Bioactivity enhancement of calcined kaolin geopolymer with CaCl2 treatment

This paper reports that surface treatment with CaCl2 enhances the bioactivity of a calcined kaolin geopolymer. Calcined kaolin, NaOH solution, sodium silicate solution, and heat curing were used to form geopolymer pastes. A soaked-treatment method was applied to the geopolymer samples using CaCl2 solution as the ion exchange agent. The bioactivity of the material was determined by the simulated body fluid (SBF) in vitro testing method. Scanning electron microscope images showed a dense apatite formation on the treated geopolymer surface after SBF immersion for only 3 days. The CaCl2 treatment promoted compressive strength and enhanced bioactivity by accelerating apatite precipitation and slowing down the rise in pH.This work was financially supported by the Higher Education Research Promotion and National Research University Project of Thailand, Office of the Higher Education Commission, through the Advanced Functional Materials Cluster of Khon Kaen University; and Khon Kaen University and the Thailand Research Fund (TRF) under the TRF-Royal Golden Jubilee Ph. D. program (Grant no. PHD/0143/2554); Post-doctoral training program (Grant no. 58110), Graduate school, Khon Kaen University and TRF Senior Research Scholar Contract No. RTA5780004.info:eu-repo/semantics/publishedVersio

Apatite formation on calcined kaolin-white Portland cement geopolymer

In this study, calcined kaolin–white Portland cement geopolymerwas investigated for use as biomaterial. Sodiumhydroxide and sodium silicate were used as activators. In vitro test was performed with simulated body fluid (SBF) for bioactivity characterization. The formation of hydroxyapatite bio-layer on the 28-day soaked samples surface was tested using SEM, EDS and XRD analyses. The results showed that the morphology of hydroxyapatite was affected by the source material composition, alkali concentration and curing temperature. The calcined kaolin–white Portland cement geopolymer with relatively high compressive strength could be fabricated for use as biomaterial. The mix with 50% white Portland cement and 50% calcined kaolin had 28-day compressive strength of 59.0 MPa and the hydroxyapatite bio-layer on the 28-day soaked sample surface was clearly evident.This work was financially supported by the Thailand Research Fund (TRF) and Khon Kaen University under the TRF-Royal Golden Jubilee Ph.D. program (Grant No. PHD/0143/2554) and TRF-Senior Research Scholar (Grant No. RTA5780004)

An evaluation of the suitability of SUPERPAVE and Marshall asphalt mix designs as they relate to Thailand’s climatic conditions

The most commonly-used asphalt mix design in Thailand still relies on the Marshall Mix design procedure which is empirical in its nature, in the sense that it is based on data produced by experiment and observation rather than reliable “in-field” data. As a result of this, the Marshall Mix design procedure has substantial drawbacks with respect to replicating the real or actual behaviour of asphalt during construction and in actual in-service conditions. The Strategic Highway Research Program (SHRP) has developed the Superior Performance Asphalt Pavements (SUPERPAVE) mix design procedure, which shifts to a large degree away from the empiricism of the Marshall Mix design to provide a more reliable and responsive solution to actual pavement conditions. This study aims to evaluate whether the SUPERPAVE mix design procedure can be reliably implemented under Thailand pavement conditions. A map of the Performance Grade (PG) asphalt binders was generated to cover the study area, namely the North part of Thailand, according to the SUPERPAVE asphalt classification with the highest and lowest temperature ranges that the asphalt might be subjected to. Using local materials, and considering loading and environmental conditions, a comparative study of the performance of two mixes, designed using SUPERPAVE and Marshall Mix design procedures, was carried out. The SUPERPAVE mixes proved superior to the Marshall Mixes. However, the asphalt binder commonly used in Thailand is not suitable for Thailand pavement conditions, based on the PG grade asphalt classification system

Creep properties of cement and alkali activated fly ash materials using nanoindentation technique

