Analytic Hierarchy Process–Based Evaluation and Experimental Assessment of the Optimal Interlocking Compressed Earth Block Geometry for Seismic Applications

Abstract

Interlocking Compressed Earth Blocks (ICEBs) offer a sustainable alternative to conventional fired-clay bricks but remain hindered by inconsistent geometric designs and limited standardization. This study develops a stakeholder-weighted Analytic Hierarchy Process (AHP) framework to evaluate and select the most suitable ICEB geometry for sustainable and seismic-ready construction in developing regions. Five evaluation criteria—size, weight, interlocking effectiveness, reinforcement/grout provision, and handling ergonomics—were prioritized based on expert input from masons, engineers, architects, and researchers. The synthesized results ranked the HiLo-Tec-type geometry highest, followed by Thai-Rhino, Auram, and Hydraform designs. Unit weight (0.289) and reinforcement capacity (0.261) emerged as dominant decision factors. Sensitivity analysis confirmed the robustness of rankings under varying weight perturbations. The AHP framework identifies the top-ranked geometry, whose structural performance was examined experimentally through a full-scale cyclic test on a grouted double-wythe ICEB wall, revealing enhanced ductility and residual strength compared with traditional brick masonry. The proposed framework demonstrates that selected ICEB geometry can balance ergonomic and structural performance while meeting seismic resilience demands. Beyond geometry selection, the model provides a replicable decision-support tool adaptable for regional material innovations in sustainable construction.

1. Introduction

The construction industry is facing increasing pressure to minimize its environmental impact while delivering affordable and resilient housing. Conventional fired-clay brick manufacturing is one of the most energy and carbon-intensive construction methods, contributing approximately 2.7% of the annual global CO₂ emissions [1,2]. The environmental and social consequences of kiln-based manufacturing have led to an urgent need for low-carbon alternatives in developing nations, which account for approximately 90% of global brick production. Earthen construction techniques, including adobe, rammed earth, cob, and Compressed Earth Blocks (CEBs), have resurfaced as effective alternatives due to their utilization of locally sourced soil, low energy requirements for production, and their capacity for thermal comfort and durability [3,4]. ICEBs are a modern variant of earthen masonry that incorporates mechanical interlocks, facilitating mortar-free construction, expedited assembly, and minimized material waste [5,6,7].

Despite these numerous advantages, the widespread adoption of ICEBs is hindered by inconsistent geometric design and a lack of standardization. Various block geometries are present, including Hydraform, Auram, Thai-Rhino, and HiLo-Tec, each characterized by distinct size, mass, interlock configuration, and reinforcement features [8,9]. Geometry significantly affects structural and ergonomic performance; larger or heavier blocks can expedite wall assembly but may also lead to increased worker fatigue [10], whereas blocks with insufficiently sized cavities impede reinforcement and grout flow, which are critical for seismic safety [11]. The top-ranked geometry of ICEB must balance structural capacity, ergonomic handling, and constructability, considering local material and labor constraints, thus presenting a multi-criteria decision problem.

Previous studies have focused primarily on material composition or compressive strength [12,13,14], often neglecting the interplay between geometry, reinforcement, and worker ergonomics. Experimental or numerical prototyping approaches, though rigorous, are resource-intensive and impractical for iterative geometric evaluation. Furthermore, geometric designs are frequently adopted by other regions without considering differences in construction skills, tooling, or seismic demands. These limitations justify a structured decision-support framework that captures multi-criteria trade-offs and incorporates both technical and field-experienced perspectives before large-scale prototyping.

To address this gap, this study develops a stakeholder-weighted Analytic Hierarchy Process (AHP) framework to evaluate and rank four representative ICEB geometries (Hydraform, Auram, Thai-Rhino, and HiLo-Tec) that integrate practitioner-derived criteria: size, weight, interlocking effectiveness, reinforcement/groutability, and handling ergonomics. The framework aggregates judgments from masons, engineers, architects, and researchers to reflect realistic construction priorities in the resource-constrained and seismically active region. The top-ranked geometry with region-specific modifications is experimentally validated through full-scale cyclic testing of a double-wythe ICEB wall. The experimental part provides an objective, practical evidence of the AHP-driven decision. The study demonstrates that by combining these two methodologies, a geometry selected by field experts for its perceived suitability will ultimately yield the quantitative, high-stakes performance necessary for low-carbon construction in seismic regions. The proposed framework can bridge the gap between laboratory design and on-site constructability, facilitating the adoption of sustainable and seismically resilient masonry technologies in developing regions.

