Solidification of (Pb–Zn) mine tailings by fly ash-based geopolymer I: influence of alkali reagents ratio and curing condition on compressive strength

In this study, utilization of coal fly ash with higher loss on ignition (LOI) for geopolymer mortar was investigated. The fly ash with approximately 9% of LOI was compared with Class F fly ash. Relationship between heat curing condition and strength was clarified. As the results, although compressive strength of geopolymer mortar with higher LOI was 30-50% smaller, it was available for geopolymer mortar as an alumina silicate material. The higher temperature and the longer period for initial curing, the higher strength was obtained. In order to decrease drying shrinkage, the higher temperature and the longer period for heat curing were required.

Download Full-text

Discussion of “Unconfined Compressive Strength of Synthetic and Natural Mine Tailings Amended with Fly Ash and Cement” by Mohammad H. Gorakhki and Christopher A. Bareither

Journal of Geotechnical and Geoenvironmental Engineering ◽

10.1061/(asce)gt.1943-5606.0001879 ◽

2018 ◽

Vol 144 (5) ◽

pp. 07018009 ◽

Cited By ~ 1

Author(s):

Lucas Festugato ◽

Marina Bellaver Corte

Keyword(s):

Compressive Strength ◽

Fly Ash ◽

Mine Tailings ◽

Unconfined Compressive Strength

Download Full-text

Compressive Strength Development of High-Volume Fly Ash Ultra-High-Performance Concrete under Heat Curing Condition with Time

Applied Sciences ◽

10.3390/app10207107 ◽

2020 ◽

Vol 10 (20) ◽

pp. 7107

Author(s):

Pham Sy Dong ◽

Nguyen Van Tuan ◽

Le Trung Thanh ◽

Nguyen Cong Thang ◽

Viet Hung Cu ◽

...

Keyword(s):

Compressive Strength ◽

Fly Ash ◽

High Performance ◽

High Performance Concrete ◽

High Volume ◽

Strength Development ◽

Ultra High Performance Concrete ◽

Heat Curing ◽

Compressive Strength Development ◽

Curing Condition

This research investigated the effect of fly ash content on the compressive strength development of ultra-high-performance concrete (UHPC) at different curing conditions, i.e., the standard curing condition and the heat curing. A total of 20 mixtures were prepared to cast specimens to measure the compressive strength at different ages from 3 days to 180 days. Additionally, 300 specimens were prepared to estimate the appropriate heat curing period at the early ages in terms of enhancing the 28-day compressive strength of UHPC with high content of fly ash (FA). From the regression analysis using test data, empirical equations were formulated to assess the compressive strength development of UHPC considering the FA content and maturity function. Test results revealed that the preference of the addition of FA for enhancing the compressive strength of UHPC requires the early heat curing procedure which can be recommended as at least 2 days under 90 °C. Moreover, the compressive strength of UHPC with FA under heat curing mostly reached its 28-day strength within 3 days. The proposed models based on the fib 2010 model can be a useful tool to reliably assess the compressive strength development of UHPC with high-volume fly ash (HVFA) (up to 70% fly ash content) under a heat curing condition that possesses a different performance from that of normal- and high-strength concrete. When 50% of the cement content was replaced by FA, the embodied CO2 emission for UHPC mixture reduced up to approximately 50%, which is comparable to the CO2 emission calculated from the conventional normal-strength concrete.

Download Full-text

Lead-Zinc Mine Tailings Valorization Through Fly Ash-Based Geopolymer for Building Material: Synthesis, Microstructure, and Mechanical Properties

10.21203/rs.3.rs-996321/v1 ◽

2021 ◽

Author(s):

ALSENY BAH ◽

Andrea ORTIZ Ramos ◽

Feng Daolun ◽

jie Jin ◽

Alhassane Bah ◽

...

