Diethanolisopropanolamine (DEIPA) is a tertiary alkanolamine corresponding to CAS 6712-98-7 and chemical name N,N-bis(2-hydroxyethyl)isopropanolamine. The compound is produced by ethoxylation of monoisopropanolamine, yielding a molecule with one tertiary amine centre and three terminal hydroxyl groups. Its molecular formula is C₇H₁₇NO₃, and the calculated molar mass is 163.22 g/mol. Commercial DEIPA is typically supplied as a clear, colourless to pale-yellow hygroscopic liquid with an active assay of 85–90 % as determined by gas chromatography, with the balance consisting of water and low-level residual amines. The product is water-miscible, polar, and alkaline. In cement grinding aid packages, DEIPA is not a direct replacement for triethanolamine (TEA) or triisopropanolamine (TIPA); rather, it is selected as a co-formulant when controlled changes in grinding efficiency, pack-set behaviour, and mortar strength development are required. The molecule differs from methyl diethanolamine (MDEA) and monoethanolamine (MEA) in amine classification, molecular weight, and acid-gas reactivity; these differences are material to both storage design and application dosing.

Certificate-of-analysis data for bulk DEIPA are normally reported against a defined set of wet-chemical and instrumented methods. Water content is measured by coulometric Karl Fischer titration under ISO 760; colour is assessed as platinum-cobalt units under ASTM D1209-05; density is measured at 20 °C under ASTM D4052-22; refractive index is measured at 20 °C under ASTM D1218-21. Purity is typically determined by gas chromatography with flame ionisation detection, using an internal standard; published data for this specific configuration is limited. A representative bulk specification is given in Table 1. The amine value of DEIPA is frequently quoted in procurement specifications, but the number is method-dependent because non-aqueous titration of a tertiary amine must be carried out with a suitable solvent and indicator. Consequently, direct amine-value comparisons between DEIPA and primary or secondary alkanolamines without method qualifiers are not technically valid.

Because DEIPA is hygroscopic, water content can increase by more than 0.2 % in a single open-head transfer if the ambient relative humidity exceeds 60 %. For this reason, bulk storage in nitrogen-blanketed or closed-loop systems is standard for certifications requiring water content below 0.5 %. Typical packaging for DEIPA includes 200 kg high-density polyethylene drums, 1000 kg intermediate bulk containers, and bulk isotainers. For cement grinding aid producers consuming multiple daily tonnes, bulk storage is preferred because drum handling increases moisture uptake and static electricity risks during transfer. Transfer hoses should be chemical-resistant rubber or stainless-steel flex hose; natural rubber and unlined steel are not recommended for continuous exposure because the alkaline product can promote corrosion at the liquid-vapour interface. A closed-loop vapour-return line is recommended when tanker unloading is performed at ambient temperatures above 25 °C.

What Limits DEIPA Dosage in Closed-Circuit Cement Mills?

In closed-circuit cement milling, DEIPA is introduced either onto the clinker feed belt or through a dilute aqueous spray into the first compartment of the mill. The conventional dosage range for pure DEIPA is 0.005–0.02 wt% of cement mass. In a mill operating at 100 t/h clinker feed, a dosage of 0.01 wt% corresponds to 10 kg/h active DEIPA, or approximately 11.8 kg/h of an 85 % active commercial product. The additive is typically diluted with water to 20–40 wt% before injection through a positive-displacement metering pump; this dilution reduces localised amine concentration on hot clinker surfaces and improves dispersibility. The primary process constraint is not solution viscosity but the onset of amine adsorption onto freshly fractured clinker and calcium silicate surfaces, which changes the agglomeration state of the mill charge. Process engineers typically track mill elevator power draw, separator reject mass flow, and Blaine specific surface area against an air-permeability method. A target Blaine fineness of 3200–3800 cm²/g is common for CEM I cements under EN 197-1:2011, but the response to DEIPA is batch-dependent because clinker sulfate balance, free lime, and grinding temperature shift the adsorption equilibrium. Dosing above 0.03 wt% is generally avoided in grinding aid formulations because the resulting cement may exhibit silo flow irregularities and altered pack-set behaviour, particularly when mill outlet temperatures exceed 120 °C. Published data for this specific configuration is limited.

