Geoscience Reference
In-Depth Information
317
318
317
Close view of a white-coloured joint mortar from
Portland limestone masonry, comprising white
Portland cement mixed with finely crushed Portland
limestone particles. Unhydrated white Portland
cement grains are frequently seen (white); PPT, ×300.
318
Close view of a Portland cement-based brickwork
mortar coloured yellow by the addition of pigment
(possibly synthetic yellow iron oxide). The cement
matrix (brown) is seen to enclose a few particles of
pigment (orange-brown, lower right). Fine aggregate
particles appear white; PPT, ×300.
319
319
Unmixed lump of cement (dark brown) within a
Portland cement render. The fine cracks (white) seen
in the cement lump were probably induced by the
oven-drying stage of thin section preparation; PPT,
×35.
320
321
320
Portland cement:sand mortar exhibiting frequent
small, spherical air voids (yellow) indicative of the use
of an agent that has imparted a degree of air
entrainment (i.e. a chemical admixture). Fine
aggregate particles appear white and the cement
matrix is shown brown; PPT, ×35.
321
Weak and friable Portland cement:sand mortar
exhibiting abundant small air voids (yellow), following
overdosing of the mix with water-reducing admixture
(plasticizer). Fine aggregate particles appear white and
the cement matrix is shown brown; PPT, ×35.
