Optimum Mix for Pervious Geopolymer Concrete (GEOCRETE) Based on Water Permeability and Compressive Strength

The production of ordinary Portland cement (OPC) consumes considerable natural resources and energy, and it also affects the emission of a significant quantity of CO2 in the atmosphere. This pervious geopolymer concrete study aims to explore an alternative binder without OPC. Pervious geopolymer concretes were prepared from fly ash (FA), sodium silicate (NaSiO3), sodium hydroxide (NaOH) solution, and coarse aggregate (CA). The effects of pervious geopolymer concrete parameters that affect water permeability and compressive strength are evaluated. The FA to CA ratios of 1:6, 1:7,1:8, and 1:9 by weight, CA sizes of 5–10, 10–14, and 14–20 mm, constant NaSiO3/NaOH ratio of 2.5, alkaline liquid to fly ash (AL/FA) ratios of 0.4, 0.5, and 0.6, and NaOH concentrations of 8, 10, and 12 M were the pervious geopolymer concrete mix proportions. The curing temperature of 80 °C for 24 h was used. The results showed that a pervious geopolymer concrete with CA of 10 mm achieved water permeability of 2.3 cm/s and compressive strength of 20 MPa with AL/FA ratio of 0.5, NaOH concentration of 10 M, and FA:CA of 1:7. GEOCRETE is indicated to have better engineering properties than does pervious concrete that is made of ordinary Portland cement

Management and valorisation of wastes through use in producing alkali-activated cement materials

There is a growing global interest in maximising the re-use and recycling of waste, to minimise the environmental impacts associated with waste treatment and disposal. Use of high-volume wastes in the production of blended or novel cements (including alkali-activated cements) is well known as a key pathway by which these wastes can be re-used. This paper presents a critical overview of the urban, agricultural, mining and industrial wastes that have been identified as potential precursors for the production of alkali-activated cement materials, or that can be effectively stabilised/solidified via alkali activation, to assure their safe disposal. The central aim of this review is to elucidate the potential advantages and pitfalls associated with the application of alkali-activation technology to a wide variety of wastes that have been claimed to be suitable for the production of construction materials. A brief overview of the generation and characteristics of each waste is reported, accompanied by identification of opportunities for the use of alkali-activation technology for their valorisation and/or management

Deformation properties of recycled aggregate concrete

The use of recycled aggregate (RA) from construction waste presents some important environmental and construction engineering issues that need resolution. Using RA in concrete opens possibilities in the ways in which recycled materials can be used for structural applications; positively, it may be an important breakthrough towards sustainable development. The utilisation of recycled aggregate is an effective solution to the problem of possessing excess waste materials while simultaneously maintaining satisfactory concrete quality. The utilisation of waste construction materials should be related to the application of quality guarantee systems to achieve suitable product properties. A complete understanding of the characteristics of new materials is, therefore, extremely important so that its potential in applications can be thoroughly studied. This paper investigates the deformation of recycled aggregate concrete (RAC). The experimental work on RAC from different mix proportions, including replacement ratios of RA 0%, 30% and 100% and water-to-cement ratios at 0.35, 0.45 and 0.6 are investigated on deformation properties of RAC: shrinkage and creep. All mix proportions are fixed the aggregate-to-cement ratio at 4.50. Further research directions are also discussed

Influence of two commercial superplasticizers and a biopolymer on the performance of waste-based alkali-activated mortars

This case study chapter discloses experimental results regarding the joint effect of sodium hydroxide concentration, the use of two commercial superplasticizers (polycarboxylate and lignosulfonate), and a biopolymer on workability and compressive strength performance of alkali-activated mortars based on fly ash and waste soda lime silicate glass