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Trial Start Date
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Before
May 01, 2024
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August 02, 2025
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Last Published
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May 20, 2026 01:09 PM
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October 04, 2026 05:00 AM
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Intervention (Public)
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Before
The study evaluates the transition from traditional fired clay bricks to cleaner concrete/soil blocks in the construction sector through a clustered randomized controlled trial with three arms:
Control Group: Participants in these Upazilas receive no intervention and continue with business-as-usual operations.
Treatment 1 (Information & Facilitation): Contractors and relevant stakeholders receive an information and facilitation package delivered through in-person workshops. This includes a concise booklet summarizing the policy context (government shift towards blocks), comparative benefits and costs, a directory of local block supplier contacts, and basic workmanship guidance.
Treatment 2 (Information & Facilitation, Worker's training): Along with the Treatment 1 package, randomly selected one worker from each contractor in Treatment 2 will get hands on training on the use of blocks.
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After
The study evaluates the transition from traditional fired clay bricks to cleaner concrete/soil blocks in the construction sector through a clustered randomized controlled trial with three arms:
Control Group: Participants in these Upazilas receive no intervention and continue with business-as-usual operations.
Treatment 1 (Information & Facilitation): Contractors and relevant stakeholders receive an information and facilitation package delivered through in-person workshops. This includes a concise booklet summarizing the policy context (government shift towards blocks), comparative benefits and costs, a directory of local block supplier contacts, and basic workmanship guidance.
Treatment 2 (Information & Facilitation, Worker's training): Along with the Treatment 1 package, one randomly selected worker from each contractor is invited to the workshop and to a hands-on training session on the use of blocks.
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Intervention End Date
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January 22, 2026
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After
February 22, 2026
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Primary Outcomes (End Points)
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Before
Primary endpoints capture adoption and awareness of eco-friendly blocks, measured separately for each actor type.
Confirmatory primary outcomes:
For contractors (N=792): (1) Ever used eco-blocks - binary indicator for having ever used hollow concrete blocks (HCB) or compressed/stabilized soil blocks (SSB) instead of fired clay bricks (baseline mean = 27.1%, MDE = 11.4 pp or 0.26 SD), and (2) Awareness index - continuous index (0-2) summing policy awareness and information receipt (baseline mean = 0.81, MDE = 0.17 units or 0.26 SD).
For construction workers (N=1,584): Ever worked with eco-blocks - binary indicator for having ever worked on a project using HCB/SSB (baseline mean = 31.9%, MDE = 9.0 pp or 0.19 SD).
For private clients (N=528): (1) Awareness index - identical construction to contractors (baseline mean = 0.534, MDE = 0.20 units or 0.30 SD); and (2) Used blocks in construction - binary indicator for having ever used eco-blocks in own construction (baseline mean = 3.0%, MDE = 5.3 pp or 0.31 SD). Both are confirmatory primary outcomes. The MDE for client block adoption in SD units (0.31 SD) is statistically equivalent to the awareness index (0.30 SD); the low baseline (3%) is reflected in the power calculation via a conservative rho=0.20 assignment and does not justify downgrading the classification. The preferred estimand restricts to baseline non-adopters (N approx. 512, 97% of clients), where "ever used" at endline equals new adoption since baseline, eliminating the floor-effect concern by construction. Adoption is the terminal behavioral outcome of the theory of change; classifying the mechanism (awareness) as primary while treating the terminal outcome as exploratory would invert the causal logic.
Exploratory outcomes (limited power):
Evaluated tender with blocks (procurement officers, N=152) - binary indicator for having evaluated a government tender that included eco-blocks (baseline mean = 49.3%, MDE = 0.59 SD). Classified as exploratory due to small sample (approximately 2 officers per cluster). Procurement officers attend workshops primarily as a belief signal; any direct behavior change is a positive externality.