2. Research Methodology

2.1. Research Framework

This research follows a multi-stage sequential approach, as shown in Figure 1. To identify the most critical criteria for ICEB geometry evaluation, the first phase of the methodology involves conducting a comprehensive literature review. Afterwards, a diverse group of experts surveyed the pairwise comparisons for these criteria and the alternative block geometries. Subsequently, the AHP is used to synthesize these judgments, calculate priority weights, and rank the alternatives. A sensitivity analysis is performed to check the stability of the final ranking. The final selection was made based on ranking, and experimental confirmation of structural performance was achieved through full-scale cycle testing. This approach integrates expert judgment with hard data from experiments.

2.2. Case Study

This research is conducted as a case study focused on sustainable construction for developing regions that are also seismically active. The selection of experts (masons, engineers, architects, and researchers) from this context is deliberate to ensure the final priorities reflect on-the-ground field realities and labor constraints, rather than purely theoretical or commercial criteria. All AHP calculations for pairwise comparisons, priority vector synthesis, principal eigenvalue computation, and consistency checks were performed using Microsoft Excel 365.

2.3. Evaluation Criteria

The five evaluation criteria were established following a systematic literature review and consultation with practitioners. An extensive search was conducted in Scopus and ScienceDirect using the keywords “interlocking compressed earth block,” “geometry,” “constructability,” “ergonomics,” and “reinforced earthen masonry,” encompassing papers published from 2000 to 2024. A total of 73 articles were reviewed, of which 11 studies directly addressed ICEB/interlocking block geometry or performance. The criteria, including cost, material availability, and thermal insulation, were recognized but excluded due to their significant dependence on regional economics and material supply networks, rather than the geometry itself. The five maintained criteria thus signify the geometry-related and constructability-oriented aspects that most significantly influence seismic and ergonomic performance:

2.3.1. Size of ICEB

Size is a critical factor that governs wall modularity, construction speed, and joint density. A regular ICEB is a rectangular cuboid defined by its length, width, and height. Larger blocks cover a greater surface area, requiring fewer blocks and grouted or mortar joints per wall, which lowers material costs and speeds up construction [15]. Smaller block sizes have more units and joints per area, which may increase material consumption and labor time [16]. Proper selection of the ICEB geometric design is necessary due to the trade-off between block size, labor efficiency, material consumption, and ergonomics. The typical size of common ICEBs ranges from 250 to 400 mm in length, 127 to 220 mm in width, and 80 to 150 mm in height [9]. The specified sizes notably affect the block’s esthetic value and its compatibility with various architectural styles, underscoring the complex function of geometry in sustainable construction.

2.3.2. Weight of ICEB

The weight of materials directly influences the physical load on masons, thereby impacting construction productivity and safety [11]. Lifting frequency, height from which bricks or blocks are lifted and subsequently set, and distance from the worker are some of the risk factors found for back injuries among masonry workers [17]. Thus, the productivity of workers on the job site is directly affected by block weight. Masons become fatigued more rapidly by heavy blocks (>6–7 kg), which limits the number of units they can stack in a day [6]. Lighter blocks are much simpler to move and stack, resulting in a faster construction process with less back strain on workers. Size and material density have a direct impact on weight; for example, the inclusion of cavities in the block may reduce weight while still offering other advantages. The block weight should be manageable for single-handed grasping to improve mobility and operating efficiency in masonry construction [15]. This allows the mason to set blocks without stopping, keeping a steady workflow. Lightweight aggregates, such as expanded clay, glass, and other natural and recycled materials, can reduce the bulk density of ICEBs, thereby reducing the ergonomic load on workers and improving handling efficiency without compromising structural integrity [6,8,18].