Keyword(s):

Compressive Strength ◽

Fly Ash ◽

Mine Tailings ◽

Unconfined Compressive Strength ◽

Building Materials ◽

Fourier Transforms ◽

Coal Fly Ash ◽

Environmentally Friendly ◽

Cement Industry ◽

Moderate Amount

Abstract Using geopolymerization to value mining wastes in order to meet construction demand is a sustainable and environmentally friendly strategy. Fly ash geopolymer materials have been developed to address environmental issues such as climate change caused by the emissions of CO2 from coal fly ash plants, mining, and cement industry into the atmosphere. The main objective of this study is to study the feasibility of using mine tailings to produce environmentally friendly building materials (so-called geopolymer products) with excellent mechanical strength through fly-based geopolymer technology. Fly ash (F.A.) and mine tailings (M.T.) were utilized as raw materials and gypsum (G.Y.) as additives. Sodium hydroxide (NaOH) at (5-10M) and sodium silicate (water glass) constituted the alkaline solution and were added separately to the mixture. The mechanical property and microstructure of the geopolymers were assessed by performing the Unconfined Compressive Strength (UCS), Scanning Electron Microscopy (SEM), X-ray diffractions (XRD), and Fourier transforms infrared (FTIR). A 24 MPa was achieved at 10M NaOH with 100% F.A. Besides, low UCS values were obtained with only M.T. as a binder. The SEM imaging analysis confirmed similar results showing that the geopolymer specimens cured with 100% of F.A. at 10M NaOH with a moderate amount of gypsum are denser than those prepared without gypsum at 5M. The findings revealed that F.A., MT, and gypsum, together with the alkali reagents, influenced the geopolymerisation process. These factors responded effectively to the microstructural performance(increasing density), resulting in increased unconfined compressive strength.

Download Full-text

Effect of Fly Ash on Compressive Strength of Metakaolin Based Geopolymer

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.873.170 ◽

2017 ◽

Vol 873 ◽

pp. 170-175

Author(s):

Chokkha Siriwan

Keyword(s):

Compressive Strength ◽

Fourier Transform ◽

Fly Ash ◽

Green Technology ◽

Partial Replacement ◽

Steel Mold ◽

Low Emission ◽

Maximum Compressive Strength ◽

Curing Condition ◽

Scanning Electron

Geopolymers were produced through two precursors including solid components and alkaline activators.It was attracted interesting as a green technology because it was the possibility to the remarkably low emission of CO2 in its manufacturing process as compared with Portland Cement (PC). In the present work, the studied program was divided into three steps. In Step 1, Ranong clay (Thailand source) was used as a solid powder and the concentrationof sodium hydroxidewas tested as an alkali solution. After mixing, the geopolymer slurry was casted into a steel mold. The curing condition of all specimens was maintained at 60oC for 24 hrs. The compressive strength of all specimens was tested after curing 1 day. The maximum compressive strength of 10M NaOH was selected intothe next step. In step 2, the partial replacement of 10M NaOH by Na2SiO3 was studied. In this case, 20 wt% of Na2SiO3 was presented as alkaline activatorinto the next step. In step 3, the amount of Fly ash(0%, 10%, 20%, 30%, 40% and 50% by weight) was studied on partial metakaolin replacement. However, the highest compressive strength of 30 wt% fly ashis29.74MPa. To support the results from compressive strength, the microstructure, and geopolymerizationof all compositions were investigated using a scanning electron microscope and a Fourier-transform infrared spectroscopy, respectively.

Download Full-text

Stabilisation of high-sulphide tailings with alkali activated fly ash – mechanical performance

MATEC Web of Conferences ◽

10.1051/matecconf/201927402001 ◽

2019 ◽

Vol 274 ◽

pp. 02001

Author(s):

Cristelo Nuno ◽

Coelho João ◽

Miranda Tiago ◽

Sousa Luis ◽

Fernández-Jiménez Ana ◽

...

Keyword(s):

Compressive Strength ◽

Fly Ash ◽

Mine Tailings ◽

Industrial Waste ◽

Mechanical Performance ◽

Specific Weight ◽

Sulphide Tailings ◽

Alkali Activated ◽

Construction Works

Mine tailings could represent a step forward in terms of the quality of the aggregates that usually accepted in civil engineering applications, due to their specific weight and compressive strength. The Neves-Corvo copper mine produces approximately 3 million tons of tailings every year, which could supply several construction works, at least in the south of Portugal. Nevertheless, this industrial waste requires stabilisation, not only due to their high sulphur content, but also due to mechanical performance demands. This paper focus on the stabilisation, without previous thermal treatment, of the mine tailings from Neves-Corvo.

Download Full-text