CEMENTITIOUS STABILISATION OF ROAD CONSTRUCTION MATERIALS: QUO VADIS Phil Paige-Green, CSIR-Transportek, Pretoria Frank Netterberg Consultant

INTRODUCTION l Stabilisation of marginal materials is still an important part of road building in RSA l Will probably become more important as good materials are depleted l Specification of stabilisation is based on: –COLTO Standard Specs for R&B (1996) –with assistance from Draft TRH 13 (1986)

INTRODUCTION l Cement stabilisation experience incorporated in COLTO and TRH13 was based mainly on the use of: –Ordinary Portland Cement (SABS 471) –PBFC (SABS 626) –Portland cement blends (SABS 831) –Portland flyash cement (SABS 1466) l Things have changed !!

SABS ENV l In 1992, became a European pre-standard (ENV) l After 3 years should be upgraded to European standard (EN) ?? l Adopted “as is” by SABS in 1996 for RSA l Applicable to “common cements” l Similar spec for masonry cements (SABS ENV 413-1) l Concentrate on SABS ENV as this is most relevant for roads

NEW REQUIREMENTS l Totally different classification system l 5 cement types –9 groups (depend on additive) l 19 subgroups (depend on composition) l Also classified by strength and rate of strength gain (6 additional permutations)

CLASSIFICATION l IPortland cement l IIOther Portland cements l Portland slag cement l Portland silica fume cement l Portland flyash cement l Portland limestone cement l Portland composite cement l IIIBlastfurnace cement l IVPozzolanic cement l VComposite cement

Strength requirements Strength class Compressive strength (MPa) Early strengthStandard strength 2 days7 days28 days 32.5-≥ 16.0≥ 32.5≤ R≥ ≥ 10.0-≥ 42.5≤ ,5R≥ ≥ 20.0-≥ R≥ 30.0-

STANDARD DESIGNATION l Cement ENV CEM I 32.5 –(equiv to OPC ?) l Cement ENV CEM II/A-S 42.5

CHEMICAL PROPERTIES SABS 471SABS ENV Lime sat factor CaO/SiO 2 ≥ 2 MgO cement ≤ 5%MgO clinker ≤ 5% Max SO 3 = 3.0 – 3.5 %Max SO 3 = 3.5 – 4.0 % (4.5) Max LoI = 4 %Max LoI = 5 % Max insoluble residue = 2.5%Max insoluble residue = 5% Chloride N/SMax chloride 0.1% Pozzolanicity N/SPozzolanicity - Yes

PHYSICAL PROPERTIES PropertySABS 471ENV Max % >212 μm (RH) N/S Min specific surface area (cm 2 /g) (RH) N/S Min UCS (MPa) 3 days 7 days (RH) (RH) Earlier table Min transverse str (MPa) 3 days 7 days (RH) (RH) N/S

PHYSICAL PROPERTIES (cont) PropertySABS 471ENV Setting times: Min initial (min) Max final (hrs) (RH) (RH) 45 – 60 N/S Soundness: Max expansion (mm) (RH)10

STRENGTH

Strength requirements Strength class Compressive strength (MPa) Early strengthStandard strength 2 days7 days28 days 32.5-≥ 16.0≥ 32.5≤ R≥ ≥ 10.0-≥ 42.5≤ ,5R≥ ≥ 20.0-≥ R≥ 30.0-

CHEMICAL PROPERTIES SABS 471SABS ENV Lime sat factor CaO/SiO 2 ≥ 2 MgO cement ≤ 5%MgO clinker ≤ 5% Max SO 3 = 3.0 – 3.5 %Max SO 3 = 3.5 – 4.0 % (4.5) Max LoI = 4 %Max LoI = 5 % Max insoluble residue = 2.5%Max insoluble residue = 5% Chloride N/SMax chloride 0.1% Pozzolanicity N/SPozzolanicity - Yes

PHYSICAL PROPERTIES PropertySABS 471ENV Max % >212 μm (RH) N/S Min specific surface area (cm 2 /g) (RH) N/S Min UCS (MPa) 3 days 7 days (RH) (RH) Earlier table Min transverse str (MPa) 3 days 7 days (RH) (RH) N/S

PHYSICAL PROPERTIES (cont) PropertySABS 471ENV Setting times: Min initial (min) Max final (hrs) (RH) (RH) 45 – 60 N/S Soundness: Max expansion (mm) (RH)10

STRENGTH