Compliance/manipulation check (not a confirmatory outcome):
Received training on blocks (T2 workers, N=528) - binary indicator for having received training on working with eco-blocks (baseline mean = 2.3%, MDE = 3.8 pp or 0.26 SD, using contractor-level clustering with 264 contractors and 2 workers each). Reported prominently but not a confirmatory primary outcome, as it measures intervention delivery rather than substantive adoption behavior.
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After
The study has three confirmatory primary outcomes, all measures of block adoption. Each is tested once, at the contrast that matches the group receiving the intervention.
Contractors (N=792), T1 and T2 combined versus Control: (1) ever used eco-blocks (hollow concrete or compressed stabilized soil blocks instead of fired clay bricks).
Construction workers (N=1,584), T2 versus Control: (2) ever worked with eco-blocks.
Private clients (N=528), T1 and T2 combined versus Control: (3) used eco-blocks in their own construction.
A primary outcome is a confirmatory finding when its sharpened false-discovery-rate q-value and its randomization-inference p-value are both below 0.05 within the family of the three outcomes.
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Primary Outcomes (Explanation)
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Before
Block adoption outcomes (ever used eco-blocks, ever worked with eco-blocks, used blocks in construction) are binary indicators equal to 1 if the respondent reports ever using hollow concrete blocks or compressed/stabilized soil blocks instead of fired clay bricks, and 0 otherwise.
The Awareness index is the sum of two binary items: (1) aware of government policy preferring alternatives to fired clay bricks in public procurement, and (2) received information about eco-friendly blocks in the past year. Range: 0-2. One component ("received information") is close to a manipulation check, so a featured sensitivity analysis reports the government policy awareness component alone alongside the composite index in the main results tables. If treatment moves the composite but not the policy awareness component, this suggests the effect is driven by treatment exposure recall rather than substantive information gain.
Evaluated tender with blocks (procurement officers) is a binary indicator equal to 1 if the officer has evaluated a government tender that included HCB/SSB, and 0 otherwise.
Received training on blocks (workers, T2 compliance check) is a binary indicator equal to 1 if the worker has received any training on working with eco-blocks, and 0 otherwise.
For the adoption outcomes, we pre-specify a tiered adoption analysis: (1) Confirmatory: full-sample ANCOVA of “ever used"—conditions on baseline adoption status; the MDEs in Section 5 are computed for this estimand. (2) Featured supplementary: baseline non-adopter conversion—restricts to respondents who had not adopted at baseline; for these respondents, "ever used” at endline equals “new adoption since baseline,” providing a clean conversion estimand featured alongside the main results. (3) Supporting robustness: endline-only “new adoption since baseline"—the direct flow measure cannot benefit from ANCOVA adjustment; reported as a robustness check.
For private clients, the repeated "ever used” item retains identical wording across waves for ANCOVA comparability; “new adoption since baseline” is measured separately as an endline-only complementary outcome.
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After
Adoption (outcomes 1 to 3) is a binary indicator of ever having used eco-blocks; for workers, of ever having worked on a project that used them. A baseline adopter should still report adoption at endline, so the endline outcome is coded history-consistently: the maximum of the baseline value and the endline answer given after a verification prompt to any baseline adopter who reports non-adoption. For workers, a yes given only for a training session is coded 0, because the outcome is work on a construction project. A respondent who is not re-interviewed counts as attrited. The raw endline answer is a robustness check, and the rate of baseline-yes, endline-no answers is reported by arm. Baseline means are 27.1% (contractors), 31.9% (workers) and 3.0% (clients).
Adoption is analyzed three ways. The full-sample ANCOVA of the history-consistent outcome is the confirmatory test. The same model among baseline non-adopters (about 577 contractors and 512 clients) is a featured supplementary analysis of new conversion, reported beside it. An endline-only indicator of first use since baseline is an exploratory outcome. The confirmatory finding rests on the full-sample estimate.
