Environmentally Friendly Pervious Concrete for Treating Deicer-Laden Stormwater: Phase II

In Phase I of this project, graphene oxide (GO)-modified pervious concrete was developed using coal fly ash as the sole binder. The primary objectives of Phase II of this project were (1) to evaluate the stormwater infiltration capacity of GO-modified fly ash pervious concrete; (2) to evaluate the durability performance of GO-modified fly ash pervious concrete using freeze/thaw and salt resistance testing methods; and (3) to use advanced analytical tools to fully characterize the GO-modified fly ash binder. Test results indicate different degrees of reduction in concentrations of possible pollutants in stormwater—copper, zinc, sulphate, chloride, ammonia, nitrate, and total phosphate. The incorporation of GO significantly improved the resistance of pervious concrete to freeze/thaw cycles and ambient-temperature salt attack. The specimens were examined using X-ray diffraction, which revealed that the mineralogy and the chemical composition of fly ash pastes differ considerably from those of cement pastes. Nuclear magnetic resonance was used to study the chemical structure and ordering of different hydrates, and provided enhanced understanding of the freeze/thaw and salt scaling resistance of fly ash pervious concrete and the role of GO

Development of durable “green” concrete exposed to deicing chemicals via synergistic use of locally available recycled materials and multi-scale modifiers

From the economic and social perspectives, the use of waste materials would not be attractive until their costs and quality can satisfy the construction requirements. In this study, a pure fly ash paste (PFAP) was developed in place of ordinary Portland cement paste (OPCP). This PFAP was prepared at room temperature and without direct alkali activation. The samples were prepared using only the as-received class C coal fly ash, water, and a very small amount of borax (Na2B4O7). On average, the PFAP featured 28-d compressive strength of about 36 MPa, and micro-nano hardness and elastic modulus 29% and 5%, higher than the OPCP, respectively. These mechanical and other properties of the PFAP make it a viable “green” construction binder suitable for a host of structural and non-structural applications. Advanced characterization of the raw material and PFAP pastes was employed to elucidate the hydration mechanisms of this “green” binder. The obtained knowledge sheds light on the role of class C CFA in the hydration process and may benefit the expanded use of various CFAs in cementitious materials

Effect of raw materials on the performance of 3D printing geopolymer: A review

Traditional construction materials such as cement products release a significant amount of carbon dioxide during their preparation and usage, negatively impacting on the environment. In contrast, 3D printing (3DP) with geopolymer materials utilises renewable and low-carbon emission raw materials. It also exhibits characteristics such as energy efficiency and resource-efficient utilisation, contributing to reduction in carbon emissions and an improvement in sustainability. Therefore, the development of 3DP geopolymer holds great significance. This paper provides a comprehensive review of 3DP geopolymer systems, examining the effect of raw materials on processability, including flowability and thixotropy, and microstructure. The study also delves into sustainability and environmental impact. The evaluation highlights the crucial role of silicon, aluminium, and calcium content in the silicate raw material, influencing the gel structure and microstructural development of the geopolymer. Aluminium promotes reaction rate, increases reaction degree, and aids in product formation. Silicon enhances the mechanical properties of geopolymer, while calcium facilitates the formation and stability of the three-dimensional network structure, further improving material strength and stability. Moreover, the reactivity of raw materials is a key factor affecting interlayer bonding and interface mechanical properties. Finally, considering sustainability, the selection of raw materials is crucial in reducing carbon emissions, energy consumption, and costs. Compared to Portland cement, 3DP geopolymer material demonstrate lower carbon emissions, energy consumption, and costs, thus making it a sustainable material

Application of Gene Expression Programming (GEP) for the prediction of compressive strength of geopolymer concrete

For the production of geopolymer concrete (GPC), fly-ash (FA) like waste material has been effectively utilized by various researchers. In this paper, the soft computing techniques known as gene expression programming (GEP) are executed to deliver an empirical equation to estimate the compressive strength of GPC made by employing FA. To build a model, a consistent, extensive and reliable data base is compiled through a detailed review of the published research. The compiled data set is comprised of 298 experimental results. The utmost dominant parameters are counted as explanatory variables, in other words, the extra water added as percent FA (), the percentage of plasticizer (), the initial curing temperature (), the age of the specimen (), the curing duration (), the fine aggregate to total aggregate ratio (), the percentage of total aggregate by volume (), the percent SiO2 solids to water ratio () in sodium silicate (Na2SiO3) solution, the NaOH solution molarity (), the activator or alkali to FA ratio (), the sodium oxide (Na2O) to water ratio () for preparing Na2SiO3 solution, and the Na2SiO3 to NaOH ratio (). A GEP empirical equation is proposed to estimate the of GPC made with FA. The accuracy, generalization, and prediction capability of the proposed model was evaluated by performing parametric analysis, applying statistical checks, and then compared with non-linear and linear regression equations

Geopolymer Mortar Derived From Wood Ash And Fly Ash With Sodium Silicate

Kajian eksperimen ini mempamerkan pembangunan mortar geopolimer beralkali rendah yang berasaskan abu kayu berkandungan kalsium tinggi (HCWA) dan abu arang batu (PFA) The experimental investigation presented the development of low alkalinity geopolymer mortar derived from high calcium wood ash (HCWA) and pulverized fuel ash (PFA

