The manufacturing process of geopolymer cement generally uses alkaline solutions mixed with alumina-silicate prime materials to form a cement paste. Other factors may be set up for the designated experiment, e.g., material constituents, activator’s concentration and curing regimes. One of the latent factors influencing the properties of geopolymer, which has received less attention, is a mixing method. General mixing and separate mixing processes, which have been previously studied, were synthesized as controlled procedures and compared with another alternative new mixing method called the pre-dry mixing process. The results have shown that the pre-dry mixing process provided high potential heat liberation, which could prove beneficial for curing purposes. It is confirmed that the proper mixing order leads to better results, especially for any of the alkaline-activated cementitious binders. With more practicality in field application, by just adding water, this process could be developed and applied in ambient temperatures.

Natural (hemp) fibers can be used in the cementitious composite as they have superb engineering properties, e.g. environmentally friendly and offer economic advantages. However, alkaline treatment (alkalization) process of natural fiber prior to mixing is required to modify fiber surface, making fibers more adhesive and compatible with cement paste. Geopolymer, one of the green alternative cementitious materials, is fortuitously involved in the alkaline environment, as alkaline solutions are used as its activators. The latent benefit, regarding the influence of alkalinity in geopolymer systems, namely ‘self-treatment process’ was thus investigated. The self-treatment process is a ‘Just-adding’ of as-received hemp fibers into geopolymer mixture without any pre-alkaline treatments. The results showed that the self-treatment process was governed by the alkaline environment in the geopolymer system and alternatively acted as an alkaline treatment condition for natural fibers, indicated by SEM and FT-IR analysis. The pre-alkalization process can be skipped in the self-treatment approach with similar mechanical properties to the ordinary processes. The main findings of this work could be further tailored to partially or fully the conventional alkaline treatment process and provide an opportunity for any other natural fiber geopolymer composites to be easily utilized in massive amount and used in practical applications.

Global warming is a vital issue addressed to every sector worldwide, including the construction industry. To achieve the concept of green technology, many attempts have been carried out to develop low-carbon footprint products. In the construction sector, Autoclaved Aerated Concrete (AAC) has become more popular and been manufactured to meet the construction demand. However, errors from manufacturing process accounted for approximately 3 to 5% of the AAC production. The development of AAC waste as lightweight aggregate in concrete is one of the potential approaches which was extendedly studied in this paper. The results showed that the compressive strength of AAC-LWA concrete was decreased with an increase in volume and coarse size. The optimum mix proportion was the AAC aggregate size of 1/2′′ to 3/8′′ with 20 to 40% replacement to normal weight aggregate. Internal curing by AAC-LWA was also observed and found to provide sufficient water inside the specimens, leading to an achievement in higher compressive strength. The main goal of this study is not only utilising unwanted wastes from industry (recycling of waste materials) but also building up a new knowledge of using AAC-LWA as an internal curing agent as well as the production of value-added lightweight concrete products.