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Power calculation: Minimum Detectable Effect Size for Main Outcomes
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Before
With 22 clusters (upazilas) per arm, MDEs assume 80% power, α = 0.05 (two-sided), ANCOVA adjustment (baseline endline correlation ρ = 0.10–0.50 assigned per outcome based on baseline prevalence), and 5–10% attrition. The design has df = 66 – 22 – 2 = 42 (clusters minus strata minus treatment arms). ICCs for primary outcomes are low (ρ_ICC = 0.010–0.018 for contractors, 0.012 for workers), yielding design effects of 1.1–1.5.
Confirmatory primary outcome MDEs: Contractor block adoption (ever used eco-blocks; baseline = 27.1%): MDE = 11.4 pp (0.26 SD) at 5% attrition, 11.7 pp at 10% attrition — detects a 42% relative increase. Contractor awareness index: MDE = 0.17 index units (0.26 SD). Worker block usage (ever worked with eco-blocks; baseline = 31.9%): MDE = 9.0 pp (0.19 SD) — best powered primary outcome. Private-client awareness index: MDE = 0.20 index units (0.30 SD). Private-client block adoption (used blocks in construction; baseline = 3.0%, confirmatory full-sample N=528): MDE = 5.3 pp (0.31 SD) — statistically equivalent to client awareness index. Non-adopter subsample (N≈512) is a featured supplementary analysis; see Section 4 for the tiered adoption rationale.
Procurement tender evaluation (exploratory; N=152): MDE = 29.3 pp (0.59 SD). Proposed blocks in tender (exploratory; contractors, N=182): MDE = 16.4 pp (0.48 SD). Both classified as exploratory due to limited power from small conditional samples.
Worker training receipt (compliance check; within-contractor clustering, 264 contractors): MDE = 3.8 pp (0.26 SD).
Estimation strategy: The primary estimand is ITT. The pre-specified confirmatory contrasts are: (1) T1 vs. Control (β₁ — information intervention effect) and (2) T2 vs. Control (β₂ — combined information + training effect). These two contrasts carry confirmatory status. The T2 vs. T1 contrast (β₂ – β₁ — marginal training effect beyond information) is pre-specified and reported for all primary outcomes but is treated as secondary because it tests the incremental value of training beyond information—a more demanding and less-powered comparison.
Binary outcomes are estimated using a linear probability model (LPM). Count outcomes (number of block projects) are estimated using Poisson QMLE; negative binomial regression is reported as a robustness check only.
Multiple comparisons: Confirmatory inference is restricted to five pre-specified primary outcomes tested at two arm-vs-control contrasts (T1 vs. Control; T2 vs. Control), yielding ten confirmatory tests. With α = 0.05 and ten tests, the unadjusted family-wise error rate could exceed 30%, so we pre-specify formal multiple-testing adjustment using Anderson (2008) sharpened false-discovery-rate q-values, computed per contrast family (Family A: 5 primaries × T1 vs. Control; Family B: 5 primaries × T2 vs. Control); see List, Shaikh, and Xu (2019) for the implementation. Sharpened q-values are reported alongside unadjusted p-values in main results tables; q < 0.05 is the pre-specified threshold for confirmatory significance. Pooling all ten tests into a single family is reported as supplementary robustness sharpening. The confirmatory primary outcomes by respondent type are: contractors (2): block adoption (full-sample ANCOVA) and awareness index; workers (1): ever worked with eco blocks; private clients (2): awareness index and used blocks in construction (confirmatory full-sample ANCOVA, N=528; non-adopter subsample N≈512 is featured supplementary). Worker training receipt is a compliance check, not a confirmatory outcome (excluded from the 10-test family).
Procurement outcomes are exploratory due to small sample size (~2 per upazila); proposed-in-tender is exploratory due to conditional sample (N=182). Secondary outcomes are not subject to FDR adjustment and are confirmatory at lower priority; exploratory outcomes are not subject to FDR adjustment and are interpreted as hypothesis-generating. Heterogeneity analyses are exploratory and excluded from the ten-test family.
Inference robustness (reported in main tables): Randomization inference (Fisher exact p-values, 10,000 permutations within district strata) and wild cluster bootstrap p-values (Cameron, Gelbach, and Miller 2008) are reported in the main results tables for all primary outcomes, given the modest number of clusters (22 per arm). Additional robustness checks: results with and without baseline covariates; pooled T1+T2 vs. Control; SDS covariate sensitivity.