This paper presents creep properties of cement and alkali activated fly ash (AAFA) paste and mortar determined from statistical analysis of nanoindentation data. Cement paste having 95 MPa compressive strength at 28 days was tested for comparison and validation with a conventional test. Using nanoindentation, the specific creep of the cement paste after one year was predicted as 18.32 microstrain/MPa. For AAFA samples, an experimental program was set up using Taguchi's Design of Experiment method to consider four parameters, silica fume, sand to binder ratio, liquid to solid ratio, and superplasticiser, each with three variations.Using ANOVA, the percentage contributions of these parameters on the creep modulus of AAFA samples are: silica fume 26%, sand to binder ratio 21%, liquid to solid ratio 22%, and superplasticiser 31%. The results using de convolution technique to identify the creep modulus of different phases of AAFA matrices show that partly-activated, non-activated slag and non-activated compact glass phases are leading the creep behaviour of AAFA samples due to their high creep modulus. Compare to other parameters, the liquid to solid ratio contributes the most to the creep property of partly-activated slag, non-activated slag and non-activated compact glass phases, that is, 51%, 89%, 68%, respectively. Sand to binder ratio and superplasticiser have minor effect on the creep behaviour. The results of the creep properties of AAFA paste were then compared with those of AAFA concrete using an upscaling process. The creep rate of AAFA concrete was defined by the creep properties of the matrix and the interface between aggregates and matrix assuming perfect bonding and slip bonding conditions. The results from the upscaling process show that the creep properties of AAFA paste from nanoindentation are representative of the long-term creep properties of AAFA concrete determined from a conventional test method

Recycled Concrete Aggregates in Roadways: A Laboratory Examination of Self-Cementing Characteristics

This paper examines the self-cementing phenomenon of the road construction material known as recycled concrete aggregate (RCA). Two RCA types were selected as study materials: (1) high-grade RCA (HRCA), a quality RCA manufactured from relatively high-strength concrete structures; and (2) road base RCA (RBRCA), a high-grade RCA blend combined with brick and general clean rubble (road base material). Laboratory tests were performed to obtain the unconfined compressive strength, indirect tension dynamic modulus, and resilient modulus of the test samples to examine their hardening characteristics when subjected to varying curing periods. These tests were performed in conjunction with microstructure analyses from X-ray diffractometry (XRD) and scanning electron microscope (SEM) techniques. The HRCA samples, which were prepared and subjected to varying curing conditions, transformed from an initially unbound material into a bound (fully stabilized) material. The results of XRD and SEM analyses clearly demonstrate that secondary hydration occurred. The RBRCA samples were able to maintain their unbound granular properties, with nonsignificant self-cementing, thus supporting the hypothesis that the mixing of nonactive materials such as bricks and clean rubble into RCA will lessen the tendency of RCA toward self-cementing

Handbook of Alkali-Activated Cements, Mortars and Concretes

This book provides an updated state-of-the-art review on new developments in alkali-activation. The main binder of concrete, Portland cement, represents almost 80% of the total CO2 emissions of concrete which are about 6 to 7% of the Planet's total CO2 emissions. This is particularly serious in the current context of climate change and it could get even worse because the demand for Portland cement is expected to increase by almost 200% by 2050 from 2010 levels, reaching 6000 million tons/year. Alkali-activated binders represent an alternative to Portland cement having higher durability and a lower CO2 footprint. Reviews the chemistry, mix design, manufacture and properties of alkali-activated cement-based concrete binders. Considers performance in adverse environmental conditions. Offers equal emphasis on the science behind the technology and its use in civil engineering

Investigation of hard-burn and soft-burn lime kiln dust as alternative materials for alkali-activated binder cured at ambient temperature

Copyright © 2020 The Author(s). As climate change becomes a severe concern, the development of green technology becomes a goal for many sectors, including the construction material sector. Ordinary Portland cement (OPC), the main constituent of concrete production, is a primary contributor to releasing carbon dioxide (CO2) into the atmosphere. Some alternative cementitious materials have been studied to reduce the massive amount of OPC consumption. Lime kiln dust (LKD), a by-product of quicklime production, is produced in abundance worldwide and mostly disposed of in landfills. The two types of LKD, soft-burn and hard-burn, are high-potential wastes that can be developed as alternative cementitious binders using the alkali-activated binder (AAB) technology. This study investigates the mixture designation and properties of LKD-based AAB when cured at ambient temperature. The results show that an ambient-cured soft-burn LKD-AAB achieved practical workability with an 8 M NaOH solution, 1.50 of sodium silicate-to-sodium hydroxide ratio (SS/SH), and 0.60 of liquid alkaline-to-binder ratio (L/B). A rapid setting behavior and an excellent compressive strength of 10.89 MPa at 28 days were revealed at room temperature curing. The ambient-cured hard-burn LKD-AAB could not provide the appropriate properties. However, the mixture of 20% hard-burn LKD and 80% soft-burn LKD resulted in an LKD-AAB mixture that meets the minimum requirement for low-strength cement applications. The positive outcome of this study may be the solution for of LKD wastes utilization in Thailand that addresses the challenge of developing ambient-cured AAB for in-field applications.Partially supported by Chiang Mai University; the fifth author would like to acknowledge the financial support of the Thailand Research Fund (TRF) under the TRF Distinguished Research Professor Grant No. DPG6180002; financial support and the raw materials for these experiments from Chememan Public Company Limited, Thailand

