Nano cements
Nanocements present revolution in construction sector, revising existing standards of high-quality cements and concretes. This is quantum breakthrough in concrete technology; their application can effectively engage local, sub-standard to the existing standards small and large aggregates, radically accelerate hardening of concrete, give up energy intensive steaming, produce concrete of HPC class and the products on their basis at a lower cost of labor; improve technological level of all areas of concrete utility, simplify the technology
of formation of products and constructions using modern achievements of non-frame molding.
Fig. 1 Effect of mechanoactivation and nanoencapsulation
It is a radical shift in the principal indicator of cement quality – the strength of its concrete. Nanocements are produced with addition of more than 65% of mineral supplements, such as sand, ash, slag, tuff, etc.
Capsules of nanocement are created by mechanical activation of cement dispersion formed as composites, which consist of nuclear particles of cement, ranging in size up to 2-3 mkm and coated with thin membranes (thickness is in the range of 10-100 nm) of modification material.
Constructional and technical properties of mechanically activated cements provide the possibility to produce on their basis high-strength concretes of 500–800 brands and heavy-duty concretes of 1300–1500 brands, a wide range of concrete products without the use of steaming. They are fast hardening, waterproof, etc. Nanoencapsulation helps to produce high quality cements with no expiration date.
It is a radical shift in the principal indicator of cement quality – the strength of its concrete. Nanocements are produced with addition of more than 65% of mineral supplements, such as sand, ash, slag, tuff, etc.
Capsules of nanocement are created by mechanical activation of cement dispersion formed as composites, which consist of nuclear particles of cement, ranging in size up to 2-3 mkm and coated with thin membranes (thickness is in the range of 10-100 nm) of modification material.
Constructional and technical properties of mechanically activated cements provide the possibility to produce on their basis high-strength concretes of 500–800 brands and heavy-duty concretes of 1300–1500 brands, a wide range of concrete products without the use of steaming. They are fast hardening, waterproof, etc. Nanoencapsulation helps to produce high quality cements with no expiration date.
Additional factors in the intensive growth of the strength of cement stone
A simplified version of the chemical reactions necessary for the formation of cement stone with indication of initial and final composition of the reagents:
3 CaO SiO2 + 3 H2O + SiO 2 = 2 ( CaO SiO2 H2O) + Ca (OH)2
There are two types of hydrated minerals in the formed cement matrix,
hydrosilicates calcium – 85%
calcium hydroxide – 15%
To improve the strength properties it is desirable to bind calcium hydroxide into more durable and long-lasting hydrated calcium by the reaction:
Са (ОН)2 + SiO2 = CaO SiO2 H2O
Such reaction is secured by the level of dispersion of silica (from several to tens of microns), comparable to the size of cement particles.
Nanocements are drastically different from usual cements in key parameters
Figure 2. Nanocements are drastically different from usual cements in key parameters