2.3.3. Interlocking Capability of ICEB

An ICEB is specially designed with protrusions and extrusions that form a “mortise and tenon” joint, fitting together to provide mechanical embedding and easy dry stacking. The interlocking mechanism defines alignment accuracy and in-plane shear transfer between blocks. The geometric shape and size of these interlocking keys play a critical role in block alignment and ease of placement. From a structural perspective, the larger interlocking keys can enhance shear strength and contribute to both in-plane and out-of-plane stability [14,19,20]. However, larger interlocking keys would require a high level of manufacturing precision in low-tech or manual block production environments, where there is a risk of non-uniform compaction and other environmental factors that would cause inaccuracy in the size of interlocking keys. This outcome will cause misalignments during wall construction, and the courses may not be completely aligned horizontally if the interlocking key is not fabricated with sufficient accuracy [13]. In contrast, smaller or moderately sized keys may provide adequate interlocking while accommodating slight variations during the production process. Thus, reducing the physical exertion and time required from masons, offering minimal field adjustments if required, and enhancing their adaptability to real-world variations in block production and site conditions.

2.3.4. Reinforcement and Grout Feature of ICEB

The ability of the block to accommodate reinforcement typically involves vertical steel bars or cavities designed for grouting concrete. The addition of reinforcement notably enhances the structural capacity of masonry, especially under seismic and severe wind loads [10]. The reinforcing feature in ICEBs allows for flexibility in both seismic and non-seismic zones, accommodating reinforced and unreinforced wall construction. Steel rebars may be inserted through vertical holes or openings in specific ICEB systems, with the cores being grouted to facilitate composite action. Structurally, the cavity must accommodate vertical rebars with a diameter not exceeding one-eighth of the nominal wall thickness, or they must be small enough to allow at least a 12.7 mm clearance on all sides, ensuring proper grout flow and bond development as per TMS 402/602-16 [21,22]. Larger cavities enable effortless grout application, reduce the likelihood of air entrapment, and ensure complete bonding with reinforcement. This is particularly crucial when using common field mixes, such as 1:2:4 concrete with coarse aggregates (≤ 12.7 mm). Inappropriate fillings can occur when holes are misaligned or narrowed, which may compromise the structural integrity of the wall.

2.3.5. Ergonomics of ICEB

Ergonomics here refers to the general simplicity of lifting, carrying, positioning, and adjusting blocks, while construction directly influences construction speed and labor efficiency [23,24]. This criterion considers factors such as surface texture and grip characteristics to enhance ease of handling, minimize slippage, and ensure stable placement during masonry work. In addition to weight and size, particular design features significantly influence handling efficiency and user comfort. When the block is not high enough, it can be more readily grasped between the fingers, enabling improved control during placement, particularly in restricted or elevated positions. Additionally, corner geometry is another essential factor to consider; sharp or solid corners may chip hands during handling or cause discomfort, abrasions, or even minor injuries to the worker’s hands. However, blocks with beveled edges, slightly rounded corners, or recessed grip zones enhance safety and comfort, contributing to increased labor productivity [17].

2.4. Scope and Rationale of Selected Criteria

The five criteria established provide a comprehensive framework for evaluating the top-ranked ICEB geometry for sustainable construction in the resource-constrained or labor-intensive construction environments. This study primarily focuses on geometric and handling features. However, other factors, such as material properties or manufacturing processes, are acknowledged as necessary but are outside the scope of this specific geometric selection. Each selected criterion is essential to the functionality and constructability of the ICEB, thereby informing the selection of top-ranked ICEB geometry for sustainable construction applications.

3. AHP Framework

The AHP provides a systematic and transparent framework for prioritizing alternatives when decisions involve both quantitative and qualitative criteria. In this study, the AHP was applied to evaluate four candidate ICEB geometries against five field-validated criteria, as shown in Figure 2. The procedure followed Saaty’s (1980) method with additional checks for group consensus and ranking robustness to ensure decision reliability [25].

3.1. Decision Hierarchy

This study presents a decision hierarchy structured into three levels: the primary goal of selecting top-ranked block geometry based on five evaluation factors such as block size, weight, interlocking capability, reinforcement and grout features, and handling ergonomics relevant to their adoption in the construction industry of developing regions with four representative geometries—Hydraform, Auram, Thai-Rhino, and HiLo-Tec (see Figure 3).