Clinker chemistry and mill conditions affect the response. A high free-lime clinker above 1.5 % by mass may exhibit a different adsorption isotherm for DEIPA than a low-free-lime clinker because the amine can coordinate to calcium-rich surface sites. Similarly, high sulfate clinkers may alter the competitive adsorption of sulfate ions and alkanolamines on C₃A and C₄AF surfaces. A mill trial protocol typically includes a 4-hour baseline period, an 8-hour injection period, and sample collection every 30 minutes for Blaine fineness, 45 µm sieve residue according to EN 196-6:2018, and pack-set index. Mill outlet temperature is usually kept below 120 °C to avoid thermal degradation of the amine and above the dew point to prevent pre-hydration. Inlet moisture above 2 % on clinker feed can reduce grinding aid efficiency because water competes for surface hydroxyl coordination sites. Published data for this specific configuration is limited.

In polycarboxylate ether-based concrete admixture systems, DEIPA is not used as a primary water-reducing agent. It may be present as a minor co-formulant in strength-enhancing or hydration-controlling admixtures. Compatibility is evaluated under ASTM C494/C494M-19 or EN 934-2 as appropriate to the target market, with measurement of setting time, air content, and compressive strength. At equal dosage, DEIPA does not automatically reproduce the early-age set behaviour of TEA; TEA is often associated with accelerated initial hydration at low dosage, while TIPA is more commonly associated with later-age strength effects. DEIPA occupies an intermediate position in molecular weight and hydroxyl value, and its use in commercial admixtures is typically accompanied by comparative mortar testing at 1 day, 7 days, and 28 days according to EN 196-1:2016. A dosage window of 0.005–0.02 wt% by cement mass is common in evaluation studies. Published data for this specific configuration is limited.

Air entrainment is particularly sensitive. Tertiary alkanolamines can change the surface tension of the aqueous phase, altering the bubble-size distribution produced by air-entraining admixtures. Therefore, trial batching under EN 12350-7:2019 or ASTM C231-17 should measure fresh air content and air-void spacing factor, not only compressive strength. A change of 0.5 % in air content can shift freeze-thaw durability classification; this is a critical threshold in external concrete. High C₃A cements above 8 % by mass may require lower total alkanolamine dosage because adverse setting-time changes can overshadow grinding benefits. Published data for this specific configuration is limited.

When DEIPA Replaces TIPA in Cold-Weather Grinding Aid Formulations

TIPA is solid at ambient temperature, with a melting point near 58 °C, and requires heated storage, trace heating, or blend dissolution before use. DEIPA remains liquid at 25 °C, which reduces the need for heated transfer lines and lowers the risk of solidification in unheated dosing cabinets. The comparative molecular and physical data are shown in Table 2. In cold-weather grinding aid formulations, DEIPA can be substituted for part or all of the TIPA fraction to maintain a pumpable, homogeneous liquid blend at temperatures below 10 °C. The substitution ratio is not a simple one-to-one replacement; formulators typically adjust the ratio between 1:3 and 3:1 DEIPA:TIPA based on mill trials. Because DEIPA has a lower calculated hydroxyl value than TEA but a higher calculated hydroxyl value than TIPA, its effect on cement paste fluidity and early hydration must be separated from the effect of the glycol carrier. The grinding aid package may include diethylene glycol, lignosulfonate, sodium acetate, or triethanolamine as secondary components. When DEIPA replaces TIPA, the viscosity of the package may decrease, and the cloud point of the aqueous blend can shift; a storage stability test at 4 °C for 7 days is therefore used to verify that no phase separation or sedimentation occurs. Published data for this specific configuration is limited.

