Effect of Burn Joss Paper Ash on Properties of Ground-Granulated Blast Furnace-Based Slag Geopolymer

Wen-Ten Kuo,Zhi-Rong Chen,Chuen-Ul Juang

doi:10.3390/app10144877

Abstract

The purpose of this study is to make geopolymers using burned joss paper ash (BJPA)—which is used in traditional Chinese festivals—and ground-granulated blast-furnace slag (GGBFS). GGBFS-based geopolymers were replaced by BJPA, by mass, at levels of 0%, 20%, 40%, 60%, 80% and 100% and the liquid-to-solid ratios (L/Ss) were 0.3, 0.4 and 0.5. The properties of fresh, hardening, durability and microscopic analysis were examined to determine the effect of BJPA-substitution ratios and L/S on the engineering properties of composite geopolymers. The results show that among the fresh properties, as the amount of BJPA replacement increases, the setting time tended to increase, but the fluidity slowed down. The maximum compressive strength reached 81.1 MPa. As the amount of BJPA replacement increased, the elastic modulus of the geopolymer increased and the brittleness decreased. However, in the dry shrinkage test, it was found that an increase in BJPA helped reduce the dry shrinkage of the geopolymer. X-ray diffraction analysis revealed that a rise in the BJPA-substitution ratio increased the peak value of calcium carbonate. Scanning electron microscope images showed that microcrack size decreased with an increase in the BJPA-substitution ratio, with maximum and minimum crack sizes of 5.80 μm and 176.8 nm, respectively. This was because BJPA was unable to undergo complete polymerization and therefore was able to fill the cracks produced during the polymerization. In conclusion, BJPA may be used for waste recycling in the production of geopolymers.

Highlights

Ordinary Portland cement (OPC) is made of blends of mineral admixtures and its usage as a binder of concrete material [1]
The setting time of the burned joss paper ash (BJPA)–ground-granulated blast-furnace slag (GGBFS) composite geopolymer increased with a rise in the liquid-to-solid ratios (L/Ss) and BJPA-substitution ratios
An L/S of 0.5 and BJPA-substitution ratio of 100% resulted in the longest initial (126 min) and final (183 min) setting times; The slump flow value dramatically decreased at BJPA-substitution ratios of 60%, 80% and 100%, whereas the slump value dropped with a rise in the L/S

Summary

Introduction

Ordinary Portland cement (OPC) is made of blends of mineral admixtures and its usage as a binder of concrete material [1]. Cement can provide the main strength source of OPC, its manufacturing process greatly affects the environmental pollution. The carbon dioxide emissions produced each year account for 6% of the global total [2]. Geopolymer is an engineering material term coined by Joseph Davidovits in 1978. It describes this kind of material as a geotechnical material with similar adhesive properties and can have the conditions to replace cement [3,4,5,6]. The main reaction of geopolymerization is to produce two chemical reactions with sodium hydroxide (NaOH) through silicon (Si) or aluminum (Al). The first reaction will destroy the structure of its chemical chain and cause Si or Al to be released from the material; The two reactions will become anhydrous calcium silicate and initiate

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Discussion

Conclusion