Macro-Defect-Free MDF Cement

The intercalation of poly(acrylamide)-montmoriUonite superabsorbing polymer composites (SAPCs) into an aluminate cement matrix leads to a noticeable improvement in the mechanical properties of the hardened cement paste. The addition of as little as 0.6% SAPCs increases the compressive strength from 36.1 to 44.4MPa, the modulus of elashcity from 7.8 to 11.1 GPa, and the split tensile strength from 3.3 to 7.0MPa, for a W/C ratio of 0.4 (Gao et al, 1997). 

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In terms of reinforcement, hydrocalumite/polymer nanocomposites may also be considered as promising in the field of cement-related materials. The so-called macro-defect-free (MDF) cements are based on the filHng by polymer of the macroscopic voids responsible for the breakdown of cement. The hydrocalumite phase is formed during the hydration of cement and is known to readily incorporate polymers between its layers [71-75]. 

Donatello, S., Tyres, M., and Cheeseman, C.R. (2009) Recent developments in macro-defect-free (MDF) cements. Constr. Build. Mater., 23 (5), 1751-1757. 

Macro defect-free (MDF) hydraulic cements with porosities approaching zero can be made from Portland cement or high-alumina cement. These cements are mixed with water-soluble polymers such as polyvinyl alcohol or polyacrylamide before allowing to set [26,27]. Possible analogous... 

While these attempts to optimize the strength and durability of cement were more or less unsystematic and empirical, the exact details of the chemistry of cement were first elucidated by Le ChateHer (1904). Later developments included the invention of reinforced concrete by Wilkinson and Lambot in 1855, and of blast furnace cement by Emil Langen in 1862. Thereafter, the twentieth century witnessed the invention and optimization of sulfate-resistant alumina cements (1908), the addition of plasticizers such as Hgnosulfonic acid or hydroxylated polysaccharides and superplasticizers such as sulfonated naphthalene-formaldehyde condensate, and the advent of macro-defect-free (MDF) and polymer fiber-reinforced cements, to name only a few. 

The tensile strength of Portland cements is limited by the presence of relatively large pores (0.1-1.0 mm). Modern research has produced cements that are substantially free of large pores (macro-defect-free or MDF cements) and have very promising mechanical properties for example, MDF cements can be formed into cement springs.70 d... 

In eighties of twentieth century the two new technologies of very high strength cement pastes were developed the DSP— Densifted Systems containing homogeneously arranged ultra-fine Particles (in Denmark), and the MDF— Macro Defects Free Cements. 

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