## 1 Introduction
Generally, the drying shrinkage of AAS pastes has been found to be much higher than that of AAS mortars due to the presence of fine aggregate, which inhibits shrinkage. Furthermore, AASC exhibits lower water absorption and higher flexural strength compared to ordinary Portland cement. Notably, the referenced studies all concentrated on investigating the properties of solid AASC cubes, not hollow blocks, which are the subject of the current study. The conventional hollow concrete block is a large rectangular brick that is widely used in construction. Concrete blocks are typically made from cast concrete, i.e., Portland cement and aggregate (usually a type of small-sized gravel) with sufficient water content to produce the desirable mixture properties. In Chinese factories, these blocks are generally prepared by an auto-compaction machine under pressure and vibration, then placed in a steam curing room at a temperature of 60-80 \({}^{\circ}\)C for 1 day before being cured at room temperature for 28 days. The demand for hollow concrete blocks has increased and so has the total production of cement. Because the production of cement is responsible for a significant amount of pollution, the development of new materials for hollow concrete blocks is an essential subject of research. Alkali-activated slag concrete exhibit fast setting time and high early strength, and they can demould in short time, making them suitable for preparing AASCHB without high-temperature curing. Ceramsite and pottery sand, a kind of highly dimensionally stable aggregate, have been used as the aggregate for AASC, which can decrease the drying shrinkage due to the reduction of paste content [27; 28]. A previous study [29] demonstrated that AASC has good potential for application in unitized masonry, an industry in which small sizes and a controlled setting offer an ideal environment for packing optimization by mechanical compaction, which has been demonstrated to increase the strength and durability of soil cement, alkali-activated clays, and other aggregate blends [30]. Though researchers have studied the basic mechanical properties of AASC, no study has described the use of AASC with pottery sand (as a fine aggregate) and ceramics (as a coarse aggregate), both of which offer significant benefits for use in concrete blocks. Accordingly, the effects of the water-to-slag ratio, sand ratio, silicate modulus, and Na\({}_{2}\)O content on the compressive strength and drying shrinkage of AASC incorporating these materials were investigated in this paper to investigate the behavior of a new type of AASCHB. The outcome of this research is a new high-performance AASCHB that can be useful in practical construction while reducing the environmental impact of the construction industry. This study determined that the optimal AASC mix for hollow concrete blocks has a water-to-slag ratio of 0.35, a sand ratio of 0.64, a silicate modulus of 1.2, and a Na\({}_{2}\)O content of 8% for optimal workability, high compressive strength, and low drying shrinkage. The resulting AASCHB can be classified under strength grade of MU15 and has been determined to be appropriate for use as a load-bearing hollow concrete block.