The average grain diameter of red mud is even smaller than that of micro-cement (4 6 μm).
The concrete mix used in the experiments consists of crushed gravel, micro silica, plasticizer, cement, and water.
Several factors induce the difference: for example, it takes some time for equipments to reach high power, some areas of formation are not completely saturated, micro-fractures in formation exist and there are micro-gaps between cement casing and wellbore.
To clarify the effects of supplementary cementitious materials (SCMs) on the mechanical properties of cement-based materials, micro-structurally designed cement pastes, which were prepared by adding mono-sized SCMs into ultrafine Portland cement, were subjected to compressive strength tests.
In addition, the analysis of XRD, FT-IR, Nitrogen-absorption test and SEM revealed the hydration mechanism and the connection between macroscopic and micro-mechanism of cement paste incorporating different dosages silicane.
At the micro-scale, the cement paste and the ITZ can be assumed to be composed of intrinsic cement paste phase and the pore-water inclusion, with different porosities.
By changing the type, the addition and the size of SCMs in the micro-structurally designed cement pastes, effects of SCMs particles on the compressive strengths of cement pastes were quantitatively characterized, and then classified into inherent characteristic effect, particle size refinement effect, and hydration effect.
On the other hand, repeated micromotions in the matt finished rough stem could cause micro-fracture of cement and cement debris, and produce a passage for wear particles down to the femoral canal (Crawford et al. 1999, Howell et al. 2004).
The development of micro-annulus and micro-cracks within the cement sheath causes the need to develop a unique self-healing spacer fluid to enhance the integrity of cement sheath.
Experiment results indicated that the novel self-healing spacer fluid could penetrate into the micro-cracks or micro-annulus within the cement sheath to activate the hydration reaction of the non-hydrated cement, thereby producing a hydrated calcium silicate gel (C S H or C A H) that could strengthen the main body for the damaged zone.
PFRC under impact loading has more micro cracks, while plain cement specimen shows brittle failure.
