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HPEG 2400 (Methyl Allyl Alcohol Polyoxyethylene Ether,CAS No.31497-33-3)is a key macromonomer for polycarboxylate superplasticizer (PCE)and one of the most widely used type C4 polyether monomers in the field of concrete admixtures.Its molecular weight is precisely controlled at 2400±100 ,and its molecular structure combines reactive double bonds with long-chain polyoxyethylene ether side chains;through copolymerization with acrylic acid and other monomers to form a comb-like structure,it endows polycarboxylate water reducers with core properties of high water reduction,high slump retention and high strength enhancement.
As a key raw material for concrete engineering,the performance of HPEG-2400 directly determines the quality of water reducers,and it is widely used in high-speed railways,bridges,water conservancy and other high-end projects,making it an
indispensable basic material for modern high-performance concrete.
HPEG-2400 ,fully known as Methyl Allyl Alcohol Polyethylene Glycol Ether,is a special polyether monomer for PCE ,named after its molecular weight of 2400.It is a polymer compound produced by the addition polymerization of methyl allyl alcohol and ethylene oxide,serving as the core raw material for synthesizing polycarboxylate-based high-efficiency water reducers.
Different from other polyether monomers such as TPEG and APEG ,HPEG 2400 is characterized by high slump retention,high water reduction rate and high reactivity.
Its molecular structure is CH₂=C(CH₃)CH₂O(CH₂CH₂O)ₙ H (n≈54 ,corresponding to a molecular weight of 2400),and this structural feature determines its core functions: the methyl allyl group at one end of the molecule provides unsaturated double bonds, which can undergo free radical copolymerization with monomers such as acrylic acid and methacrylic acid to form the main chain skeleton of polycarboxylate water reducers;the long-chain polyoxyethylene ether provides strong hydrophilicity and steric hindrance effect ,and after being adsorbed on the surface of cement particles, it efficiently disperses cement particles through dual effects of electrostatic repulsion and steric hindrance,preventing particle agglomeration,thereby greatly improving the fluidity and slump retention of concrete.
This comb-like structure of “main chain +side chain”is the core reason why polycarboxylate water reducers synthesized from HPEG 2400 are superior to traditional naphthalene-based and aliphatic water reducers,featuring lower dosage, higher water reduction rate,less slump loss,and better concrete strength and durability.
The performance parameters of HPEG-2400 must strictly comply with JC/T 2033- 2018 “Polyether Monomers for Polycarboxylate Water Reducers”and enterprise internal control standards,with authoritative test data from the enterprise standards of leading manufacturers.
Under the condition of 25℃,the appearance of HPEG-2400 is white to light yellow flaky or blocky solid,and the typical actual measured value is white flaky solid,which is detected by visual inspection;its molecular weight is controlled at 2400±100 ,with a typical actual measured value of 2380-2420 ,detected by GPC gel permeation chromatography;the hydroxyl value is 21.4-25.4 mgKOH/g according to the standard requirement ,and the typical actual measured value is 23.0-24.0 mgKOH/g, tested in accordance with GB/T 7383-2007.
The double bond retention rate is not less than 92.0%as required,and the typical actual measured value is 95.0-99.0%, detected by iodometric method ;the pH value of 1%aqueous solution is 5.5-8.5 ,with a typical actual measured value of 6.5-7.5 , measured by pH meter;the moisture content is not more than 0.60%,and the typical actual measured value is 0.20-0.40%,tested by Karl Fischer method ;the chroma (Pt Co,25%aqueous solution)is not more than 30 ,with a typical actual measured value of 15-25 ,detected by colorimetry;it is easily soluble in water,and the actual measured performance is completely soluble without precipitation,verified bydissolution test.
The value of HPEG-2400 is ultimately reflected in the performance of the synthesized polycarboxylate water reducer;tested in accordance with GB/T 8076-2025 “Concrete Admixtures”(to be implemented in August 2026),the typical performance is as follows:for the water reducer mother liquor with a solid content of 20%,when the dosage is 1.0%(cementitious material dosage),the water reduction rate reaches 30%-35%,far exceeding that of traditional naphthalene-based water reducers (18%-
25%).
For concrete,the initial slump is 220±20mm ,and the slump loss after 1 hour is not more than 30mm,which is much better than that of ordinary polyether monomers (loss ≥50mm);in terms of strength enhancement effect ,the 3-day compressive
strength ratio of concrete is not less than 140%,7-day not less than 150%,and 28-day not less than 130%,which significantly improves the early and late strength of concrete;in terms of environmental protection,it is formaldehyde-free,with low
chloride ion (≤0.02%)and low alkali content ,complying with the requirements of GB46039-2025 “Safety Technical Specification for Concrete Admixtures”.
