2012 ◽  
Vol 487 ◽  
pp. 24-28
Author(s):  
Jian Ping Duan ◽  
Sheng Hua Lv
Keyword(s):  
Cement Paste ◽  
Setting Time ◽  
Early Period ◽  
The Other ◽  
Side Chain ◽  
Carboxyl Groups ◽  
Structure Parameters ◽  
Polycarboxylate Superplasticizer ◽  
Hydrated Product ◽  
Effect Of Structure

Effect of polycarboxylate superplasticizer (PCs) with different bond between side chain and truck chain on hydration of cement in early period was studied. The performance of PCs in concrete was investigated by setting time, TGA and SEM. PC-based superplasticizer with ester bonding between side chain and truck chain. Although they had the proximate structure parameters in density of side chain and absorption group (carboxyl groups), the setting time of cement paste was significantly different when different PCs were employed in the preparation of cement. Decomposing of this bond in alkali environment may lead to a shorter setting time. On the other hand, same difference in hydration production was observed in early period hydration of cement paste when two different PCs was incorporated, which indicated that the different bond structure in PCs affected the hydration of cement in a different manner. The result of SEM indicated that the morphological phase of hydrated product was different when PC was applied, this may be related with the different result in the TG and TGA

Effects of Molecular Structure of Polycarboxylate Water Reducers on their Performance in Cement Paste

2010 ◽  
Vol 168-170 ◽  
pp. 1854-1858
Author(s):  
Shun Li ◽  
Qi Jun Yu ◽  
Jiang Xiong Wei ◽  
Ya Jun Ji
Keyword(s):  
Molecular Structure ◽  
Molecular Weight ◽  
Induction Period ◽  
Cement Paste ◽  
Cement Hydration ◽  
Side Chain ◽  
Medium Density ◽  
Dormant Period

The polycarboxylate water reducers(PCs) with different molecular structure were synthesized. The effects of molecular structure on their performance in cement paste were investigated. The results show that the PCs with a medium density of PEO side chain and/or a moderate molecular weight and its distribution have a higher dispersibility and a stronger dispersion retention stability at the same time, and that those PCs with a shorter PEO side chain exhibit a stronger dispersion retention stability. The PCs with a higher molecular weight, a lower density and/or a shorter length of PEO side chain are more easy to adsorb on the surface of cement particles. The earlier induction period is shortened while the dormant period is prolonged during the process of cement hydration in the presence of PCs. The PCs with a shorter PEO side chain show a stronger retarding effct. This effect is not very obvious with the decreasing molecular weight.

scholarly journals Effect of nano-SnO2 on early-age hydration of Portland cement paste

2019 ◽  
Vol 11 (6) ◽  
pp. 168781401985194 ◽  
Author(s):  
Jianping Zhu ◽  
Genshen Li ◽  
Ruijie Xia ◽  
Huanhuan Hou ◽  
Haibin Yin ◽  
...  
Keyword(s):  
Portland Cement ◽  
Cement Paste ◽  
Cement Hydration ◽  
Cementitious Materials ◽  
Hydration Process ◽  
Strength Development ◽  
Early Age ◽  
Test Machine ◽  
Portland Cement Paste ◽  
Scanning Electron

Nanomaterial, as a new emerging material in the field of civil engineering, has been widely utilized to enhance the mechanical properties of cementitious material. Nano-SnO2 has presented high hardness characteristics, but there is little study of the application of nano-SnO2 in the cementitious materials. This study mainly investigated the hydration characteristics and strength development of Portland cement paste incorporating nano-SnO2 powders with 0%, 0.08%, and 0.20% dosage. It was found that the early-age compressive strength of cement paste could be greatly improved when nano-SnO2 was incorporated with 0.08% dosage. The hydration process and microstructure were then measured by hydraulic test machine, calorimeter, nanoindentation, X-ray diffraction, scanning electron microscope, and mercury intrusion porosimetry. It was found that the cement hydration process was promoted by the addition of nano-SnO2, and the total amount of heat released from cement hydration is also increased. In addition, the addition of nano-SnO2 can promote the generations of high density C-S-H and reduce the generations of low density C-S-H indicating the nucleation effect of nano-SnO2 in the crystal growth process. The porosity and probable pore diameter of cement paste with 0.08% nano-SnO2 were decreased, and the scanning electron microscopic results also show that the cement paste with 0.08% nano-SnO2 promotes the densification of cement microstructure, which are consistent with the strength performance.

