## 1 Introduction
### BJPA and Curing Temperature as the Major Factors to Study  
The water-cement ratio (W/C) is the proportion of the weight of water to the weight of cement in concrete, which critically influences its strength. A lower W/C ratio enhances concrete strength [10]. This is because a lower water content for a given cement content reduces the capillary porosity of the hardened concrete, resulting in a denser and more robust structure [11]. Decreasing the water-cement ratio also significantly increases the compressive strength of concrete [12]. This increase occurs because reducing the distance between cement particles promotes greater hydration, lowering porosity and enhancing compactness and strength. Moreover, decreasing the water-cement ratio from 0.6 to 0.4 increased the compressive strength of concrete by approximately 40%. Hydration, the chemical reaction between cement and water, is significantly influenced by the curing temperature, which profoundly affects concrete strength [13]. As the curing temperature rises, the formation of calcium-silicate-hydrate (C-S-H) phases accelerates, speeding the hydration process and leading to a rapid increase in early-stage concrete strength. However, high curing temperatures can result in less ordered and less stable C-S-H, potentially compromising the concrete's durability and long-term mechanical properties [14]. Elevated temperatures may cause uneven internal structures, altering the distribution and interaction of hydration products such as calcium hydroxide, which affects overall strength and durability. High temperatures can lead to the decomposition of ettringite or its transformation into mono-sulphate, negatively impacting volume stability and long-term durability. Therefore, maintaining an appropriate hydration temperature is crucial for enhancing early strength while avoiding the adverse effects of excessive temperatures and thereby ensuring concrete longevity. Studies on BJPA are scant, but the literature supports the use of BJPA as a cement replacement. [PERSON] et al. [15] extracted a silica-aluminium nanocomposite from BJBA, and the compositional analysis and microanalysis results showed that this highly pure silica-aluminium nanocomposite could be used as a new type of environmentally friendly recycled material. [PERSON] [13] and [PERSON] [16] used BJPA as a cement mortar replacement and claimed that a large quantity of BJPA lowers its effectiveness as a cement replacement. Hence, materials similar to BJPA have been explored as cement replacements. For instance, [PERSON] [17] used waste paper sludge ash (WPSA) to replace cement and found that its composition was similar to cement. Furthermore, BJPA has been investigated for its pozzolanic activity for use as a cement binder. [PERSON] and [PERSON] [18] studied the calcination of recycled newsprint and paper sludge as a replacement material. [PERSON] et al. used BJPA and fireclay powder as the base material and alkali activator, respectively, to produce an inorganic polymer composite based on fireclay powder and joss paper (called gold paper in some articles) ash; the results showed that BJPA could be applied to inorganic polymers as a recycled waste material [1]. In their experiments, the GGBFS-based geopolymer, which has already been a cement-less concrete material, was further replaced with BJPA by 0%, 20%, 40%, 60%, 80% and 100%. Researchers are actively seeking ways to improve the shortcomings of BJPA as a cement replacement, particularly the decrease in compressive strength (CS). One possible strategy is managing the curing temperature. With an increase in the steam curing temperature, the speed of the cement hydration reaction increases. In addition, cement hydration is a heat-producing reaction, meaning that speeding up the hydration reaction boosts the short-term accumulation of hydration heat. Thus, the CS of the material can be enhanced at the early stage of the curing process. Hence, the CS in 3 days may be as high as that obtained with a 'non-vapoured' process in 28 days [19; 20].