Limestones

Question 1

UK minerals

Answer 1

limestone (industrial/agricultural)
Rock salt
potash
Silica

Question 2

4 groups of limestones

Answer 2

Non-skeletal grains (ooids and peloids)
Skeletal
Micrite
Cement

Question 3

weathering of rocks: soluble products

Answer 3

Ca 2+

HCO 3-

Question 4

Surface seawater supersaturated with

Answer 4

CaCO3

Question 5

Biogenic carbonates

Answer 5

planktonic organims in the water column extract CaCO3 from sea water to build skeletons

Question 6

present day carbonate deposition

Answer 6

95% ocean basins

Question 7

pure carbonate sediment requires absence of

Answer 7

siliclastic material

Question 8

too much siliclastic material will

Answer 8

cloud seawater and reduce sunlight penetration

Question 9

two major controls on carbonate sedimentation

Answer 9

geotectonics

climate

Question 10

modern platform carbonates [2]

Answer 10

Bahama Banks

South Florida Shelf

Question 11

Limestone formation

Answer 11

1. Weathering of rocks to ocean
2. low silica
3. Excretion of skeletal debris
4. Mud and crystals
5. control of geotectonic setting - shallow lagoons

Question 12

three types of British limestones

Answer 12

Carboniferous - Pennines and Peak
Jurassic - less consolidated
Cretaceous - chalk

Question 13

cement ingredients

Answer 13

CaCO3 from limestone or chalk

Silica & Alumina

Question 14

cement processes

Answer 14

+ heat

• CO2
• H20

Question 15

cement clinker [4]

Answer 15

Tricalcium silicate
dicalcium silicate
tricalcium aluminate
tetracalcium aluminferrite

Question 16

cement - metamorphism

Answer 16

cement minerals unstable in the presence of water

Question 17

tricalcium silicate

Answer 17

hydrates rapidly

early and final strength

Question 18

dicalcium silicate

Answer 18

hydrates slowly

strength at later ages, chemical resistance

Question 19

tricalcium aluminate

Answer 19

hydrates very rapidly

reduces chemical resistance of cement to sulphates

Question 20

tertracalcium aluminoferrite

Answer 20

contributes little to strength. grey colour

Question 21

limestone uses x2

Answer 21

cement
aggregates
(not for coated wearing courses)