Less Loss of Fluidity of Polycarboxylic Acid Type Water Reducer

2011 ◽  
Vol 71-78 ◽  
pp. 3452-3456
Author(s):  
Xun Zhong
Keyword(s):  
Molecular Weight ◽  
Cement Paste ◽  
Side Chain ◽  
Polycarboxylic Acid ◽  
Acid Type ◽  
Type Water ◽  
Different Molecular Weight

Cement paste and concrete with different molecular weight of side-chain of polycarboxylic acid type water reducer (PC) and retarder has been researched. In this way, the method of adjusting the molecular weight of side-chain and complexing retarder to hold fluidity has been discussed. The results show that with increase molecular weight of side-chain, the dispersibility and holding dispersibility increases. With retarder and PC, the dispersibility and holding dispersibility of PC with big more molecular weight of side-chain increases and the loss of fluidity at 1h prominence reduces. But it relates to breed of cement. Especially at low ratio of water and cement, when molecular weight of side-chain is more than 2000, complexing PC and retarder can improve the fluidity and holding fluidity.

Synthesis, Cement Paste Fluidities and Molecular Weight Measurements of Polycarboxylate Superplasticizer by Bulk Polymerization

2013 ◽  
Vol 405-408 ◽  
pp. 2778-2781
Author(s):  
Xiao Liu ◽  
Zi Ming Wang ◽  
Xu Liang ◽  
Jie Zhu ◽  
Jue Zhao
Keyword(s):  
Molecular Weight ◽  
Polyethylene Glycol ◽  
Solid State ◽  
Maleic Anhydride ◽  
Cement Paste ◽  
Fumaric Acid ◽  
Bulk Polymerization ◽  
Synthesis Process ◽  
The Third ◽  
Polycarboxylate Superplasticizer

The synthesis process of polycarboxylate superplasticizer (PCE) by bulk polymerization was investigated. Compared with BPO as initiator, PCE prepared by using AIBN as initiator exhibited better cement paste fluidities. PCE using isopentenyl polyethylene glycol (TPEG) or isobutenyl polyethylene glycol (IPEG) as macromonomer showed excellent fluidities and retaining properties at 80°C and 75°C, respectively. The fumaric acid was more suitable to copolymerize as the third monomer than maleic anhydride. The molecular weight measurements showed that the characteristics of molecular weight and its distribution for all the synthesized samples were in accordance with their cement paste fluidities. The solid-state PCEs can be conveniently dissolved into water to prepare PCE solution with arbitrary concentration, and still with good cement application performances.

Influence of the side-chain structure and molecular weight on the re-entrant behaviors of mesogen-jacketed liquid crystalline polymers

RSC Advances ◽  
2016 ◽  
Vol 6 (82) ◽  
pp. 78516-78527 ◽  
Author(s):  
Zheng Xiang ◽  
Sheng Chen ◽  
Yongbing Luo ◽  
Ping Li ◽  
Hailiang Zhang
Keyword(s):  
Molecular Weight ◽  
Phase Behavior ◽  
Liquid Crystalline ◽  
Liquid Crystalline Polymers ◽  
Terminal Group ◽  
Chain Structure ◽  
Side Chain ◽  
Spacer Length ◽  
Crystalline Polymers

The influence of the alkyl spacer length and the terminal group volume influence on the phase behavior and structure of mesogen-jacketed liquid-crystalline polymers.

