95% Undensified Silica Fume
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Undensified Silica Fume
95% Undensified Silica Fume
As-produced microsilica for high-strength concrete, hydraulic works and refractories
95% undensified silica fume - also known as microsilica, silica dust or condensed silica fume - is a grey, amorphous SiO₂ powder with >95% SiO₂ content and a bulk density of 240-320 kg/m3. It is recovered as a by-product of silicon metal and ferrosilicon production; Ewende also provides 95% Densified Silica Fume for your choice.
Sichuan Ewende New Material Co., Ltd.
85 - 99.99 grade silica fume · Made in ChinaWhat it does for your mix
Six reasons engineers specify 95% undensified microsilica - from the way the particles are formed to the grade range Ewende can produce.
95% SiO₂, grey powder
A micro-silica fume with 95% SiO₂ content and a bulk density of 240-320 kg/m3, supplied as a grey amorphous powder - no fillers, no blending.
Recovered from silicon metal furnaces
Silica fume is a by-product of producing silicon metal or ferrosilicon alloys, and consists primarily of amorphous silicon dioxide (SiO₂) condensed from the furnace off-gas.
Unrivaled strength amplification
Significantly increases the compressive and flexural strength of concrete mixes - the ingredient behind high-strength structures that withstand heavy loads and environmental pressures.
Densification and impermeability
The unique particle size distribution fills the voids in the mix, blocking water, chemicals and corrosive agents - longer-lasting structures with lower maintenance requirements.
Enhanced durability
Improves resistance to abrasion, freeze-thaw cycles and other deteriorating factors, keeping structures solid over time and reducing the need for frequent repairs.
Eco-conscious solution
Cuts the need for clinker production in cement and curbs carbon emissions - a greener way to build that still delivers exceptional performance.
95% Undensified Silica Fume parameters
Produced in conformance with ASTM specifications. Quality is controlled and monitored through the entire production process to ensure it meets or exceeds specification requirements.
| SiO₂ content | >95%Minimum per grade · ASTM C1240 / EN 13263 require ≥ 85% |
|---|---|
| Form | UndensifiedAmorphous sub-micron powder · densified 95D also available |
| Bulk density | 240-270 kg/m3 · 320 kg/m3As-produced band · grade intro quotes 240-320 kg/m3 |
| Specific gravity | Reported on COAInsoluble in water |
| pH value | 5 - 8.5 |
| Colour | Grey |
| Loss on ignition | Reported on COAASTM C1240 limit ≤ 6% |
| Moisture content | Reported on COAASTM C1240 limit ≤ 3% |
| 45 μm sieve residue | Reported on COAASTM C1240 / CSA A23.5 limit ≤ 10% |
| Pozzolanic activity index, 7 d | Reported on COAASTM C1240 limit ≥ 105% |
| Specific surface area | Reported on COANational standards require ≥15 m2/g |
| Standards compliance | ASTM C1240 · EN 13263 · GB/T 18736 · GB/T 27690COA |
View the full comparison - silica fume limits under 9 national standards
| Parameter | EuropeEN 13263 | NorwayNS 3045 | FranceNF P18-502 | AustraliaAS 3586 | United StatesASTM C1240 | CanadaCSA A23.5 | JapanJIS A6207 | ChinaGB/T 18736 | ChinaGB/T 27690 |
|---|---|---|---|---|---|---|---|---|---|
| SiO₂ (%) ≥ | 85 | 85 | 85 | 85 | 85 | 85 | 85 | 85 | 85 |
| SO₃ (%) < | 2 | - | 2.5 | 3 | - | 1 | 3 | - | - |
| Cl⁻ (%) < | 0.3 | Report | 0.2 | Report | - | - | 0.1 | 0.1 | 0.1 |
| CaO (%) < | 1 | 2 | - | - | - | - | 1 | - | - |
| MgO (%) < | - | - | - | - | - | - | 5 | - | - |
| Si (%) < | 0.4 | - | - | - | - | - | 0.4 | - | - |
| Na₂O + K₂O (%) < | - | - | 4 | - | - | - | - | - | 1.5 |
| C (%) < | - | - | 4 | - | - | - | - | - | - |
| Moisture content (%) < | - | - | - | 2 | 3 | - | 3 | 3 | 3 |
| Loss on ignition (%) < | 4 | 5 | - | 6 | 6 | 6 | 5 | 6 | 4 |
| Specific surface area (m2/g) | 15-35 | ≥12 | 20-35 | - | - | - | ≥15 | ≥15 | ≥15 |
| 45 μm sieve residue (%) < | - | - | - | - | 10 | 10 | - | 5 | - |
| Bulk density (kg/m3) | - | - | - | Report | Report | - | - | - | - |
| Specific gravity (g/cm3) | - | - | 2.1-2.3 | - | - | - | Report | - | - |
| Water demand ratio (%) ≤ | - | - | - | - | - | - | - | 125 | 125 |
| Pozzolanic activity index, 3 d (%) ≥ | - | - | - | - | - | - | - | - | - |
| Pozzolanic activity index, 7 d (%) ≥ | - | - | - | Report | 105 | 85 | 85 | 95 | 105 |
| Pozzolanic activity index, 28 d (%) ≥ | 100 | 95 | - | - | - | - | 100 | 115 | - |
| Water / binder ratio | 0.5 | 0.5 | - | - | 0.484 | - | 0.5 | 0.5 | 0.5 |
| Curing regime | Standard | Standard | - | - | Accelerated | Accelerated | Standard | Standard | Accelerated |
Limits shown are the specification requirements of each national standard, for reference only. Actual values for each shipment are reported on the Certificate of Analysis.