Cross-outcome decision rule and adoption interpretation: Confirmatory evidence of intervention effectiveness requires a statistically significant effect (p < 0.05, two-sided) in the hypothesized direction for at least one primary outcome in each of at least two distinct respondent domains (contractors, construction workers, private clients), and at least one qualifying domain result must be a behavioral or adoption outcome (not awareness-only). An awareness-domain result qualifies only if the government-policy sub-item is also significant at p < 0.10; a composite awareness result driven solely by the information-receipt sub-item does not count as a qualifying domain result. If the confirmatory full-sample ANCOVA yields a significant treatment effect but the featured supplementary non-adopter ANCOVA yields a null, the confirmatory determination rests on the full-sample result. If the full-sample ANCOVA is null but the non-adopter ANCOVA is significant, the full sample null is the confirmatory finding; the non-adopter result is reported prominently as corroborating evidence of new-conversion effects but does not overturn the confirmatory null.
We collected the 13-item Marlowe-Crowne short-form Social Desirability Scale (SDS) at baseline to capture individual differences in socially desirable responding.
The total SDS score (0–13) is the sum of binary-coded socially desirable responses. We construct two subscales: an Attribution subscale (0–5, claims of positive traits) and a Denial subscale (0–8, denial of negative traits). The Denial subscale has better reliability (α = 0.59) than the full scale (α = 0.48) or the Attribution subscale (α = 0.28).
The mean total SDS score is 8.79 (SD = 1.81). Procurement officers show the highest social desirability (mean = 9.57), followed by contractors (9.03), private clients (8.83), and workers (8.59).
SDS shows very weak correlations with primary behavioral outcomes (all |r| < 0.05), suggesting self-reported block adoption is relatively unaffected by social desirability bias. Given this weak reliability and near-zero outcome correlations, SDS is excluded from the primary covariate set and addressed as a single robustness exercise: re-estimate primary specifications adding the standardized SDS total score (or the Denial subscale) as a covariate; if treatment effects are substantively unchanged, results are considered robust to response bias. We do not pre-specify SDS heterogeneity analyses (e.g., by SDS tertile) because the scale’s weak reliability and near-zero outcome correlations make such tests uninformative and increase fishing risk.
53 respondents (1.7%) were flagged for data quality review: 32 with perfect SDS scores (13/13), 8 with very low scores (≤3), and 13 with incomplete scales. These are retained in main analyses but examined in sensitivity checks.
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After
Power calculations use the cluster design: 66 upazilas (22 per arm) in 22 district strata, alpha 0.05 (two-sided), 80% power and 5% attrition. Each outcome is adjusted for its baseline value with an assumed baseline-endline correlation (rho) of 0.10 to 0.40 set by outcome type; these are planning assumptions. Intracluster correlations (ICC) come from a random-intercept model for the upazila with district fixed effects, estimated by restricted maximum likelihood: 0.051 for contractor adoption and zero for client adoption. Worker outcomes add a contractor level (ICC 0.0265 for the upazila and 0.229 for the contractor). The design effect allows for unequal cluster sizes; the primary design effects are 1.00 to 1.78. Degrees of freedom are 42 for an arm against Control and 43 for T1 and T2 combined against Control.
Minimum detectable effects (MDE) of the primary outcomes at their confirmatory contrasts:
Contractors, ever used eco-blocks: 11.7 percentage points (0.26 SD) from a baseline of 27.1%.
Workers, ever worked with eco-blocks (T2 versus Control): 10.8 percentage points (0.23 SD) from a baseline of 31.9%.
Private clients, used eco-blocks: 4.6 percentage points (0.27 SD) from a baseline of 3.0%, or 5.7 points if the treated-arm variance is taken at the treated rate.
