COMPRESSIVE STRENGTH OF A CONCRETE MIX FOR PAVEMENT BLOCKS INCORPORATING INDUSTRIAL BY-PRODUCT

1. COMPRESSIVE STRENGTH OF A CONCRETE MIX FOR PAVEMENT BLOCKS INCORPORATING INDUSTRIAL BY-PRODUCT R Mokoena and M. B Mgangira Southern Africa Transport Conference 2017 CSIR International Conference Centre 10 July 2017

2. Context Thank you

3. Introduction Context Introduction

4. Context Optimisation in the use of industrial by-products Improvement in workability using a biological activator Introduction

5. Context To evaluate the use of microbes, microbial derived metabolites and other biodegradable and eco-friendly additives for stabilisation and compaction. Introduction

6. Initiatives at CSIR Horak and Maree (1982) Slag as base in trial sections Thank you

7. Context • To provide coherent body of knowledge on alternative materials • Review available test procedures for assessment • Establish best material preparation • Explore possible modifications to improve suitability • Establish the required adaptation for use • Overall: Guideline documents for specific materials Thank you

8. Material characterization Microstructure Longitudinal Cracking

9. Material characterisation Microstructure Energy Dispersive Spectroscopy (EDS) Longitudinal Cracking

10. Material characterization • The target strength for the concrete 30 Mpa • Compressive strength tests were conducted according to SANS 5863. The cast concrete cubes were tested at 7, 14, 28 and 56 days. Each test batch was prepared for a specific age. • Improvement in workability • Use of a biological activator to improve the workability of the concrete. Products of fermentation processes. They consist of fermented organic matter, water, and other proprietary ingredients.

11. Material characterization Concrete mixes with the activator are labelled as 5A, 5B, 8A and 8B.

12. Strength development for mixes 1, 2 and 3 with w:b = 0.46 Severe Rutting

13. Strength development for mixes 4, 5 and 6 with w:b = 0.36 Extent of investigation depends on the client requirements

14. Strength development for mixes 8 and 9 with w:b = 0.28 Extent of investigation depends on the client requirements

15. Achievable strength 56-day compressive strength, MPa 28-day compressive strength, MPa

16. Slump of mixes with Biological activitor Combination of failures

17. Strength of mixes with Biological activator Unawareness Inexperience Mistakes such as noncompliance Slips and lack of attention Addition of biological activator slightly improved workability, a reduction in compressive strength was also observed with an increase in activator

18. Conclusion Identified optimised mixture for required strength for block paving Addition of biological activator slightly improved workability, a reduction in compressive strength was also observed with an increase in activator Unawareness Inexperience Mistakes such as noncompliance Slips and lack of attention

19. Way Forward Assessment of the durability of the selected mix with particular reference to concrete block paving and incorporating other “by-products materials” into the concrete mix in order to produce a functional concrete paving block system in support of the principle of sustainably-oriented road infrastructure development. Improved Biological activator Unawareness Inexperience Mistakes such as noncompliance Slips and lack of attention

20. Thank you