Table 1. Summary of the four ICEB alternatives (A–D).

Alternative	Size (mm)	Weight (kg)	Interlocking	Reinforcement	Ergonomics	Keynote
A—Hydraform	240 × 220 × 115	10–12	Horizontal key (height ≈ 5–10 mm); alignment ridge only in bed joint	None	Solid body; no finger grip; heavy to lift, frequent trimming	Good mass and stiffness, but poor ergonomics; unsuitable for seismic reinforced walls
B—Auram	295 × 145 × 95	6–8	Groove-and-tongue interlocking key (height ≈ 9 mm)	1 small central core	Side grooves and chamfered edges enable better finger hold and safe placement	Easy to handle but limited rebar use; esthetic finish preferred for façades
C—Thai-Rhino	300 × 150 × 100	6–8	Dual keys (height ≈ 12 mm) providing a strong mechanical fit	2 cores + groove	Side grooves, chamfered	Secure interlock, good seismic fit, but reduced net area
D—HiLo-Tec	280 × 140 × 90	5–7	Dual circular keys (height ≈ 10 mm) for two-way interlock	2 full-height cores	Integrated finger grips, chamfered corners, lightweight, stable placement	Balanced design; ergonomically superior and reinforcement-ready

presents a summary of four representative ICEB geometries. This hierarchical arrangement breaks down the complex selection process into manageable pairwise comparisons, enabling experts to express their relative preferences systematically.

This study employed a single-level criterion structure to preserve clarity and consistency in expert evaluations, despite the ability of a multi-level hierarchy to encompass sub-criteria (e.g., cost under economy, strength under performance). Considering the practical competence of field masons and engineers, additional sub-levels may exacerbate cognitive inconsistency without enhancing decision-making value. Streamlined hierarchies are prevalent in AHP applications concerning physical product geometry [26].

3.2. Expert Judgments and Pairwise Comparison

Expert input was obtained from 26 professionals involved in masonry construction: 10 field engineers, 8 masonry workers, 4 architects, and 4 academic researchers specializing in masonry structures (Figure 4). Each expert completed a structured questionnaire, providing pairwise comparisons using Saaty’s 1–9 scale, as shown in

Table 2. Saaty’s Scale Table for AHP Pairwise Comparison.

Scale Value	Verbal Judgment of Preference	Explanation
1	Equal importance	Two variables contribute equally to the objective
3	Moderate importance	Experience somewhat advantages one variable over another
5	Strong importance	Experience judgment significantly favors a single variable
7	Very strong importance	Dominance of one variable is demonstrated in practice
9	Extreme importance	Evidence favors one element absolutely
2, 4, 6, 8	Intermediate values	Used when a compromise is needed between two adjacent judgments
Reciprocals (1/3, 1/5, etc.)	Inverse judgments	If element i is favored over j with a given scale, then j is valued at the reciprocal compared to i

, where 1 indicates equal importance and 9 denotes an extreme preference for one element over another.

The Aggregation of Individual Judgments (AIJ) approach was utilized to integrate individual assessments. The geometric mean of individual pairwise entries generated a consensus matrix for each criterion, reducing the impact of outliers and ensuring a balanced representation of stakeholder perspectives. The resulting 5 × 5 matrix represents the relative importance of the five criteria, while four 4 × 4 matrices evaluate the alternative blocks with respect to each criterion.

3.3. Consistency and Consensus Checks

The internal consistency of expert judgments was verified using the consistency index (CI) and consistency ratio (CR) proposed by Saaty (1980) [25], Equations (1) and (2).

$$CI={\displaystyle \frac{{\lambda }_{max}-p}{(p-1)}}$$

(1)

$$CR={\displaystyle \frac{CI}{RI}}$$

(2)

where $p$ is the size of the matrix, i.e., criteria (5 × 5) and alternatives (4 × 4). The consistency of all pairwise-comparison matrices was numerically verified following the procedure of Saaty (1980) [26]. The principal eigenvalue (λₘₐₓ), CI, and CR were calculated for the 5 × 5 criteria matrix and each of the 4 × 4 alternative matrices. As summarized in

Table 3. CI and CR for all pairwise-comparison matrices.