The key parameters for quality control of HPEG-2400 include double bond retention rate,hydroxyl value and moisture content:the double bond retention rate is a core indicator determining copolymerization reactivity,with not less than 95%as premium grade,ensuring that the conversion rate of water reducer synthesis is not less than 98%;the hydroxyl value reflects the length of the polyoxyethylene chain,and the optimal range is 23.0±1 .0 mgKOH/g,which directly affects the balance between water reduction rate and slump retention;the moisture content should be ≤0.5% to avoid affecting reaction stability and product shelf life.
The core use of HPEG-2400 is to synthesize polycarboxylate-based high performance water reducers (PCE),and it can also be adapted to different concrete scenarios through modification to extend a variety of segmented applications.The most important application of HPEG-2400 is the production of standard polycarboxylate water reducers,accounting for more than 70%of the total dosage.
By copolymerizing with acrylic acid,acrylate and other monomers in proportion,it synthesizes general-purpose polycarboxylate water reducers,which are suitable for most conventional concrete projects,balancing water reduction,slump retention and strength enhancement performance with the highest cost performance.
Thanks to the excellent steric hindrance effect of its long polyoxyethylene chain, HPEG 2400 is also specially used to produce high slump-retention polycarboxylate water reducers,solving the problem of slump loss in ready-mixed concrete during long-distance transportation and high-temperature construction,and it is widely used in ready-mixed concrete and long-distance pumping projects.
By adjusting the ratio of HPEG-2400 to other monomers,it can synthesize early strength polycarboxylate water reducers,accelerate cement hydration reaction,and improve the early strength of concrete (1-day and 3-day strength),which is suitable for precast components,winter construction and rapid formwork removal projects.
HPEG-2400 can also be adapted to special concrete scenarios:for mass concrete,it synthesizes low hydration heat type water reducers,reduces the internal temperature rise of concrete,avoids temperature cracks,and is applied to water conservancy dams and nuclear power projects.
For self-compacting concrete,it synthesizes high flow type water reducers,which can self-level and compact without vibration,suitable for complex structures and dense reinforcement projects;for high-strength concrete (C60-C100),the high water reduction rate can greatly reduce the water-binder ratio (≤0.25),prepare ultra-high-strength concrete,and apply to super high-rise buildings and cross-sea bridges.A small amount of HPEG-2400 can also be used in fields such as cement grinding aids,ceramic dispersants and water-based paint dispersants,using its high water solubility and dispersibility to improve productprocessing performance.
For storage requirements,HPEG-2400 should be hermetically stored in a dry, ventilated and cool place,with the temperature controlled at 5-35℃,avoiding direct sunlight,rain and moisture;moisture-proof is the core,and excessive moisture will lead to product caking and decreased double bond retention rate,affecting the quality of water reducer synthesis;the shelf life is 12 months,and after the shelf life, the double bond retention rate and hydroxyl value need to be re-detected before use.
For transportation requirements,it is packaged in 25kg/bag (kraft paper bag +inner PE film)or 220kg/barrel,which is an ordinary chemical product,not a dangerous good; during transportation,avoid collision and extrusion to prevent packaging damage,and keep away from heat sources and fire sources.
For usage notes,when synthesizing water reducers,strictly control the double bond retention rate and hydroxyl value of HPEG 2400 to ensure the reaction conversion rate;the performance of HPEG 2400 from different manufacturers is slightly different , so a small test is required before use to adjust the synthesis formula;during concrete construction,adjust the dosage of water reducer (0 .8%-1 .2%)according to engineering needs to avoid segregation and bleeding caused by excessive dosage.
HPEG-2400 is the core cornerstone of polycarboxylate-based high-performance water reducers.Its precise molecular weight,excellent structural design and stable performance determine the quality of modern high-performance concrete.
With the core advantages of high water reduction rate,high slump retention,high enhancement and environmental protection,HPEG-2400 has become the preferred polyether monomer for high-end projects such as high-speed railways, bridges, water conservancy and super high-rises, with a market share of more than 60%.
With the implementation of the new GB/T 8076-2025 standard and the growth of demand for high-performance concrete,the technological iteration and quality upgrading of HPEG-2400 will continue to advance.In the future,it will further develop towards low viscosity,high activity and customization,providing core support for the greenization and high performance of concrete projects.
