The use of waste and by-product materials to reduce cement content in paving blocks

Abstract

Paving blocks factories typically use at least 210 kg cement per m³ to produce paving blocks. The production of Portland cement has significant adverse effects on the environment due to the emission of carbon dioxide. Therefore, reduction of Portland cement content will benefit the carbon footprint of concrete products.
The aim of this research was to reduce Portland cement in paving blocks production without having any adverse effects on the physical and durability characteristics. This research presented the use of non-hazard waste and by products materials such as ground granulated blast furnance slag (GGBS), basic oxygen slag (BOS), run-of-station ash (ROSA), plasterboard gypsum (PG), cement by-pass dust (BPD), incinerator bottom ash aggregate (IBAA), recycled crushed glass (RCG), recycled concrete aggregate (RCA), recycled bricks (RB), together with steel fibre (SF) and PVA-Fibre for the production of environmentally friendly paving blocks. 
Paving blocks were produced by combinations of binary and ternary blends in ten different groups of mixes. The paving blocks were compacted using a hydraulic press to give similar compaction result to factory process. Paving blocks were tested for split tensile strength and compressive strength at 14 and 28 days, slip/skid resistance, weathering resistance, densities were also tested and measured. Furthermore XRD and XRF tests of selected mixes have been carried out. Data obtained from the ternary combinations were analyzed using response surface method and prediction models were created using MINITAB software.
Result of the ten binder mixes showed that BOS up to 70%, ROSA up to 60%, GGBS up to 45%, BPD up to 20%, and PG up to 5% by weight can replace the Portland cement without negative impacts on their desirable properties in accordance to the BS EN 1338: 2003. Moreover, concrete paving blocks prepared with OPC50-GGBS45-BPD5 (OPC7-GGBS6.3-BPD0.7) achieved reduction of cement content by up to 30% in comparison to the percentage currently being used in most factories, without having a substantial impact on the strength or durability of the paving blocks produced in accordance with BS EN 1338:2003. This reduction of cement content corresponds to using only 150 kg cement per m³ for production of paving blocks.

Date of Award	2014
Original language	English
Awarding Institution	Coventry University
Supervisor	Essie Ganjian (Supervisor) & Homayoon Sadeghi Pouya (Supervisor)