How to dose it on site
Five practical notes that decide whether 95% undensified microsilica performs - dosage band, admixture pairing, mixing time and curing.
-
1
In high-strength, high abrasion resistance and anti-washout underwater concrete, the dosage should not be too low - usually 5%-10% of the cementitious material.
-
2
Preparing high-strength or early-strength concrete with Ewende 95% undensified silica fume calls for a high-efficiency water reducing agent; for high-strength concrete choose a low-air-entraining type, and add a defoamer where the situation calls for it.
-
3
In ordinary strength, impermeable, highly durable or self-compacting concrete, a multi-component cementitious material with a lower dosage is appropriate - usually 2%-5% of the cementitious material.
-
4
Adding 95% undensified silica fume needs a longer mixing time, and it must not be added to concrete that has already been wetted. Extend mixing by about 30 seconds versus ordinary concrete to ensure uniform dispersion.
-
5
The mix is sensitive to plastic shrinkage cracking. Spray a curing agent on shotcrete before it sets; once the concrete has hardened, use curing film and cover with wet sacks or plastic sheet.
Where 95% undensified microsilica is used
From shotcrete and refractories to oil-well cement - the same pozzolanic reaction, solving very different problems on site.
Shotcrete
High resistivity and low permeability cut chloride corrosion of rebar and mesh, reduce rebound and improve freeze-thaw durability.
Refractories
Works as binder, active agent and mineralizer - improves solid-phase reaction, sintering density and crystal transformation.
Insulation material
The main raw material for composite silicate thermal insulation coatings and boards.
Raw concrete
Reduces surface air bubbles, lifts surface strength, smooths the finish and inhibits carbonation.
Oil well cement
Improves thermal stability, changes the C/S ratio and yields hydration products with high strength and low permeability.
Packaging
Palletized Small Bags
25kg soluble paper bags, 42 per pallet - space-saving, forklift-friendly and fast to load into containers.
Palletized & Stretch-Wrapped
Pallets secured with stretch film for safe loading, unloading and long-distance ocean shipping.
Kraft Paper Bags
25kg moisture-proof kraft paper bags with inner PE liner - easy to carry, ideal for construction sites.
Jumbo Bags (FIBC)
500-1000kg plastic woven bags, 2 per pallet, with or without bottom discharge spout - built for bulk handling.
Custom Logo Packaging
Your own logo, bag design and marking - professional OEM service to build your brand worldwide.
Contact Us
GET A QUOTECall Us
+86 13109355617Email Address
ewende@microsilica-si.comFAQ about 95% undensified silica fume
Ewende's mission is to provide professional services, high quality products and strict after-sales control - and to actively solve customer problems for mutual benefit.
Are you a factory or a middleman?
Ewende New Materials Co., Ltd. is a professional manufacturer and supplier of micro silica powder, with a variety of submerged arc furnace types.
Undensified vs densified - what is the difference?
95U is collected straight from the furnace and never compacted, so every particle stays fully dispersed and it wets out fastest in the mixer - at a loose bulk density of 240-320 kg/m3. Densified grades such as 95D are compacted for easier storage and transport.
How long will delivery take?
Usually around 15 days after order confirmation or deposit.
What are the payment terms?
TT, L/C and D/P; Paypal is also available.
What is your MOQ?
Usually 10 tonnes to start.
Can you offer samples and print our brand on the packing?
Samples are free in testing quantity; we offer neutral packing, and logo spraying on the outer packaging can be negotiated according to the actual quantity.
GET A QUOTE
All-Grade Price List, Within 24 Hours
One form, twelve grades. A sales engineer replies with the full FOB price list + freight to your port — or just the grades you mark.
- ✔Full 12-grade price list as PDF
- ✔Free samples of the grades you shortlist
- ✔Engineer helps you pick if you're between grades