Worker’s safety hazards results in substantial number of accidents including injuries and fatalities at the construction projects. This case study aims to apply Building Information Modeling (BIM) principles to optimize workers' safety during the design phase of a high-rise residential building. The study objective is to develop a BIM model and analyze it against construction safety hazards in order to identify risks, fire weak spots, remove structural clashes and optimize the constructability. The research methodology involved preparing a BIM model using AUTODESK Revit and analyzing it with Solibri Model Checker and IFC based fire safety analysis using Revit. The findings revealed that BIM process optimization significantly reduced accidents due to fall hazards, electrocution, caught-in or between objects, fire hazards, slips, trips, and falls. The BIM process was advantageous in terms of safety compared to traditional construction methods and could help stakeholders address safety issues, clashes, project cost, and scheduling concerns.

This study introduces the concept of Bio-LC³ in which biomass waste is upcycled into sustainable ingredients in limestone calcined clay cement (LC³) by partially replacing cement. Specifically, rice husk ash, rice husk biochar, sawdust biochar and titanium dioxide (TiO₂)-coated sawdust were chosen as the partial replacement for Ordinary Portland Cement (OPC). 

The novelty of this study lies in, firstly, a high replacement rate of 5-15 wt% was applied to replace OPC with the abovementioned biomass waste. Secondly, Accelerated Carbon Curing was applied to these different types of LC³ so that we could evaluate the effects of the different waste on carbon mineralization, strength, water absorption and thermal stability of LC³. 

It was found that it is possible to replace 15 wt% of cement with rice husk ash or 5 wt% of cement with TiO₂-coated sawdust and achieve similar compressive strength to that of carbonated LC³ control, which was in turn significantly stronger than LC³ control without carbonation. Carbonating LC³ with TiO₂-coated sawdust enhanced the reaction between mineralized carbonates (calcite) and metakaolin. In contrast, carbonation of sawdust biochar reduced calcite-metakaolin and metakaolin-Portlandite (CH) reactions, thus lowering its 28-day strength. Presence of rice husk biochar enhanced capture of carbon, as well as the overall bulk thermal stability.

All in all, these results showed that it is possible to further increase the sustainability of LC³ by valorizing different types of bio-waste and develop special functions that enhance the overall usefulness of these sustainable materials.

This talk is a sharing of a chapter in the recent book entitled “Biochar for Environmental Management - Science, Technology and Implementation” [1]. Focusing on the application of biochar in buildings and roads, it is more than just a review of the state-of-the-art in this aspect of biochar but aims to develop the fundamental principles and frameworks to understanding why and how biochar has the observed effect on concrete and asphalt. 

This talk is divided into two segments. In the first, the overall principles on how biochar results in positive effects on concrete or asphalt is illustrated - in essence, this can be attributed to biochar's influence on the hygro-mechanical properties of these construction materials by modifying their microstructure as a result of changing the moisture distribution in them. 

In the second segment, attention will be focused on the applications of biochar in concrete and asphalt. Specifically, the ways in which the filler effect, particle size, particle shape, macro- and micro-porosity, permeability, and the “reservoir effect” afforded by biochar modifies the moisture distribution in the concrete and asphalt media will be discussed. With this understanding as a background, a number of case studies on biochar concrete and asphalt research around the world will be shared. 

Finally, a few key areas of future development will be discussed - including the use of biochar to augment carbon mineralization in curing green concrete, such as limestone calcined clay concrete. 

Vanadium-bearing shale tailing is a type of solid waste with high silicon content. Due to high storage capacity, high production capacity, and low utilization rate, Vanadium-bearing shale tailing needs to be thoroughly studied to achieve resource utilization. [1] Alkali activated two-part geopolymer is a new type of inorganic polymer material made from aluminosilicate minerals. Due to environmental-friendly, excellent mechanical properties, and advantages in immobilizing heavy metals, geopolymer is the most promising inorganic polymer material to replace traditional Portland cement. [2] However, two-part geopolymer synthetic raw materials include two parts: alkali activator solution and active aluminosilicate powder. [3] The potential safety risks and operational difficulties of high concentration and high alkalinity alkaline corrosive activator solutions may limit the application of geopolymer. Therefore, researchers propose using solid alkali activators to prepare one-part geopolymer. [4] The chemical composition of Vanadium-bearing shale tailing indicates that it is suitable for synthesizing silicate based solid alkali activator.

There has been extensive research on the preparation of alkali activators from industrial solid waste, and the preparation methods can be mainly divided into three categories: fusion, hydrothermal, and thermochemical. [5] This study used thermochemical method to treat Vanadium-bearing shale tailing to prepare solid alkali activator. Then, the solid alkaline activator activates the metakaolin to synthesize one-part geopolymer.

XRD, Raman, and pH tests were used to analyze the significant effects of reaction temperature and sodium hydroxide dosage on the phase composition and activation effect of solid alkali activators. When the thermochemical activation temperature are 1073.15 K ~ 1273.15 K, the ratio of sodium hydroxide to Vanadium-bearing shale tailing are 90% ~ 100%, and the ratio of solid alkali activator to metakaolin are 66.7% ~ 100%, the compressive strength of one-part geopolymer is above 40 MPa. The main silicate phases of solid alkali activators are sodium silicate. XRD, SEM-EDS, Raman and NMR analyses indicate that sodium silicate mainly plays a role in alkali activation, and sodium silicate can be used as one-part geopolymer silicate raw material. 