Laboratory-grade vs. industrial-grade NaOH as alkaline activator: The properties of coal fly ash based-alkaline activated material for construction

Case study.Data Availability: Data will be made available on request.Copyright © 2023 The Author(s). Alkaline-activated materials (AAM) are potentially low-carbon alternative binders for the cement industry. Most research studies related to AAM have been performed with high-purity laboratory-grade NaOH alkaline activators (Lab-grade). Gaining confidence in AAM beyond the laboratory scale in real applications remains a major challenge. To make this prospect more realistic, the viability of low-purity industrial-grade (Ind.-grade) and local no-grade alkaline activators was investigated. The strength results of Ind.-grade AAM were 15–20% lower than those of Lab-grade AAM. The purity of the Ind.-grade activator should be at least 98% to achieve the performance of Lab-grade AAM. The production cost of Ind.-grade AAM was 75–85% lower than that of Lab-grade AAM at the same activator concentration. It should be noted that the use of no-grade NaOH is not recommended for engineering purposes due to its uncertain quality and low purity. The combined benefits of low cost and high availability of Ind.-grade activators are expected to enhance the commercial viability of AAM as a sustainable alternative construction material for field applications.This work (grant no. RGNS 63–078) was supported by the Office of the Permanent Secretary, Ministry of Higher Education, Science, Research and Innovation (OPS MHESI), Thailand Science Research and Innovation (TSRI). Furthermore, this research work was partially supported by Chiang Mai University. The authors would like to express gratitude to the Department of Civil Engineering, Faculty of Engineering, Chiang Mai University (CMU), for providing equipment and facilities, as well as Mr. Witthawat Moonnee (M.Eng) who was working hard on this project. Special thanks to the cooperation of Brunel University London, UK and Imperial College London, UK. The last author would also like to acknowledge the support from the Research and Graduate Studies, Khon Kaen University

Influence of ammonia-contaminated fly ash from selective catalytic reduction process on the properties of Portland-fly ash blended cement and geopolymer composites

Data availability: Data will be made available on request.Fly ash, a by-product of coal-fired power plants, finds valuable application in the cement and concrete industry due to its pozzolanic properties. Environmental concerns necessitate the use of Selective Catalytic Reduction (SCR) systems to reduce nitrogen oxide emissions; however, this process introduces residual ammonia onto the fly ash, known as SCR-fly ash, which may affect its properties. This study investigates the characteristics and suitability of SCR-fly ash as a supplementary cementitious material in Portland cement and geopolymer cement composites, compared to conventional high-calcium fly ash. The results show that Portland-fly ash blended cement mixtures containing 20% SCR-fly ash achieve comparable engineering properties to those with high-calcium fly ash, with a slight reduction in compressive strength of ~3.4% at 28 days. Geopolymers with SCR-fly ash exhibit a significantly lower (~52.8%) compressive strength than that of high-calcium fly ash 28 days. However, SCR-fly ash requires a resting period of at least 20 days to reduce ammonia content before use. The larger particle size and presence of residual ammonia can react to form detrimental gypsum or ammonium salts that lead to reduced strength. Therefore, SCR-fly ash may need to be chemically treated to be suitable as a geopolymer precursor. Overall, this work provides crucial insights into the potential utilization of SCR-fly ash in the cement and concrete industry, promoting resource recovery and environmental sustainability.This research work was supported by Fundamental Fund 2025, Chiang Mai University. The authors would like to express their gratitude to the Department of Civil Engineering, Faculty of Engineering, Chiang Mai University, for providing the necessary equipment and facilities. Special thanks are due to Mr. Teerapad Jongwijak (M.Eng) for his dedicated efforts on this project. Thanks to the Electricity Generating Authority of Thailand (EGAT 68-N402000-11-IO.SS03N3008692) for their kind support