is research focuses on developing a mix design methodology for alkali-activated high-calcium fly ash concrete (AAHFAC). High-calcium fly ash (FA) from the Mae Moh power plant in northern ailand was used as a starting material. Sodium hydroxide and sodium silicate were used as alkaline activator solutions (AAS). Many parameters, namely, NaOH concentration, alkaline activator solution-to-fly ash (AAS/FA) ratio, and coarse aggregate size, were investigated. e 28-day compressive strength was tested to validate the mix design proposed. e mix design methodology of the proposed AAHFAC mixes was given step by step, and it was modified from ACI standards. Test results showed that the 28-day compressive strength of 15-35 MPa was obtained. After modifying mix design of the AAHFAC mixes by updating the AAS/FA ratio from laboratory experiments, it was found that they met the strength requirement.

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The use of concrete in road construction has grown over the past decade due to the material’s great durability. However, concrete has poor tensile strength, ductility, and energy absorption. This paper aims to investigate the utilization of plastic waste, namely polypropylene (PP), to create a novel fiber to enhance the engineering properties of fiber reinforced concrete (FRC), an eco-friendly concrete that can reduce environmental problems. The 28-day design strengths of 28 and 32 MPa were used in this study because the compressive strength requirements for concrete footpaths and pavement specified by Austroads and the Department of Highways, Thailand, were at least 25 and 32 MPa, respectively. The fiber (F) was a mixture of virgin PP and recycled PP (RPP). The study used F contents of 0.25, 0.50, 0.75, and 1% by weight of cement and PP:RPP ratios of 100:0, 75:25, 50:50, 25:75, and 0:100. The compressive strength, flexural strength, leaching, and CO2 emissions savings of FRC were evaluated. Improvements in the compressive strength, flexural strength, and toughness of the samples with F were observed in comparison to the control concrete samples for all design strengths. All mixtures met the compressive strength requirements for concrete footpaths, except for F contents of 0.75 and 1% and a PP:RPP ratio of 0:100. By contrast, the 32 MPa FRC samples with F contents of 0.25 and 0.5% and all PP:RPP ratios met the requirements for rigid pavement. From an environmental perspective, the heavy metal contaminants of the 32 MPa FRC sample were within the allowable limits for all mixtures. Regarding incineration disposal, the maximum CO2 emissions savings of 28 MPa and 32 MPa FRC with an F content of 0.5% and a PP:RPP ratio of 0:100 were 1.0 and 1.11 kg CO2-e/m3, respectively. This research will enable plastic waste, traditionally destined for incineration and landfill disposal, to be used as a sustainable fiber in the construction industry.

This paper presents the effects of sand to binder (S/B) ratio and sodium hydroxide (NaOH) concentration on setting time, compressive strength, and shear bond strength of fly ash (FA)-Portland cement (PC) geopolymer binder. Geopolymer binder is manufactured from FA and PC at the ratio of 90:10 by weight of binder. The liquid alkali solution used in this study are sodium hydroxide (NaOH) and sodium silicate (Na2SiO3) solutions. The Na2SiO3/NaOH ratio of 2.0, liquid alkali solution/binder ratio of 0.60, and curing at ambient temperature are fixed in all mixes. The differences in NaOH concentrations of 5, 10 and 15M and S/B ratios of 1.00, 1.25 and 1.50 has been investigated. Test results show that the differences of NaOH concentration and S/B ratio has an effect on setting time, compressive strength and shear bond strength of FA-PC geopolymer mortar. The setting time of mortars are obviously decreased with increasing of S/B ratio whereas the setting time of mortars are obviously increased with increasing of NaOH concentration. The compressive and shear bond strengths of mortars increase as increasing of both S/B ratio and NaOH concentration up to a threshold limit. The highest slant shear strength between Portland cement concrete substrate and FA-PC geopolymer mortar is found in the mortar with 1.25 S/B ratio and 10M NaOH concentration which gives 24.1 MPa.