Industrial Tests of Nanocement Technology
In January 2016, under the agreement between Nanotek Material’s sister organization and a cement production plant in Dubai, test production of Nanocement was carried out on one of the three process lines of the plant in Dubai, UAE. According to the preliminary signed Memorandum between the parties, Nanocement was planned to be produced on an existing process line with a ball mill 4.2 Х 11 m without any changes in the line, with the new technology being ensured by simple feed of the modifier to the ball mill. The plant offered to produce about 600 tons of Nanocement 55 and a small volume of Nanocement 35 on the line.
Process line No. 1 of the Dubai plant included a two-chamber ball mill 4.2 Х 11 m feeding equipment - conveyors, separator and consumable materials bunkers: for clinker - 600 tons, gypsum - 120 tons, mineral additive - 120 tons.
- Ball load: in the first chamber - 90 tons, in the second chamber - 158 tons;
- Line capacity - 75 tons per hour; Standard temperature in the mill – 105 degrees Celsius;
- Reduced pressure at the outlet of the mill - 16 – 20 MPa
The Dubai plant offered sands from two deposits - Al Madam and Ras Al Keima - as the mineral additive. Al Madam sands were delivered to the plant site in the required volume, along with all the other components - clinker for production of class 42.5 Portland cement and gypsum (the one normally used by the plant is rock gypsum and contains about 90% of calcium sulfate dihydrate).
Al Madam desert sand provided by the plant was used in the testing; analysis of its chemical composition and mineralogy using equilibrium kinetic analysis method performed after the testing showed the following contents, mass %: quartz - about 55, calcium carbonate - about 35 and feldspar - about 10
The participating parties in the industrial testing agreed that Nanocement's construction-technical properties test methods will be as per ASTM C157/C1157M-11.
In the course of testing, Nanocement modifier, delivered in 25 kg paper bags from Russia, was used. The modifier was fed manually, directly onto the main conveyor before the funnel inlet of the ball mill in paper bags that were opened from one side.
Nanocement samples were taken every hour at the outlet of the ball mill and sent to the plant laboratory. The commercial testing started at 08:20 with feeding of clinker, desert sand, gypsum and the modifier into the ball mill in the following ratios, mass %: clinker - 55, sand - 39, gypsum - 5, modifier - 1.
The resulting data demonstrate that ball mill operation in terms of its main parameters did not change as compared with the standard mode of operation of the indicated BINANI line. Importantly, feeding a mixture of desert sand together with modifier into the ball mill has positively influenced its operation - increasing tonnes per hour (Table 1).
During the entire period, mill performance improved from the factory basic 75 tons per hour to 85 tons per hour for Nanocement 75 and up to 100 tons per hour for Nanocement 35. Furthermore, the specific surface of Nanocement 55 was more than 400 m2/kg and the specific surface of Nanocement 35 (N-35) increased up to 525 m2/kg (Table 2)
Specification of Dubai Plant's Nanocement Production Line Parameters
Total Nanocement produced - 490.025 tons
- Power consumption- 43.31 kW/ton
- Clinker - 275 tons
- Sand - 190 tons @ 3% humidity
- Gypsum - 25 tons
- Modifier - 5.725
The Dubai test results confirmed the desired qualities of Nanocement. There was substantial improvement of the effectiveness of Portland cement milling in ball mills where in the process of co-milling with the modifier and quartz particles acted as micro-grinding bodies. Thus, facilitating abrasion and preventing aggregation of fine cement particles, while cleaning the grinding bodies and ensuring the improvement of ball mills capacity and, substantial decrease of specific energy consumption.
Construction-Technical Properties of Nanocement 55 Produced at the Dubai Plant and Properties of Concretes on Their Basis
The construction-technical properties of commercial Nanocement 55 were independently assessed and tested at a local laboratory in UAE (Table 4).
Testing of Construction-Technical Properties of Nanocements
Testing of Concretes Based on Nanocement 55 at Safe Mix Facility, Dubai
A commercial batch of Nanocement 55 produced by the Dubai plant was delivered to a safe mix producer in Dubai. Two concrete mixes were prepared based on Nanocement 55 with factory nonmetallic fillers and of composition proposed by the plant. Concrete consistency preservation time and concrete strength within the standard time of hardening were determined (Table 6)
Testing of Concretes Based on Nanocement 55 at Ready Mix Facility, Dubai
Ready Mix is one of the biggest companies in the Middle East and it delivers concretes for construction of high-rise buildings in Dubai and other cities, and, in particular, for construction of Burj Khalifa, the highest building in the world and the main landmark of Dubai and UAE.
Storability of concrete mixes and strength of concretes based on the Dubai tested commercial batch of Nanocement 55
About 200 tons of the tested commercial batch of Nanocement 55 was delivered to the plant. The composition of concrete mix based on Nanocement 55 and nonmetallic feed of the Ready Mix plant was proposed and presented in Table 6. No chemical additives or microsilica were injected into the concrete mix.
As seen from the presented indicators, the Dubai tested commercial batch of Nanocement 55 allowed to produce concrete mixes with good consistency and its preservation in time both in Safe Mix and Ready Mix concrete tests, which is very important in terms of transport conditions and application of concrete in UAE, acountry with a very hot climate.
Composition and properties of concrete mix and concrete based on the Dubai tested commercial batch of Nanocement 55
Our colleagues from Dubai Ready Mix concrete were particularly impressed by the very quick strength development of Nanocement 55-based concrete - in three days the compression strength of the concrete samples reached 45.7 MPa, and in 28 days of normal hardening it reached 72.3 MPa, i.e. concrete of class В 60 was obtained on the basis of nanocement 55 (actual portland cement content in it was 55 mass %, i.e. only 209 kg!). Furthermore, the concrete mix did not contain expensive microsilica that is usually injected in this class of concretes in the amount of 10-15% of cement mass, nor did it include the also expensive chemical additives.