Parameter	Criteria-Level (5 × 5)	Size (4 × 4)	Weight (4 × 4)	Interlocking (4 × 4)	Reinforcement (4 × 4)	Ergonomics (4 × 4)
Matrix order (p)	5	4	4	4	4	4
Principal eigenvalue (λₘₐₓ)	5.45	4.15	4.13	4.19	4.2	4.18
Consistency Index (CI)	0.112	0.05	0.043	0.063	0.067	0.06
Consistency Ratio (CR)	0.091	0.056	0.048	0.07	0.074	0.066

, the main criteria matrix yielded λₘₐₓ = 5.45, CI = 0.112, CR = 0.091 (<0.10), confirming acceptable consistency [26,27]. All alternative matrices also satisfied Saaty’s threshold with CR values between 0.048 and 0.074, indicating stable expert judgments across all comparisons.

3.4. Sensitivity Analysis

Because AHP outcomes can shift with small variations in weight, a sensitivity analysis was conducted to evaluate ranking stability. Each criterion weight was perturbed by ±10%, ±20%, and ±30% to maintain normalization, and the resulting rankings were recalculated. The ±10%, ±20%, and ±30% envelopes follow AHP sensitivity practice for plausible judgment drift without inducing artificial rank reversals [26]. It spans modest to significant shifts often observed in heterogeneous expert panels. The procedure evaluates the robustness of the ranking and checks for the potential of rank reversal, ensuring it is not overly dependent on any single criterion.

4. Results

4.1. Criterion Prioritization

The aggregated pairwise comparison matrix (

Table 4. Aggregated Pairwise Comparison Matrix of Evaluation Criteria.

Criteria	Size	Weight	Interlocking	Reinforcement	Ergonomics	Normalized Weight (wᵢ)
Size	1	0.455	0.776	0.505	0.892	0.132
Weight	2.198	1	1.7	1.106	1.953	0.289
Interlocking	1.288	0.588	1	0.653	1.148	0.170
Reinforcement	1.981	0.904	1.531	1	1.763	0.261
Ergonomics	1.121	0.512	0.871	0.567	1	0.148

) was consistent (CR = 0.091 < 0.10), confirming the reliability of expert judgments. The normalized weights assigned to the five evaluation criteria are shown in Figure 5. The reinforcement/grout feature was found to be the most significant factor (0.289), followed closely by the block’s weight (0.261). Interlocking effectiveness was ranked third (0.170), while ergonomics (0.148) and overall block size (0.132) had less significant contributions to the final decision.

The practical logic that supports low-technology construction contexts in labor-intensive, resource-constrained, and seismically active regions is exemplified by this hierarchy. Structural practicality is crucial, as seismic performance and the integrity of the wall are directly influenced by groutability and reinforcement. Masons and site engineers prioritize the efficacy of lifting, positioning, and reinforcing blocks, as these factors have a substantial impact on safety and productivity. Geometric size is considered less significant because it indirectly intersects with weight and handling considerations. The results are consistent with the existing ergonomic and productivity research on masonry duties [17,28], emphasizing that worker fatigue and tool compatibility are substantial constraints in the field.

4.2. Ranking of Alternative Geometries

Using the computed criterion weights, local priorities for the four ICEB geometries were synthesized to obtain global scores (

Table 5. Synthesis of Local Priorities and Computed Global Scores for ICEB Geometries.

Criterion	Size (mm)	Weight (kg)	Interlocking	Reinforcement	Ergonomics	Weighted Global Score	Rank
Criterion Weight	0.132	0.289	0.17	0.261	0.148
Hydraform (A)	0.065	0.065	0.067	0.062	0.094	0.069	4
Auram (B)	0.473	0.349	0.144	0.168	0.227	0.266	3
Thai-Rhino (C)	0.155	0.215	0.571	0.314	0.343	0.312	2
HiLo-Tec (D)	0.306	0.37	0.218	0.456	0.336	0.353	1

and Figure 6). The HiLo-Tec block (Alternative D) attained the highest global priority score of 0.353, succeeded by Thai-Rhino at 0.312, Auram at 0.266, and Hydraform at 0.069. The prevalence of HiLo-Tec geometry is due to its balanced structural and ergonomic performance. The dimensions of approximately 280 × 140 × 90 mm result in a manageable weight of 5–7 kg, and the dual vertical cores facilitate the insertion of Ø12.7 mm rebars, ensuring complete grout flow. The moderate interlocking keys enable rapid alignment without the need for high-precision molds, thereby enhancing constructability in manual press production.