Evaluating lithium slag for geopolymer concrete: A review of its properties and sustainable construction applications

This comprehensive review paper evaluates lithium slag (LS) as a promising precursor for geopolymer concrete, focusing on its workability, strength, durability, and microstructure. In the context of sustainable construction, LS emerges as a vital alternative to conventional cementitious materials, primarily due to the environmental concerns associated with cement production, such as substantial greenhouse gas emissions and air pollution. Geopolymer technology utilizes alkali activators and aluminosilicate-rich materials, offers a reduced environmental footprint and shows comparable performance to traditional cement-based concrete. In particular, LS has gained attention for its potential as an aluminosilicate precursor material in geopolymer concrete. This review investigated the recent advancements in LS-based geopolymers, exploring various processing techniques like mechanical activation, calcination, and chemical treatment to optimize LS geopolymerisation and enhance early strength development. The incorporation of binary/ternary aluminosilicate material is also discussed, aiming to improve crucial properties such as workability, strength, durability, and microstructure. The needs for comprehensive research into LS-based geopolymers to achieve their full potential in sustainable construction, promoting an environmentally friendly approach and contribution to a circular economy in the construction industry are highlighted

Strength and Chemical Characterization of Ultra High-Performance Geopolymer Concrete: A Coherent Evaluation

The objective of this review article is to analyze published data encompassing compressive strength, tensile strength, elastic modulus, and flexural strength, as well as the utilization of scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDS), and x-ray diffraction (XRD) for Ultra High-Performance Geopolymer Concrete (UHP-GC), with the focus of establishing the current research trends regarding its mechanical, microstructural, and chemical characteristics. After a critical evaluation of the published data from the literature findings, it became evident that UHP-GC can attain a remarkably high level of engineering performance. In UHP-GC, the optimum percentage of silica fume as a slag partial replacement to achieve high compression, tensile, and elastic modulus were traced to be 25, 30, and 35%, respectively. The optimum ratio of sodium silicate to sodium hydroxide and sodium hydroxide molarity for UHP-GC were identified to be 3.5 and 16, respectively. All in all, the review provides a thorough understanding of the review gap and distinct functions of different raw materials in decreasing porosity and enhancing the formation of geopolymeric gels that not only bond but also strengthen UHP-GC. UHP-GC stands as an energy-saving material in concrete technology, poised to forge a path towards a sustainable future for the building sector. Doi: 10.28991/CEJ-2023-09-12-020 Full Text: PD

Ceramic Waste Powder as a Partial Substitute of Fly Ash for Geopolymer Concrete Cured at Ambient Temperature

The growth of the construction industry has expanded the demand for ceramic building products such as ceramic tiles, which constitute essential building materials. Nonetheless, a huge quantity of waste powder is produced during the polishing of ceramic tiles. The disposal of ceramic waste powder is a key environmental concern that needs to be properly addressed. The purpose of this research is to evaluate the potential of recycling ceramic waste powder as a geopolymer binder. The main objective consists of exploring the impacts of two types of ceramic waste powder (vitrified tiles and wall tiles) on the partial substitution of fly ash in geopolymer concrete. For this, concrete was prepared under ambient conditions without oven curing. Slump, compressive strength, split tensile strength, and modulus of elasticity tests were performed to measure the workability and the mechanical properties of the geopolymer concrete. Its durability was evaluated through water absorption and sorptivity tests. The microstructural behavior was investigated using scanning electron microscopy and X-ray diffraction measurements. The investigation revealed that a 15% partial replacement of fly ash by wall-tile ceramic waste powder in geopolymer concrete gave similar compressive strength, a 3% increase in tensile strength, and a 7% improvement in the modulus of elasticity. Partial replacement of fly ash with 15% vitrified ceramic waste powder reduced sorptivity and improved the microstructure of geopolymer concrete. The findings revealed that ceramic waste powder can be used to replace 10–15% of the fly ash in M35 grade structural geopolymer concrete, which can be cured under ambient conditions. Doi: 10.28991/CEJ-2022-08-07-05 Full Text: PD

Proceedings of the 4th International Conference on Service Life Design for Infrastructure (SLD4)

SLD4 is a conference on Service Life Design for Infrastructures which is jointly organised by Delft University and Tongji University as part of the RILEM week 2018 in Delft, The Netherlands. The conference builds on the success of the previous three events on this topic held in Shanghai (2006), Delft (2010) and Zhuhai (2014). Service Life Design for Infrastructure is a very broad topic involving aspects starting from the material properties and behaviour, via structural performance, serviceability and durability to integral design and asset management. All related topics from experimental research to modelling and from codes and standards to applications are welcomed to the conference. The conference consist of 3 key-note papers and 132 regular papers presented over 3 days. Parallel to the SLD4 Conference a symposium on Concrete Modelling (CONMOD2018) and a workshop honouring Professor Klaas van Breugel were organised with topics that are related to Service Life Design. In total more than 350 participants took part in the events organised during the RILEM week 2018