Jolius Gimbun

Permeable concrete is a type of concrete that allows water to flow through its internal matrix. These concretes are designed to manage stormwater runoff by assisting infiltration of rainwater into the ground. As such, these concretes are often viewed as the material of the future to construct climate-resilient infrastructures aligned with United Nations Sustainable Development Goal 11, Sustainable Cities and Communities. Recent concrete research reveals a novel type of binder, known as geopolymer cement or alkali-activated cement, which is reported to use no cement while having the same binding and hardening properties as cement. The discovery of this binder material led to an upsurge in studies looking to incorporate this concrete technology into permeable concrete to create green, eco-friendly, sustainable, and resilient infrastructures. Therefore, this book chapter looks to review the geopolymer technology and some of the research advancements in the utilization of these green solutions for use as permeable concrete applications. At the end of the book chapter, the author reveals some gaps in the study identified from the reviewed studies and recommends a material that can be utilized in geopolymer concrete research.

This study examines gas–liquid stirred tanks using Rushton‐type and long‐armed pitched paddle (LAPP) impellers at 0.35–1.1 VVM. Particle image velocimetry revealed up to 42% reductions in turbulent kinetic energy and radial velocity at high aeration from bubble–liquid interactions. The LAPP achieved up to 41% higher mass transfer coefficients than the Rushton at similar P _g / V , showing superior energy efficiency. Aerated power draw and flow regime transitions were correlated with Froude and aeration numbers, and a generalized correlation for mass transfer coefficients was developed from P _g / V and aeration number. Results support improved design and scale‐up of gas–liquid reactors, emphasizing the benefits of advanced impeller geometries.

This paper elucidates potential of spent coffee grounds (SCG) to reduce cement usage in a cement mortar mix by studying SCG as partial cement replacement in mortar production. Surface morphology and elemental composition of SCG were characterised using scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy and X-ray fluorescence analysis. With limited research on SCG incorporation in cementitious systems, this work evaluates setting time, fresh properties, and mechanical performance of SCG cement mortar at replacement levels ranging from 0% to 10%. Mortar specimens were water cured for periods between 7 and 90 days, after which compressive and flexural strengths were assessed. Optimisation results indicated that mortar containing 1.48% SCG, cured for 78 days, achieved highest compressive strength of 34.17 MPa. Thermogravimetric analysis revealed increased calcium carbonate formation in SCG-modified mortar, with no significant changes to other hydration products, despite reduced cement content. Durability testing demonstrated lower strength loss in SCG mortar compared with conventional mixes. These findings indicate SCG incorporation enhances both strength and durability, supporting its application as a sustainable construction material aligned with United Nations Sustainable Development Goals, specifically Goals 9 (Industry, Innovation and Infrastructure), 11 (Sustainable Cities and Communities), and 13 (Climate Action).

This paper presents an optimization of bioethanol production from oil palm trunk sap (OPTS) fermentation. The OPTS was obtained from an old palm tree (30 years old), whereas ethanol fermentation was carried out using Saccharomyces cerevisiae. The sugar content in OPTS and fermentation mother liquor was determined using high-performance liquid chromatography (HPLC). The parameters such as initial pH, temperature, and agitation rate were optimised using response surface methodology (RSM) with rotatable central composite design (CCD). It was found that the highest yield of bioethanol (75.82%) was obtained at the initial pH (5.79), temperature (31.05 ºC), and agitation rate (164.38 rpm). The optimization model of OPTS fermentation to bioethanol developed in this work may provide useful guidance to obtain a high ethanol yield from OPTS.

This paper presents a finite-element model of the structural behaviour of reinforced concrete (RC) beams with and without openings externally strengthened with bamboo-fibre-reinforced composite (BFRC) plates. The simulation was performed using ABAQUS Unified FEA 2021HF8 software. The stress–strain relationship of the RC was modelled using a model code for concrete structures, whereas the concrete-damaged plasticity model was used to simulate concrete damage. The predicted crack pattern of the beams was comparable to that from experimental observations. The ultimate load-bearing capacity of RC beams in flexure was predicted with an error of up to 1.50%, while the ultimate load-bearing capacity of RC beams with openings in shear was predicted with an error ranging from 1.89 to 13.43%. The most successful arrangement for strengthening a beam with openings in the shear zone was to place BFRC plates perpendicular to the crack on both sides of the beam’s surface, which increased the beam’s original load-bearing capacity by 110.06% compared to that of the control beam (CB). The most effective method for strengthening RC beams in flexure is to attach a BFRC plate to the entire bottom soffit of the RC beam. This maximises the ultimate load-bearing capacity at the expense of the beam’s ductility.

Ordinary Portland Cement (OPC) is a crucial building component and a valuable strategic resource. The production of cement accounts for 5% to 10% of global carbon dioxide (CO₂) emissions. Over the years, many researchers have been studying ways to reduce the amount of CO₂ in the atmosphere caused by cement production. Due to its properties, biochar is found to be an interesting material to be utilised in the construction industry due to its effectiveness in CO₂ sequestration. Biochar is a solid residue created by the thermal breakdown of biomass at moderate temperatures (350–700 ℃) without oxygen or with a small amount of oxygen, sometimes known as bio-carbon. Biochar has a wide range of uses, including those for heating and electricity generation, cleaning flue gases, metallurgy, animal husbandry, agriculture, construction materials, and even medicine. The objective of this paper is to review the potential of biochar as a cementitious material by evaluating its physical, chemical, mechanical, and durability properties. Using biochar as a cementitious material makes it possible to conclude that cement production will be reduced over time by partial replacement, which will also promote and encourage sustainable development in the future.

The research on extracellular matrix (ECM) is new and developing area that covers cell proliferation and differentiation and ensures improved cell viability for different biomedical applications. Extracellular matrix not only maintains biological functions but also exhibits properties such as tuned or natural material degradation within a given time period, active cell binding and cellular uptake for tissue engineering applications. The principal objective of this study is classified into two categories. The first phase is optimization of various electrospinning parameters with different concentrations of HAP-HPC/PLA(hydroxyapatite-hydroxypropylcellulose/poly lactic acid). The second phase is in vitro biological evaluation of the optimized mat using MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) assay for bone regeneration applications. Conductivity and dielectric constant were optimized for the production of thin fiber and bead free nanofibrous mat. With this optimization, the mechanical strength of all compositions was found to be enhanced, of which the ratio of 70:30 hit a maximum of 9.53 MPa (megapascal). Cytotoxicity analysis was completed for all the compositions on MG63 cell lines for various durations and showed maximum cell viability on 70:30 composition for more than 48 hrs. Hence, this investigation concludes that the optimized nanofibrous mat can be deployed as an ideal material for bone regenerative applications. In vivo study confirms the HAP-HPC-PLA sample shows more cells and bone formation at 8 weeks than 4 weeks.