The Influence of Nano-SiO2 and Recycled Polypropylene Plastic Content on Physical, Mechanical, and Shrinkage Properties of Mortar

Haiming Chen,Donglei Zhang,Yangchen Xu,Yuntao Zhu,Le Huang,Lingxia Huang

doi:10.1155/2019/6960216

Haiming Chen, Donglei Zhang + Show 4 more

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https://doi.org/10.1155/2019/6960216

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Abstract

This work is aimed to study the possibility of recycling plastic waste (polypropylene (PP)) as aggregate instead of sand in the manufacturing of mortar or concrete. For this, an experimental study was carried out to evaluate the influence of nano-SiO2 and recycled PP plastic particles' content on physical, mechanical, and shrinkage properties and microstructure of the mortars with recycled PP plastic particles. The sand is substituted with the recycled PP plastic particles at dosages (0%, 20%, 40%, and 60% by volume of the sand). The nano-SiO2 content is 5% by weight of cement. The physical (porosity, water absorption, and density), mechanical (compressive and flexural strength) and shrinkage properties of the mortars were evaluated, and a complementary study on microstructure of the interface between cementitious matrix and PP plastic particles was made. The measurements of physical and mechanical properties showed that PP-filled mortar had lower density and better toughness (higher ratio of flexural strength to compressive strength). However, the compressive strength and flexural strength of PP-filled mortar is reduced, and the porosity, water absorption, autogenous shrinkage, and dry shrinkage increased as compared to normal cement mortar. The addition of nano-SiO2 reduced the porosity, water absorption, and drying shrinkage of PP-filled mortar and effectively improved the mechanical properties, but increased its autogenous shrinkage. A microscopic study of the interfacial zone (plastic-binder) has shown that there is poor adhesion between PP plastic particles and cement paste. From this work, it is found that recycled PP plastic waste has a great potential to be a construction material. It can be used as partial replacement of natural aggregates instead.

Highlights

Plastic, a common macromolecule compound, is widely used in all walks of life for its excellent properties of low density, high durability, high impact resistance, and easy processing [1]
Based on the above research results, the purpose of this paper is to study the possibility of recycling plastic waste as aggregate partially instead of sand in the mortar or concrete, the effects of recycled PP plastic particles content and nano-SiO2 on physical, mechanical, and shrinkage properties of mortar, and to analyze the microcharacteristics of PP-filled mortar with nano-SiO2 by scanning electron microscopy (SEM). e research results can provide references for the application of plastic waste and nanotechnology in concrete or mortar
Mix Design and Processing of Mortars. e mix proportions of mortars are shown in Table 2. e content of the superplasticizer was the percentage of the weight of the cementitious materials. e dosage of superplasticizer was controlled in order to avoid the floating phenomenon of recycled PP plastic particles due to its light density. e plastic particles were added into mortars replacing 0%, 20%, 40%, and 60% sand by volume. e nano-SiO2 content was the 5% by weight of cement

Summary

Introduction

A common macromolecule compound, is widely used in all walks of life for its excellent properties of low density, high durability, high impact resistance, and easy processing [1]. China is a big producer of plastics, and a big consumer of plastics. The main treatment methods of plastic waste in various countries are landfill, incineration, and transportation to other countries. Due to the very low biodegradability of plastic waste [4,5,6], landfill will make it exist in the soil for a long time, increasing the burden of land resources, while incineration of plastic waste will produce polycyclic aromatic hydrocarbons, carbon monoxide, and other harmful substances, thereby seriously contaminating the environment. Under the background of global resource shortage, recycling plastic waste can reduce resource waste, avoid environmental pollution, and achieve sustainable development. The status of recycling plastic waste is not satisfactory. Even in the developed countries, it is difficult to have a high

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