Mechanical Properties and Durability of High-Performance Concretes Blended with Circulating Fluidized Bed Combustion Ash and Slag as Replacement for Ordinary Portland Cement

Zhi Cheng,Vojtěch Václavík,Zhe Ma,Lei He,Xiaobo Pei,Lan Liu,Zhijun Cheng

doi:10.1155/2020/8613106

Abstract

This study investigates the mechanical properties and durability of three families of high-performance concrete (HPC), in which the first was blended with fly ash, the second with circulating fluidized bed combustion (CFBC) ash, and the third with CFBC slag. In addition to each of the three mineral additives, silica fume and a superplasticizer were also incorporated into the HPC. Hence, three families of HPC, containing 10%, 20%, and 30% mineral admixtures and 9% silica fume of the binder mass, respectively, were produced. The microstructure and hydration products of the HPC families were examined by scanning electron microscopy (SEM) and X-ray diffraction (XRD) to explore the influence of fly ash, CFBC ash, and CFBC slag on the compressive strength and frost resistance of HPC. The experimental results show that the compressive strength of HPC could reach 60 MPa at 28 d age. When the fly ash content was 30%, the compressive strength of HPC was 70.2 MPa at 28 d age; after the freeze-thaw cycle, the mass loss and strength loss of HPC were 0.63% and 8.9%, respectively. When the CFBC ash content was 20%, the compressive strength of HPC was 75 MPa at 28 d age. After the freeze-thaw cycle, the mass loss and strength loss of HPC were 0.17% and 0.81%, respectively.

Highlights

Coal-fired power generation in traditional thermal power plants results in the emission of a large amount of sulfur dioxide (SO2), causing serious environmental pollution [1]
Ash and slag pollute the environment while occupying the land; governments and power plants have sought effective methods to dispose them [15,16,17,18], especially since the environmental protection tax law was enacted on January 1, 2018
Nguyen et al [31] studied the engineering performance and durability of concrete modified with circulating fluidized bed combustion (CFBC) ash so that it contained a high volume of low-calcium fly ash. e experiment results showed that the CFBC ash addition did not influence the stability and passing and filling abilities of concrete

Summary

Introduction

Coal-fired power generation in traditional thermal power plants results in the emission of a large amount of sulfur dioxide (SO2), causing serious environmental pollution [1]. Erefore, this technology has been vigorously promoted in China [2,3,4] In this technique, limestone is added as a desulfurizer to the CFBC boiler, so that the boiler discharges a greater amount of ash and slag compared with the pulverized coal boiler [5,6,7]. Nguyen et al [31] studied the engineering performance and durability of concrete modified with CFBC ash so that it contained a high volume of low-calcium fly ash. Excessive f-CaO and II-CaSO4 will cause concrete damage due to volume expansion in the later stage [32,33,34] To eliminate this adverse effect, CFBC ash and CFBC slag should be modified by physical or chemical methods. To prepare HPC, fly ash, CFBC ash, and ground CFBC slag were used as admixtures to replace cement. e influences of different admixtures on the mechanical properties and durability of HPC were explored. e research results can provide a new basis and reference for the utilization of CFBC ash and slag and the preparation of HPC

Materials and Methods

Results and Discussion

Conclusions