This research incorporates sustainable materials such as ground granulated blast furnace slag (GGBS) and recycled waste glass (RWG) as cement and fine aggregate replacement respectively to produce green dry mix mortar paving blocks. The GGBS and RWG contents in the mortar paving block were optimised using the response surface methodology (RSM), considering the performances of the ultrasonic pulse velocity (UPV), flexural and compressive strengths, water absorption, and Cantabro loss. Life cycle assessment (LCA) was also conducted to evaluate the environmental impact of the optimised green mortar paving blocks. The RSM suggested that the paving block with optimum GGBS and RWG contents of 26.5% and 91.3%, respectively, could exhibit compressive strength of 36.5 MPa, which complied with the requirement for concrete segmental paving units (MA20). Excluding the mixes not fulfilling the MA20 requirement, the mix with 40% GGBS and 100% RWG exhibited the lowest values for the acidification potential (AP), global warming potential (GWP), photochemical oxidation (POCP), abiotic depletion potential for fossil fuel (ADPF), and water scarcity/strength ratio. Whereas, for eutrophication potential (EP) and abiotic depletion for elements (ADP (elements))/strength ratio, the mix with 100% RWG exhibited the lowest value. The optimised mix from RSM showed a similar performance as the two mixes.
Construction Materials , Industrial Waste , Industrial Waste/analysis , Construction Materials/analysis , Compressive Strength , Water/analysis , Environment
The main obstacle of using geopolymer as a construction repair material is its slow strength development rate, which is the most significant attribute of an early-age opening for traffic and striking-off formwork. Geopolymer technology has recently attracted huge interest as an alternative to traditional cementitious materials with low environmental impact. Thus, this study investigates the feasibility of developing an ultra-high performance geopolymer concrete (UHPGC) with the aim of achieving high early-age strength. For this purpose, UHPGC mixtures activated with different potassium hydroxide molarities and aluminosilicate material types were developed and examined being cured with different curing temperatures. The early strength and durability of the UHPGC after 8 and 24 h were investigated. Experimental results revealed that the optimal mix design of UHPGC corresponds to a KOH molarity of 16 M and a 30% silica fume content. Furthermore, former mixture cured at 100 °C gave superior 8 and 24 h early strength values of 79 and 134 MPa, respectively. Moreover, a superior interaction of slag, silica fume, and activator solution at early age for UHPGC is revealed by the microstructural characteristics examined by a field emission scanning electron microscope (FESEM) with energy dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy analysis, and thermogravimetric (TGA) techniques. It was also found that the compressive strength results and the results of the microstructure analysis are well coincided. The experimental results obtained in this study emphasize the feasibility of using developed UHPGC as an eco-friendly quick repair materials The development of one-part UHPGC as a quick, cost-effective, and high-strength product for all construction repair maintenance will lead to huge improvements in the structural capacity and durability of structural components.
The use of cement as a soil stabilization agent is one of the common solutions to enhancing the engineering properties of soil. However, the impact and cost of using cement have raised environmental concerns, generating much interest in the search for alternative materials to reduce the use of cement as a stabilizing agent in soil treatment. This study looked into limiting cement content in peat soil stabilization by using fly ash waste and polypropylene fiber (PPF). It focused on soil mechanical mediation for stabilization of peat with fly ash cement and PPF cement by comparing the mechanical properties, using unconfined compressive strength (UCS) and California bearing ratio (CBR) tests. The control (untreated) peat specimen and specimens with either fly ash (10%, 20% and 30%) and PPF (0.1%, 0.15% and 0.2%) were studied. Test results showed that 30% of fly ash and cement content displays the highest UCS and CBR values and gives the most reliable compressibility properties. On the other hand, UCS and CBR test results indicate optimum values of PPF-cement stabilizing agent content in the specimen of 0.15% PPF and 30% cement. Selected specimens were analyzed using scanning electron microscopy (SEM), and PPF threads were found to be well surrounded by cement-stabilized peat matrices. It was also observed that the specimen with 30% fly ash generated more hydration products when compared to the specimen with 100% cement content. It is concluded that the use of fly ash cement and PPF cement as stabilizing agents to limit the cement usage in peat soil treatment is potentially viable.