At 10% attrition the contractor adoption MDE is 11.9 points and the worker MDE 10.9 points. If only one primary outcome has an effect, its sharpened q-value is below 0.05 only if p is at most 0.016, and the primary MDEs are then 0.27 to 0.31 SD. At the estimated upazila ICC and at twice and three times it (floors of 0.01 and 0.02 for client adoption), the primary MDEs at their confirmatory contrasts lie between 0.23 and 0.34 SD.
Other MDEs: secondary outcomes 0.24 to 0.41 SD at the arm-versus-Control contrast; knowledge test (endline only) 0.26 SD (contractors) and 0.30 SD (clients) at the combined contrast; worker skill test (endline only, T2 versus Control) 0.24 SD, using the design effect of worker block usage; procurement officers (N=152) 0.48 SD for organized contractor training and 0.55 SD for evaluated tender; baseline non-adopters 0.31 SD (contractors, N=577) and 0.28 SD (clients, about 512); selected against unselected T2 worker 0.21 SD (238 intact pairs after attrition); unselected T2 workers against Control or T1 workers 0.26 SD; worker training receipt 3.7 points (0.25 SD); officer quality training 22.2 points (0.54 SD).
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Field
Intervention (Hidden)
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Before
The intervention is organized at the district level and implemented in clusters at the Upazila (sub-district) level. The study surveys contractors, procurement officers, construction workers, and private clients at baseline and endline, with outcomes defined at the respondent level. Intervention includes in-person workshops, as well as follow-up visits for those who missed the workshops, to provide them with treatment exposure and materials. This will take place from November 2025 to January 2026.
Contractors, Private Client and Procurement Officers: In treated Upazilas (T1 and T2), private and public contractors, private client, and procurement officers receive the information package trough in person workshop to test if removing information frictions at the regulatory/approval level influences contractor, and client material choice. As procurement officers mostly deals with the government related projects, bringing different stakeholders in one workshop could also works as a trust factor in increasing the adoption of alternative materials to fired clay bricks.
Worker Spillovers (Within-Cluster T2): In Treatment 2, the skills training is not given to all workers. Instead, one worker per contractor is randomly selected for training. This design feature allows for the measurement of peer effects and knowledge spillovers to untreated co-workers within the same firm, distinguishing between direct training effects and indirect learning.
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After
The intervention was organized at the district level. The workshops were held in each treated upazila from 3 November 2025 to 22 January 2026, and follow-up visits delivered the materials to invitees who had missed them until 22 February 2026.
T1 and T2 upazilas: contractors, procurement officers and private clients were invited to one in-person workshop that brought the three groups together. It covered the government policy on blocks, the costs and benefits of blocks compared with fired clay bricks, and technical specifications; block-laying technique was shown on slides and in discussion, without hands-on practice. Participants received a booklet on the advantages of blocks, the regulatory requirements and workmanship, and a directory of block producers. Invitees who missed the workshop received the printed materials in a follow-up visit. Participation was voluntary: invitees were contacted before the workshops, and those who came signed the attendance sheet as their consent. Procurement officers took part mainly so that contractors and clients would see that the policy has institutional backing. Construction workers were not invited in T1.
T2 upazilas only: one of each contractor's two surveyed workers, selected at random, was also invited to the workshop and to a 30-minute hands-on training session on block handling, the proportioning of materials, block laying and quality assessment. The other surveyed worker was not invited.
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Field
Secondary Outcomes (End Points)
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Before
Secondary outcomes capture mechanisms consistent with the information and coordination channels in the theory of change.
For contractors (N=792): (1) Received info on eco-blocks—whether the respondent received information about eco friendly blocks in the past year (baseline = 16.3%, MDE = 0.29 SD), measuring direct information exposure through the T1 channel; (2) Aware of government policy—whether the respondent knows government prefers alternatives to fired clay bricks (baseline = 64.4%, MDE = 0.25 SD); (3) Ease of contacting suppliers—measured on a 5-point ordinal scale (Very Difficult to Very Easy); the main analysis uses a binary recode (Moderate Easy/Very Easy = 1; variable: easy_supplier_contact; baseline = 52.5%, MDE = 0.28 SD), with the full ordinal variable treated as continuous in OLS reported as a robustness check; (4) Advised clients to use blocks—whether the contractor has recommended eco-blocks to private clients (baseline = 38.9%, MDE = 0.24 SD); (5) Knows local block supplier—whether the contractor knows a local eco-block supplier, directly targeted by the supplier directory covering 122 verified producers (baseline = 28.7%, MDE = 14.2 pp or 0.31 SD in the contractor-only main specification; a supplementary pooled contractor+client specification yields MDE = 10.6 pp or 0.26 SD).
