THE UTILIZATION OF RECLAIMED WASTE-TO-ENERGY AGGREGATES AS LIGHTWEIGHT SAND IN CONCRETE MASONRY UNITS AND PRECAST CONCRETE

ABSTRACT

In the United States, solid waste is being generated and disposed of in landfills at an alarming rate of 50-60% due to a lack of technology and regulations in place to reuse the waste. Municipal solid waste incinerator (MSWI) plants process this waste by burning the waste to ash thus, reducing the volume by 80-90%. Typically, this ash is disposed of in landfills which is unsustainable practice. Additionally, with China’s new anti-pollution stringent regulations set in place, the recycling market in the United States is continuing to grow unstable. A process has been developed to refine solid waste ash into a lightweight sand-like material known as reclaimed sands. Reclaimed sands are a Department of Environmental Protection (DEP) approved material, and a 100% postconsumer product allowing it to potentially qualify for Leadership in Energy and Environmental Design (LEED) accreditation. This work investigates the utilization of reclaimed sands in two different applications. First, this paper discusses the use of reclaimed sands as a lightweight fine aggregate replacement in concrete masonry units (CMU). The production, structural performance and analysis of the blocks were assessed per the corresponding ASTM standards where it was found that some of the block mixes meet physical properties and strength requirements. In addition, reclaimed sands were analyzed in internally cured precast and cast-in-place mixes. Mix designs were tested for compressive strength and permeability of the concrete samples. It was concluded that the addition of reclaimed sands in combination with proper proportioning of admixtures, can reduce the permeability of precast concrete mixes and that precast concrete mixes containing prewetted reclaimed sands can maintain a high compressive strength over time.

 

 

 

TABLE OF CONTENTS

LIST OF FIGURES ………………………………………………………………………………………………….. vi

LIST OF TABLES ……………………………………………………………………………………………………. viii

ACKNOWLEDGEMENTS ……………………………………………………………………………………….. ix

Chapter 1  Introduction ……………………………………………………………………………………………… 1

Chapter 2  Background ……………………………………………………………………………………………… 3

2.1 – Solid Waste Incinerator Plants ……………………………………………………………… 3

2.2 – Incinerator Ash Recycling ……………………………………………………………………. 4

2.3 – Masonry Blocks with Incinerator Ash……………………………………………………. 6

2.4 – Lightweight Aggregates in the Northeast United States …………………………… 7

2.5 – Environmental Requirements ……………………………………………………………….. 9

2.6 – Lightweight Aggregates and Internal Curing Concrete …………………………….. 11

Chapter 3  Materials and Test Methods ……………………………………………………………………….. 13

3.1 – Mix Designs ………………………………………………………………………………………. 14

3.1.1 – Brick Testing Mix Designs………………………………………………………………… 14

3.1.2 – Production Run 1 Mix Designs ………………………………………………………….. 16

3.1.3 – Production Run 2 Mix Designs ………………………………………………………….. 16

3.1.4 – Precast Concrete Mix Designs …………………………………………………………… 17

3.2 – Manufacturing and Testing Methodology ………………………………………………. 21

3.2.1 – Brick Manufacturing and Testing Methodology …………………………………… 21

3.2.2 – Production Run 1 and 2 Manufacturing and Testing Methodology …………. 25

3.2.3 – Leaching Analysis of Block ………………………………………………………………. 29

3.2.4 – CMU Physical Property Testing and Dimensions …………………………………. 30

3.2.5 – Rapid Chloride Permeability Testing Methodology………………………………. 34

Chapter 4  Testing Results and Discussion …………………………………………………………………… 38

4.1 – Brick Testing results ……………………………………………………………………………. 38

4.1.2 – Production Run 1 ASTM Test Results ………………………………………………… 44

4.1.3 – Production Run 2 testing Results ……………………………………………………….. 484.1.4 – Production Run 2 Re-Test Results ……………………………………………………… 504.1.5 – Leaching Testing Results ………………………………………………………………….. 51

4.1.6 – Rapid Chloride Permeability and Compression Strength Test Results …….. 52

Chapter 5  Conclusions ……………………………………………………………………………………………… 57

References ……………………………………………………………………………………………………………….. 61

Chapter 1

 

Introduction

The United States Environmental Protection Agency (EPA) reports that in 2017, the total amount of Municipal Solid Waste generated was 267.8 million tons or approximately, 4.51 pounds per person per day [1] . Of this amount generated, approximately 67 million tons were recycled and 27 million tons were composted. About 35%, or 94 million tons of MSW were recycled and composted. More than 34 million tons of waste were combusted with energy recovery and finally, more than 50%, equivalent to 139 million tons of waste was disposed of in a landfill [1] .

As evident through data collection, the amount of solid waste generated increases every year, increasing concern about landfill space restriction, groundwater contamination and methane gas emission as a result. With the implementation of China’s new anti-pollution policy, the recycling market in the United States is becoming an even greater concern. Municipal solid waste incinerators (MSWI) or Waste-to-Energy (WtE) facilities provide a sustainable solution to significantly reduce disposal volume, by incinerating waste versus sending it to a landfill. European and Asian countries have developed and established managements and disposal methods for the ash. However, the United States lacks regulations and an active strategy to address this issue.

The goal of this project was to test the viability of using municipal solid waste incinerator ash in Concrete Masonry Units. This material was obtained from a local Solid Waste Incinerator plant and then post-processed. In order to pursue this research, it was necessary to conduct leaching testing on the material prior to utilizing it in the mix designs. Once verified, physical properties of this material were obtained in order to develop initial mix designs to begin the research. After establishing initial designs, preliminary testing was performed on small-scale bricks in order to narrow down successful mix designs that would be utilized for full-scale block production. Once the full-scale blocks were manufactured, physical properties, compression testing, and leaching testing were performed and compared to the associated ASTM standards and

Department of Environmental Protection (DEP) permit limits.

While the use of MSWI ash is fully explored for its use in masonry blocks, its use in internally cured precast concrete mixes was also examined. The production of lightweight aggregates is very minimal in the North Eastern United States, thus most lightweight aggregates are produced and shipped from the South. Due to this materials’ lightweight properties, its use in internally cured concrete would allow for the production of more durable concrete.

This research studied the performance of the MSWI ash as lightweight aggregate replacement in internally cured concrete utilized in both precast and cast-in-place mixes. Specifically, the specimens were tested for compressive strength and permeability. The precast concrete mix utilized for this research is typically used for agricultural and roadway purposes in order to neutralize animal waste. The Rapid Chloride Permeability (RCP) test helps provide an indirect assessment of how permeable concrete mixes will behave when exposed to salts and other harsh chemicals. The initial mix design was obtained from a local precast manufacturer and replaced with a percentage of pre-treated lightweight aggregate material in addition to a modified amounts of admixtures with respect to the properties of reclaimed sands. Testing methodology per ASTM standards and results will be discussed and compared to the precast control sample obtained from the precast manufacturer. The preceding chapters will further discuss the different mix designs tested, manufacturing and testing procedures, as well as results obtained.

THE UTILIZATION OF RECLAIMED WASTE-TO-ENERGY AGGREGATES AS LIGHTWEIGHT SAND IN CONCRETE MASONRY UNITS AND PRECAST CONCRETE

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