Calculated hydroxyl value is not a direct measure of performance in cementitious systems; it is a structural index. DEIPA has a calculated hydroxyl value of 1031 mg KOH/g, between TEA at 1129 mg KOH/g and TIPA at 880 mg KOH/g. The calculated amine value follows the inverse order: TEA 376 mg KOH/g, DEIPA 344 mg KOH/g, and TIPA 294 mg KOH/g. These values are derived from the molar mass and functional group count, not from titration of commercial blends. Because commercial DEIPA is supplied at 85–90 % assay, a reported amine value on an as-is basis must be corrected for water content to allow comparison with pure-compound data. In procurement of closed-loop grinding aid systems, specification of DEIPA by gas-chromatographic purity is more reproducible than specification by amine value, particularly when the blend contains residual isopropanolamine and ethanolamine impurities.

DEIPA is sometimes confused with diethanolamine (DEA) because of the diethanol fragment in the commercial name. DEA is a secondary alkanolamine with a molar mass of 105.14 g/mol and is used in gas treating and chemical intermediates, whereas DEIPA is a tertiary amine with three hydroxyl groups. In gas-treating evaluations, DEIPA would be expected to have a lower acid-gas reaction rate than primary or secondary amines due to the absence of N–H protons, but published data for this specific configuration is limited. For cement applications, the tertiary structural feature is important because it avoids rapid carbamate formation and may provide a more gradual interaction with clinker surfaces.

Storage, Handling, and Material Incompatibility Boundaries

DEIPA is hygroscopic and mildly alkaline. Bulk storage tanks are typically fabricated from 304 or 316 stainless steel, or from lined carbon steel. Nitrogen blanketing is specified when ambient relative humidity exceeds 60 % because the product can absorb water during open-head transfer. Recommended bulk storage temperature is 10–35 °C; lower temperatures increase viscosity and may require heat tracing, while higher temperatures can accelerate colour development and the formation of trace amine degradation products. The product should not be mixed with strong oxidising agents, acid chlorides, or concentrated mineral acids, because exothermic neutralisation can generate localised boiling and amine decomposition. In grinding aid formulation tanks, DEIPA is routinely blended with glycols, lignosulfonates, and other alkanolamines, but a 14-day stability test at 40 °C is typically applied to detect precipitate formation, phase separation, or viscosity drift. The material should be stored away from direct sunlight and protected from sustained exposure to air. For EU market applications, importers and formulators must verify registration status under REACH Regulation EC No 1907/2006 and provide a safety data sheet with the relevant GHS classification. No summary of the GHS classification is restated here; the safety data sheet of the specific supplier remains the controlling document.

Combination with nitrite-based corrosion inhibitors should be avoided unless the mixture is specifically assessed, because secondary amine impurities can react with nitrosating agents to form N-nitrosamines. For DEIPA, which is tertiary, the risk is lower than for secondary amines, but the presence of residual ethanolamine or isopropanolamine makes nitrite compatibility a formulation constraint. Lot-to-lot variation in DEIPA purity can affect grinding aid performance in production-scale systems. For a bulk tanker receiving 20,000 kg of 85 % DEIPA, a water content shift from 0.3 % to 0.8 % changes the active amine delivered by 100 kg per tanker. Sampling should follow a top, middle, and bottom composite procedure to account for density stratification. Retention samples are typically held at 5–15 °C for 12 months for batch-tracing investigations. Published data for this specific configuration is limited.

A workplace exposure assessment is required when DEIPA is handled in open dosing areas. The amine odour threshold is low, and vapour or mist generation during spray application should be controlled through local exhaust ventilation. Draining of transfer hoses and use of closed-loop sampling stations are common engineering controls on cement grinding aid lines. Waste water containing DEIPA should be assessed for aquatic toxicity and oxygen demand before discharge; disposal must follow national and local regulations for water-miscible alkanolamines. Spill containment capacity should be 110 % of the largest container according to local secondary containment requirements. Published data for this specific configuration is limited.