For construction workers (N=1,562): Peer uses blocks—whether the worker is aware of peer workers who have worked with eco-blocks (baseline = 26.7%, MDE = 0.25 SD).
For private clients (N=528): (1) Knows local block supplier—whether the client knows a local eco-block supplier (baseline = 11.2%, MDE = 0.35 SD); (2) Aware of government policy (baseline = 40.9%, MDE = 0.30 SD).
For the secondary outcome “knows block supplier,” the pre-specified main analysis estimates separate effects by respondent type (contractors, private clients). A supplementary pooled interacted model combining contractors and private clients (N=1,320) tests whether effects differ across respondent types. The pooled regression includes respondent-type fixed effects and treatment-by-type interactions; both the pooled model and the separate-sample estimates are reported regardless of interaction significance.
The following outcomes are pre-registered as exploratory due to limited statistical power, small sample sizes, or indirect intervention alignment.
For contractors (government tender participants only, N=182): Proposed blocks in tender - whether the contractor has ever proposed eco-blocks in a government tender (baseline = 13.2%, MDE = 0.48 SD), reclassified from secondary to exploratory because the conditional sample (N=182, approximately 23% of contractors) yields an MDE substantially larger than the primary contractor outcomes (both 0.26 SD) and larger than the client adoption outcome classified as primary (0.31 SD). The study is underpowered for confirmatory inference on this outcome.
For contractors (N=792): Block market access - a continuous index (0-1) measuring supplier accessibility, constructed as the average of perceived block availability and knowing a local supplier (baseline = 25.3%, MDE = 0.37 SD), classified as exploratory as a mechanism variable for the coordination channel.
Barrier perceptions index (contractors) - a z-scored index from 4 binary barrier items with meaningful baseline variation: blocks not easily available (60.5%), not preferred by clients (24.6%), not mentioned in tender (20.6%), and lack of awareness (14.4%). Six additional barrier items excluded due to floor effects (less than 7% prevalence). Captures information and coordination frictions targeted by T1 (N=577 non-adopter contractors, MDE = 0.29 SD).
For procurement officers (N=152): Environment in top 3 bid criteria - whether the officer ranks environmental considerations among top 3 tender evaluation criteria (baseline = 2.6%, MDE = 0.58 SD), classified as exploratory due to small sample and floor effect. Received quality training - whether the officer has received training on assessing eco-block quality in tenders (baseline = 21.1%, MDE = 0.57 SD), reclassified from secondary to exploratory; all procurement officer outcomes are exploratory due to approximately 2 officers per upazila cluster, with MDEs ranging from 0.56 to 0.59 SD across the four PO outcomes.
For private clients (N=528): Received info on eco-blocks - whether the client received information about eco-friendly blocks in the past year (baseline = 12.5%, MDE = 0.30 SD), classified as exploratory because it is a supportive mechanism/manipulation measure rather than a focal confirmatory endpoint.
Endline-only measures: The following are collected only at endline because they capture post-intervention states. ANCOVA adjustment is not available for these outcomes.
Compliance and dosage: (1) Workshop attendance (all treated respondents)—binary indicator equal to 1 if the respondent attended the BRAC/BIGD information workshop. (2) Training dosage (T2 contractors only)—number of workers per contractor who actually received hands-on training (0, 1, or 2), required for the pre-specified dose-response analysis. (3) Used supplier directory (T1/T2 contractors and private clients)—binary indicator equal to 1 if the respondent consulted the supplier directory, separating directory compliance from workshop attendance.
