Slurrybound Macadam Slurrybound Macadam

as as

Surfacing OptionSurfacing Option

Johan HattinghJohan HattinghJohan HattinghJohan Hattingh

May 2005May 2005

1.1. IntroductionIntroduction

2.2. Overview on the recent development of the Macadam Overview on the recent development of the Macadam

TechnologyTechnology

3.3. Research WorkResearch Work

3.1 Laboratory test

3.2 Improved construction techniques

4.4. ConclusionConclusion

IndexIndex

1. Introduction1. Introduction

Report back on research work

To date limited to layerworks

Existing laboratory tests not suitable for the slurrybound

macadam surfacing option

Design and specifications more a ‘mog dit troffe’ approach

Riding quality / Equipment

2.2. Brief overview on recent development Brief overview on recent development

of the Macadam Technologyof the Macadam Technology

Theme: From base technology using ballast / coarse aggregate to surface technologies

Slurry armoring on WB-base.Seaslope Interchange. (Roux / Otto – CSIR)(Early 90’s)

Filler sand substituted by bituminious slurry.

Thick slurrybound Macadam layers using railway ballast.

Baragwanath Hospital (Potgieter, Hattingh).

Bus bays in Mohlakeng (1993).

Slurrybound Macadam with reduced bitumen content in

penetration slurry 37mm stone mix (Doornkop Soweto).

(1994).

Composite Macadam (37mm stone bottom / 26mm top with rich slurry)

>200km street network constructed.

Masabeni Street, Springs / Attridgeville / Mamelodi / Kagiso /

New Brighton etc.

SABITA-award, 1995.

50mm Slurrybound Macadam (26mm stone size)

Mamelodi / Attridgeville / Kagiso

> 200km. (1995 – 1997).

15mm – 25mm thick Slurrybound Macadam

> 200km.

Leroro / Kagiso / Mamelodi

Overlay applications with varying thicknesses.

Marakele National Park / Makapan Tower Road / Kagiso

Introduction of the spinning beam on guiderails

Soweto

(2004)

3.3. Research workResearch work

3.1 LABORATORY

Current tests all base (layerwork) related:

Materials: Grading, ALV, PI, etc.

Density: Rondavel tests

Strength parameters: CPA-method / Stability / BinderContent on slurry only

Challenges:- Densification of the Marshall briquette

- Penetration of the slurry without disturbing the stone skeleton

- The use of a bitumen emulsion in the preparation of the briquette

(CPA-method: Emulsion substituted by pen-grade binder)

Proposed revised briquette preparation:

- Mount a Proctor-mould to a vibratory table.

- Fill the mould with the coarse aggregate to half 32mm.

- Place the Marshall hammer as loose weight on the coarse aggregate and vibrate (using the table) for 60 seconds.

- Wet the aggregate using either water or a bitumen-emulsion 1

- Mix the slurry to specified consistency using the flow-plate 2

- Place the determined 3 volume slurry on top of the coarse aggregate with the Marshall hammer as loose weight on top and allow the table to vibrate for 60 seconds.

- Repeat the above to achieve 60mm briquette thickness.

- Cure the briquette in the mould before stripping.

- Densify briquettes (30 blows) with Marshall hammer after preheating.

- Briquettes ready for further Marshall tests.

1 Deduct volume used from optimum emulsion content.

2 Optimum slurry mix and consistency is a separate exercise.

3 Determined in terms of volumetric principles through experimentation

Wet aggregate 1 layer 1% Cement 8% net Binder slurry flowable*

Wet aggregate 1 layer 1% Cement 8% net Binder slurry flowable*

Wet aggregate 1 layer 1% Cement 8% net Binder slurry flowable*

* Compaction: Vibrated without surgarge weight then level and vibrated with surgarge weight

Test results on SB-briquettes

3.2 IMPROVED CONSTRUCTION TECHNIQUES

3.2 IMPROVED CONSTRUCTION TECHNIQUES (continued)

3.2 IMPROVED CONSTRUCTION TECHNIQUES (continued)

4. Conclusion4. Conclusion

Research, design and specifications now scientific using

Marshall principles

High quality construction with improve riding quality

Workforce at least three times higher than conventional

5 point scale5 point scale

ANALYSIS OF ROAD ACTIVITES AGAINST COSTS, TIME, ANALYSIS OF ROAD ACTIVITES AGAINST COSTS, TIME, QUALITY SUITABILITY, LABOUR COMPONENT AND APPLICATIONQUALITY SUITABILITY, LABOUR COMPONENT AND APPLICATION