# Meta-Analysis of the Performance of Previous Concrete with Cement and Aggregate Replacements
## 1 Introduction
Furthermore, PC pavement improves skid resistance by increasing the friction on the road pavement as water drains off. It also reduces transportation-related noise as the sound produced by the interaction between the vehicle tire and the pavement is absorbed by the interconnected pores [17]. In addition, its use can aid in the removal of harmful contaminants such as heavy metals from the stormwater, which would lead to the recharge of aquifers with water of better quality [19]. PC pavements exhibit a 22% lower carbon footprint as compared to conventional impervious counterparts made with cement and well-graded NA [4]. However, similar to regular concrete, the sustainability of PC can be further improved by partially or completely replacing cement and natural aggregates with more environment-friendly alternatives. Various materials such as mineral admixtures, artificial aggregates, and eco-friendly binders, among others, have been utilized to develop sustainable PC with satisfactory performance and properties [9; 20]. Some studies have focused on partially replacing cement with industrial wastes, i.e., supplementary cementitious materials (SCM) [6]. Other studies have completely replaced cement with alkali-activated inorganic binders in single, binary, or ternary geopolymers [21]. Similarly, artificial and recycled aggregates (RA) have also been investigated in the partial and complete replacement of NA in PC [6]. However, to realize the full potential of these two approaches, the combined replacement of cement and aggregates was also investigated to produce a PC with mechanical and hydraulic performance similar to that of a control mix made with cement and NA [21]. To improve the durability performance of PC, especially abrasion resistance and freeze-thaw resistance,several measures were taken, including the replacement of cement with cementitious materials or the addition of macrofibers [22]. In recent work, the combination of fly ash (FA)-based geopolymer PC with 100% RA exhibited higher mechanical properties and a more cohesive nature than OPC- and NA-based PC [5]. The replacement of cement and aggregates in PC with more sustainable alternatives has gained global attention over the last few years. Thus, a review of PC produced while replacing cement and aggregates is needed to guide future sustainable material applications. Accordingly, for the first time, this work aims to conduct a review of the state-of-the-art literature and a meta-data analysis of the impact of cement and/or aggregate replacement on the performance of the produced PC. The present study seeks to examine the materials used for cement and aggregate replacement in PC and review the properties that were measured to evaluate the mechanical, hydraulic, and durability performance of the produced PC (with and without replacement). A meta-analysis is conducted to deduce the feasible range of the replacement percentage for cement and aggregates in PC, either as single or combined replacements, and the number of materials used, considering single or binary replacements. The ability to replace cement and aggregates without compromising the mechanical and hydraulic properties is also investigated. The findings are meant to provide collective information on PC produced with cement and aggregate replacements and to help outline the lessons learnt and the way forward in using various alternative materials in PC pavement applications.