In contrast, the Hydraform block scored lowest due to its heavy solid profile (≈ approximately 10–12 kg) and lack of reinforcement provisions, which limit its usability in reinforced or seismic applications. The intermediate ranking of the Thai-Rhino and Auram geometries reflects a trade-off between interlocking stability and practicality of reinforcement.

Despite Auram and Thai-Rhino having almost similar physical sizes, their local priorities deviate due to Thai-Rhino’s incorporation of double interlocking knobs and larger groutable cores, which improve alignment and reinforcement flexibility. Auram’s single-core design restricts bar placement, revealing its diminished composite priority despite comparable size. This aligns with field evaluation, wherein Thai-Rhino’s interlock height and reduced net cross-section yield enhanced handling challenges and reduced modular flexibility, resulting in a somewhat lower normalized weight for size despite comparable nominal length. Although the Thai-Rhino block exhibits strong two-way interlock performance, its thicker webs reduce the effective grout area. The Auram design, while easy to handle and esthetically refined, includes only a single small core that restricts bar placement and grout flow. Overall, expert preference converged toward the geometry that maximized labor efficiency, reinforcement adaptability, and reduced physical strain.

4.3. Sensitivity and Robustness Assessment

To evaluate decision stability, a sensitivity analysis was performed on each criterion weight, varying it by ±10%, ±20%, and ±30%, while maintaining total weight normalization, as shown in Figure 7. Under Size perturbations, the global scores varied within ±0.004 for Auram and ±0.006 for Thai-Rhino, while HiLo-Tec remained 0.351–0.356, preserving rank 1. Under Interlocking +30%, Thai-Rhino briefly narrows the gap to 0.344 vs. HiLo-Tec 0.345, without rank reversal. Under Reinforcement +30%, HiLo-Tec increases to 0.364 (largest margin). Across all 30 scenarios, no rank change occurred at the top; the only near-crossover occurred with Interlocking ≥ +30%. Only extreme reweighting assigning over 70% of total importance to the interlocking criterion could theoretically reverse the ranking, which is unrealistic in practice. This confirms that the proposed decision model is robust and not sensitive to moderate variations in expert opinions.

4.4. Implications for Design and Practice

The results suggest that the selection of ICEB geometry should be informed by laboratory strength data, as well as considerations regarding constructability compatibility and human factors. Dual circular interlocks and two full-height cores are the key features of the proposed configuration (Figure 8), which allows for the adjustment of both reinforced and unreinforced arrangements to accommodate seismic requirements.

In practical applications, it is advisable to have a core diameter of 50–70 mm, a target weight of 3–5 kg, and rounded edges to enhance grip and reduce hand fatigue. The double-wythe arrangement, with a wall thickness of approximately 254 mm, complies with the standard masonry wall specifications commonly adopted in conventional construction practices. This enables the direct replacement of burnt-brick masonry without the necessity of retraining or equipment modifications. The results have implications that extend beyond ICEB design. The AHP framework serves as a transparent decision-making tool for various material-geometry trade-offs, including the most suitable configuration of prefabricated blocks, modular brick sizing, and green mortar composition, in contexts where expertise is substantial but quantitative data are insufficient.

4.5. Experimental Performance Evaluation of Selected Geometry

An extensive cyclic experiment was carried out on a domestically built ICEB wall to verify the analytical findings of the AHP framework [29]. The decision-making process yielded the most advantageous configuration, which consisted of a wall made of double-wythe interlocking units with continuous vertical cavities for grout and reinforcement. Appropriate grout fluidity and head are critical to ensure full cavity filling and bond development [30,31]. The grout used in this study is a 1:2:4 mix with a maximum aggregate size of ≤12.7 mm and a slump of 150 ± 20 mm, which provides adequate flow through Ø 58.7 mm cores without segregation. According to TMS 402/602-16 [32] and ASTM C476 [33] guidelines, the minimum clear cover between grout and bar should exceed 12.7 mm; the adopted geometry provides ≈23 mm clearance on each side, ensuring unobstructed grout placement at a low gravity-fed head (≈0.6 m). No mechanical pumping was required, confirming compatibility between hole size, grout rheology, and gravity flow conditions.

