CEMENT AND CONCRETE MATERIALS materials fundamentals + mix design Christopher Hall 2009 S131

CEMENT Materials fundamentals Sources of information Cement manufacture + composition Cement hydration Microstructure Concrete mixes Properties: strength permeability durability

Information/texts Jackson & Dhir: Civil Engineering Materials, 5th edn, 1997 Mindess, Young & Darwin: Concrete, 2002 Neville & Brooks: Concrete Technology, 1987 Neville: Properties of Concrete, 4th edn, 1995 Bensted & Barnes: Structure and Performance of Cements, 2nd edn, 2001

Information/journals Cement and Concrete Research Magazine of Concrete Research American Concrete Institute Journal ACI Journal Materials and Structures [RILEM]

Information/websites Virtual Cement & Concrete Testing Laboratory includes Electronic monograph from Bentz at NIST: See also microstructure images library from Lange at UIUC:

Cement Manufacture Raw materials limestone + clay on firing, produces a complex mixture of synthetic minerals, principally calcium silicates and calcium aluminates

Manufacture

CEMENT World production billion tons

CEMENT World production billion tons Steel production 900 million tons

CEMENT World production billion tonnes 2--5 % total CO 2 emission Energy intensive manufacture Various figures are quoted. The energy cost of manufacture is around 3500 kJ/kg cement

CEMENT World production billion tonnes EU production million tonnes For each tonne cement produced tonne CO 2 is also produced tonne from decalcination of limestone tonne from combustion of fuel in the kiln tonne from electricity production

CEMENT In EU, cement industry produces 3 per cent of total anthropogenic CO 2 Source: Cembureau

CEMENT COMPOSITIONS CaO SiO 2 Al 2 O 3  Fe 2 O 3 OPC zone

CEMENT COMPOSITION Notation CaO Al 2 O 3 Fe 2 O 3 SiO 2

CEMENT COMPOSITION Notation CaO C Al 2 O 3 A Fe 2 O 3 F SiO 2 S

CEMENT COMPOSITION Notation CaO C Al 2 O 3 A Fe 2 O 3 F SiO 2 S

Clinker microstructure C 3 S C 2 S C 3 A C 4 AF 150 micron C3SC3S C2SC2S

Clinker microstructure C 3 S C 2 S C 3 A C 4 AF 150 micron C3SC3S C2SC2S

Clinker microstructure C 3 S C 2 S C 3 A C 4 AF 150 micron C3SC3S C2SC2S

Clinker microstructure C 3 S C 2 S C 2 A C 4 AF C 3 A C 4 AF

C 3 A C 4 AF

Clinker microstructure C 3 S, C 2 S, C 3 A, C 4 AF 200 micron

Cement grinding Gypsum additions (strictly sulphate) Particle size distribution Images from Lange UIUC

Cement hydration 1 Heat evolution Induction period

Cement hydration 2 Chemical reaction with water All minerals involved 115 micron

Cement hydration 2 Principal reaction which develops strength C 3 S + water ---> C-S-H

Cement hydration 3 Chemical reaction with water All minerals involved Formation of lime (calcium hydroxide) pH of pore water

Cement hydration 4 Water requirement about 30% by wt cement for complete reaction

Cement hydration 5 Four stages of hydration in a microstructural model of C 3 S hydration. The degrees of hydration are: top left--0% top right--20%, bottom left--50% bottom right--87% Red=unreacted cement blue=CH yellow=C-S-H black= porosity from Bentz, NIST

Computational materials science Cellular automaton model of cement and concrete D Bentz and E Garboczi NIST

Cement hydration 6 Synchrotron X-ray view

Summary of setting and hardening Workability Development of continuous network of hydrate material Strength development Porosity and permeability Timescale

Strength and strength development

Cement Based Materials Mortars Concrete Manufactured cement based materials Autoclaved aerated concrete

Transport properties Permeability Sorptivity see Hall & Hoff: Water Transport in Brick, Stone and Concrete 2002

PERMEABILITY property Darcy’s law: u = Q/A = -  k  p /L k permeability Q volume rate of flow

A B

Types of cements Portland cement Blended or composite cements Portland + other mineral components

BS EN Cement Other mineral components are Minerals which react with lime Pozzolans Blastfurnace slag Fly ash Natural pozzolans Inert fillers Crushed limestone

BS EN Cement