The degradation of solid polymethylmethacrylate by ionizing radiation

1954 ◽  
Vol 223 (1154) ◽  
pp. 392-404 ◽  
Keyword(s):  
Molecular Weight ◽  
Main Chain ◽  
High Energy ◽  
Side Chain ◽  
Radiation Doses ◽  
Cage Effect ◽  
Γ Radiation ◽  
High Energy Radiation ◽  
Direct Dissociation ◽  
Solid Form

When polymethylmethacrylate in the solid form is irradiated in the atomic pile, or with γ-radiation, two reactions predominate: breakdown of the main chain, and decomposition of the side chain with evolution of gases. The former was followed by changes in viscosity, the molecular weight of the irradiated polymer being inversely proportional to the radiation dose (plus a small quantity of R 0 which depends on the initial molecular weight). The degradation is thought to proceed by random rupture of main-chain C— C bonds by rearrangement of the excited polymer, and 61 eV are absorbed per fractured bond. For each main-chain rupture approximately one ester side chain is also decomposed. The cage effect is thought to prevent direct dissociation, and reaction occurs by rearrangement of the molecule to give relatively stable entities. Added substances reduce the amount of degradation, possibly by transfer of energy from the excited polymer molecule. This is only possible if the excited molecules have an appreciable life before decomposition. Viscosity measurements on irradiated polymethylmethacrylate in the solid form offer a possible means of measuring high-energy radiation doses in the range of about 1 million röntgens and upwards.

scholarly journals Effect of Delaminated MXene (Ti3C2) on the Performance of Cement Paste

2019 ◽  
Vol 2019 ◽  
pp. 1-8 ◽  
Author(s):  
Jianping Zhu ◽  
Genshen Li ◽  
Chunhua Feng ◽  
Libo Wang ◽  
Wenyan Zhang
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Cement Paste ◽  
Cement Hydration ◽  
Hydration Heat ◽  
Hydration Process ◽  
Cement Matrix ◽  
Cement Composites ◽  
Hydrated Cement ◽  
Hydration Products

Delaminated MXene was incorporated into cement to improve the properties of cement composites, and its effects on the hydration process, microstructures, and mechanical properties were investigated, respectively. The investigation results showed that delaminated MXene was well-dispersed in the cement matrix and significantly reinforced the compressive strength of cement, especially when the addition is 0.01 wt%. Meanwhile, the total hydration heat of cement hydration and the quantity of hydration products were increased with the addition of delaminated MXene. In addition, the formation of HD C-S-H gel was promoted, and the microstructure of hydrated cement became more compact.

Ultrasonic Monitoring of Hydration Using Embedded Piezoelectric Transducers

2010 ◽  
Vol 177 ◽  
pp. 510-513
Author(s):  
Lei Qin ◽  
Qian Qian Zhong ◽  
Shi Feng Huang ◽  
Xin Cheng
Keyword(s):  
Cement Paste ◽  
Cement Hydration ◽  
Ultrasonic Transducer ◽  
Ultrasonic Waves ◽  
Piezoelectric Transducers ◽  
Hydration Process ◽  
Ultrasonic Monitoring ◽  
Coupling Problem ◽  
Velocity Amplitude ◽  
Wave Parameters

This study utilized embedded piezoelectric transducers for monitoring of cement hydration process. Longitudinal ultrasonic transducer which was suitable for being embedded in cement paste was prepared by cutting PZT rods and coating epoxy layer. The transducers were used to generate and receive ultrasonic waves to continuously observe the hydration of cement paste. The characteristics of wave parameters such as wave velocity, amplitude and frequency were used to interpret the hydration process of cement. Relationship between the character values of the wave and the process of hydration could be established. Therefore, it is feasible to observe the hydration progress using this technology. The coupling problem existed in traditional ultrasonic monitoring of hydration can be solved and the whole life monitoring of cement materials can be also achieved through this method.

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