Under quasi-static displacement-controlled lateral loading, the ICEB wall exhibited a lower initial stiffness of 7.2 kN/mm and a peak lateral strength of 40 kN with significantly higher drift capacity of 2% compared to 0.08% for the traditional solid mortar-bonded wall. Distributed cracking and stable post-peak resistance confirmed the beneficial influence of vertical reinforcement and grout confinement, which had been assigned the highest importance in the AHP results.

In the broader research context, the behavior of the developed ICEB system can be related to findings from the HiLo-Tec program [33,34], which characterized dry-stack interlocking masonry constructed without grout or reinforcement. The superior cyclic behavior of the HiLo-Tec configuration can be explained by its geometry. The dual full-height cores enable uniform grout confinement of the inserted Ø 12.7 mm rebars, promoting composite action and delaying bar buckling under cyclic loading. The moderate unit height (90 mm) and two-key interlock provide inter-course shear transfer without inducing stress concentrations at the web–face junctions. The relatively light weight (5–7 kg) limits inertial demand and facilitates better alignment, which helps distribute shear cracks evenly. These geometric features collectively improve ductility and residual strength, consistent with the field test observations and previous findings on grouted interlocking masonry [7,14]. The HiLo-Tec studies demonstrated that mechanical interlocking alone could provide stability and ease of assembly for low-cost housing in moderate seismic regions. The configuration, while conceptually similar to HiLo-Tec in interlocking principles, differs in purpose and detailing; it employs grouted vertical cores, reinforcing bars, and a double-wythe arrangement to meet the seismic performance requirements of high-hazard zones. Because the test conditions, material properties, and construction details are distinct, direct quantitative comparison is not attempted. Instead, the two systems are regarded as complementary: the HiLo-Tec research establishes the feasibility of dry-stack interlocking masonry, whereas the grouted and reinforced ICEB wall validated the concept toward higher seismic resilience and constructability. This alignment between the decision-based prioritization and the experimentally observed performance confirms the technical soundness and contextual relevance of the proposed ICEB configuration for sustainable masonry construction in developing regions.

5. Conclusions

This research validates a decision-making framework for the most suitable configuration selection of interlocking compressed earth brick (ICEB) geometries to achieve construction goals that prioritize structural performance, ergonomic efficiency, and sustainability. Geometric Size, weight, interlocking configuration, reinforcing compatibility, and ergonomics were evaluated transparently and replicated using the stakeholder-weighted Analytic Hierarchy Process (AHP), capturing field and technical views. Key findings from this study are below.

• A manageable weight and grout/reinforcement were the main factors that determined whether the ICEB system was suitable for seismic and labor-intensive sites. The balance between constructability and structural adaptability was achieved primarily through the arrangement of lightweight, double-cavity interconnecting units. The sensitivity analysis, which supported the expert consensus, verified that this ranking remained stable under large modifications.
• Analytical results were verified through full-scale cyclic testing. The initial rigidity of the grouted double-wythe ICEB wall was lower than that of mortar-bonded brickwork, but it exhibited more robust ductility, energy dissipation, and residual strength. The analytical discovery that earthen masonry seismic resistance is contingent upon groutability and reinforcing has been verified by this performance data.
• The outcomes of the decision-making process and experimental observations suggest that ICEB systems, when effectively designed for local production and enhanced construction, can function as a technically and environmentally feasible alternative to fired-brick masonry in seismic areas. With the help of the suggested AHP framework, designers, practitioners, and policymakers can systematically incorporate expert judgment into the early stages of design to identify the best possible geometries before undertaking significant experimentation.

This study presents a decision framework for selecting interlocking masonry systems in specific locations, incorporating stakeholder perspectives and validating their structural performance. Future research should expand upon this framework by including hybrid decision-making models and developing prototypes that comply with sustainability and seismic standards pertinent to various locales.