The one-part geopolymer synthesized by alkali activator from Vanadium-bearing shale tailing has excellent compressive performance. Solid alkali activator can replace commercial sodium silicate as a cost-effective and environmental-friendly to prepare one-part geopolymer.

The quality and functional properties of any material, including composite systems, are determined by their phase composition and structural characteristics. One of the effective methods of influencing and regulating the level of activity of the system is mechanochemical treatment (MCT) of powder systems, which allows changing their degree of dispersion, defectiveness and forming highly active formations on the surface of particles [1]. The role of surface structures is extremely important in the creation of modified powder materials with a given set of properties. 

Modification of mineral powder particles directly during the grinding process is one of the areas of mechanochemical processing of inorganic materials [2, 3]. Mechanochemical processing will allow purposefully changing the state and chemical activity of the mineral components of the charge mixtures. 

The work involved studies on obtaining SHS heat insulators with pre-activated raw materials. Experimental work was carried out using natural mineral raw materials - grade "A" calcined diatomite crumb (fraction 0-0.2 mm). During preliminary mechanical activation, graphite was used as a modifier in the amount of 10 and 20%. Aluminum grade APV was used as a reducing agent. Sodium liquid glass served as a binder.

A positive effect of using various modifiers during the MCT of diatomite, activating the combustion process, was established. The selection of modifiers provides an increase in the strength of the synthesized SHS composites as a result of the formation of aluminate compounds in the synthesis products and a decrease in thermal conductivity to 0.157 W/m*K due to the formation of an ultraporous structure of the samples.

Limestone calcined clay cement (LC3) is a sustainable binder that has been increasingly studied as an alternative to Ordinary Portland Cement (OPC). However, one of the technical barriers to large scale application of LC3 is its low workability. Although the creation and application of tailored superplasticizers (SPs) has become one of the most common solutions to this problem, the over-reliance on such chemicals will give rise to other problems, including high embodied energy in these SPs.

This study aims to offer a more sustainable solution by valorizing abundant waste wood, in the form of biochar, to replace 2wt% and 10wt% of OPC content in LC3; this is done to increase the overall sustainability of the LC3, while increasing compressive strength, shortening setting times and improving workability. To ensure that our results are relevant to actual construction conditions, all samples were subjected to air-curing.

It was found that all LC3 that contained biochar were significantly stronger than OPC control at 28 days. In particular, incorporating 2wt% biochar (dry or pre-soaked) could maintain compressive strength of the LC3 but yield significant better workability than OPC mortar. 

A model was proposed to explain this phenomenon - specifically about how biochar modifies the water distribution by reducing the amount of gel pore water and at the same time, increasing the amount of free or bleeding water available when the LC3 samples were mechanically agitated; this enhances the movement of particles over one another during mixing or vibration, thus lowering the viscosity and improving the workability. 

In summary, these results can potentially point the way to improving the sustainability of LC3 while reducing wood waste, using biochar as a pathway to waste valorization in the creation of high-performance concrete.

Soft soils provide the difficult ground conditions for construction and are characterized by low unconfined compressive strengths (<50 kPa) [1]. This study evaluated the performance of pyrolytic biochar (PBC) derived from industrial wastewater sludge in soft soils to enhance their unconfined compressive strength. Also, investigating the mechanism behind strength development was focused on. Different amounts of PBC (0%, 5%, 7.5%, 10%, and 12.5% by weight) were mixed with the soft soil, and the unconfined compressive strength (UCS) values were measured after curing periods of 1, 7, 14, and 28 days. The UCS values increased by approximately 4-5 times, while the stiffness values increased by around 5-6 times. Adding PBC also increased the alkalinity and water-holding capacity of the soil-PBC matrices, promoting pozzolanic reactions [2]. The free calcium oxide (CaO) in PBC disrupted the laminated soil structure and reacted with silica oxides (SiO₂) and other aluminum silicates, resulting in a denser soil-PBC structure and the formation of Tobermorite, a hydrate mineral of calcium silicate [3]. Overall, the study concluded that PBC has the potential to be an effective alternative to traditional soil stabilizing materials, as it improves the unconfined compressive strength of soft soils.

In response to the accelerated pace of urbanization and the steady rise in global population, a palpable consequence has manifested - a striking surge in CO2 emissions, emerging as the foremost catalyst behind climate change. Concrete, as one of the most widely used materials in the world aside from water, forms the foundational framework of modern society. However, the production of concrete contributes to 8% of anthropogenic carbon emissions. Despite efforts to reduce these emissions through passive strategies like decreasing clinker content, using local resources, and efficient design, the reduction levels have been limited. Consequently, CO2 emissions from the construction sector have peaked post-pandemic. This talk presents an active carbon reduction strategy for sustainable construction to tackle this challenge. This innovative approach transforms concrete into a carbon sink by utilizing CO2 at different stages of the concrete's lifecycle. Initially, CO2 acts as an activator or rheology modifier, improving the fresh properties of concrete. In the middle stages, CO2 serves as a curing agent, enhancing strength and durability through carbonation curing technology. In the later stages, CO2 functions as a surface enhancer, densifying the concrete's outer surface. This strategy also incorporates major urban solid wastes, such as incineration bottom ash, waste glass, and waste concrete, as precursors in the concrete production process.