Development and application of high-density cement-based materials

Abstract

The properties of cement-based binders change dramatically when ultrafine particles are homogeneously placed in the spaces between densely packed cement grains, the increased density and the refinement of the pore structure of such binders result in considerable increases in properties such as compressive strength, impermeability and adherence to fibres and aggregates. It has been shown that such cement-based binders may be processed by simple techniques, and that the resulting materials may replace metals, ceramics and plastics.

Humidity Dependence of Apparent Dielectric Constant for DSP Cement Materials at High Frequencies

“…Because low strength results from high porosity with larger pore sizes, 1 the main principle in the development work toward increased strength has been to reduce the total porosity of the cement paste by various methods. [1][2][3][4][5][6][7] A new class of materials has been developed that has extremely high compressive strength. The new materials are termed DSP, referring to a densified system containing homogeneously arranged ultrafine particles or, more simply, densified with small particles.…”

“…DSP cement can be used as tool and mold materials. 2 Although the mechanical and electrical properties of hardened cement pastes have been investigated and exploited, there has been little reported on electrical applications. [9][10][11][12][13][14] The dielectric properties for DSP cement have been improved considerably.…”

“…15 In contrast with the ordinary portland-cement-based concretes, a higher resistivity value of 10 6 ⍀⅐cm has been achieved for hardened DSP cement pastes at 100% relative humidity (RH). 2 Leigh et al 9 have reported electrical resistivity, dielectric constant, and dielectric loss (tan ␦) values for DSP cement materials in the frequency range 1 kHz to 10 MHz. A resistivity of 10 11 ⍀⅐cm, dielectric constant of 5, and tan ␦ of 0.01 measured at 1 MHz and 25°C have been achieved for dried and hardened DSP cement material.…”

Crack Growth in Hardened Cement Paste

“…Hot-pressing may be regarded as an example of this, but more interesting are recent developments in which the hydrates are modified by either, the addition of long-chain polymers ["MDF" (Birchall et al, 1981)], or very fine silica [ O.lum-"DSP" (Hjorth, 1983)]. Examination of these materials, particularly crack paths within then, may also provide information on possible mechanisms of inproving the strength of more conventional HCP.…”