Contamination check: SUTVA is threatened when substantive treatment content reaches the control group, not when respondents merely hear that a workshop occurred. We measure: (1) Received workshop materials (all respondents, especially Control)—binary indicator equal to 1 if the respondent received printed eco-block materials (leaflets, supplier directory, cost comparison sheets) from someone outside their upazila, capturing material leakage. (2) Received detailed block information from external source—binary indicator equal to 1 if someone shared specific information about block costs, supplier contacts, or technical specifications, distinguishing substantive treatment leakage from general awareness.
Adoption dynamics: (1) New adoption since baseline (contractors and private clients)—binary indicator equal to 1 if the respondent used eco-blocks for the first time since baseline. For private clients, this outcome is especially important because baseline adoption is rare (3.0%); it complements the repeated “ever used” measure by isolating first-time adoption after the intervention. (2) Number of block projects (contractors)—count of construction projects using eco-blocks in the past 6 months, capturing the intensive margin; analyzed using Poisson QMLE (negative binomial as robustness check).
Mechanism measures: (1) Cost comparison belief (contractors and private clients)—perceived relative cost of blocks versus bricks on a 5-point scale (1 = much cheaper to 5 = much more expensive, with “don’t know” option). (2) Post-use satisfaction (contractors and private clients who used blocks)—overall satisfaction on a 5-point Likert scale.
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After
Secondary outcomes, reported with 95% confidence intervals and unadjusted p-values and not used for confirmatory claims:
Contractors (N=792): awareness index (0-2; baseline 0.81); knows a local block supplier (28.7%); ease of contacting suppliers (52.5%); advised clients to use blocks (38.9%); proposed blocks in a government tender (3.0%).
Construction workers: knows a nearby worker who works using blocks (N=1,562; 26.7%); block-laying skill test (endline only, all arms).
Private clients (N=528): awareness index (0.53); knows a local block supplier (11.2%).
Contractors and private clients, all arms: knowledge test, endline only (contractors 0-4, clients 0-2).
Exploratory outcomes, procurement officers (N=152): evaluated a tender that included eco-blocks (49.3%); organized training for contractors on eco-block use (9.9%).
Exploratory endline-only outcomes: first use of eco-blocks since baseline (contractors, clients); number of block projects and total projects since baseline (contractors); belief about the cost of blocks against bricks, with "don't know" as its own indicator (contractors, clients); suppliers contacted (contractors, clients); people told about blocks (contractors, clients); a government tender requiring or encouraging blocks (contractors, officers); poor-quality blocks seen in use (contractors, workers).
Compliance checks, reported without a tier: received training on blocks (workers; 2.3% among T2 workers at baseline); received training to assess block quality (officers; 21.1%); workshop attendance, from the workshop records with an endline cross-check; hands-on training take-up by the invited worker; use of the supplier directory. Contamination checks: printed block materials or detailed block information received from outside the upazila since baseline.
Reported descriptively only: satisfaction after using blocks, client project timing and walling material, the baseline barrier perception, market access and self-rated knowledge indices, and whether officers rank environmental impact among their top bid criteria.
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Field
Secondary Outcomes (Explanation)
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Before
“Aware of government policy” is a binary indicator equal to 1 if the respondent is aware that government prefers alternatives to fired clay bricks in public procurement, and 0 otherwise.
“Received info on eco-blocks” is a binary indicator equal to 1 if the respondent reports receiving information about eco-friendly blocks in the past year, and 0 otherwise.
“Knows local block supplier” is a binary indicator equal to 1 if the respondent reports knowing a local eco block supplier and 0 otherwise, directly targeted by the supplier directory covering 122 verified producers across 39 districts (~47 upazilas).
“Ease of contacting suppliers” is measured on a 5-point ordinal scale (Very Difficult, Difficult, Moderate, Easy, Very Easy). The main analysis uses a binary recode (= 1 if Moderate, Easy, or Very Easy; 0 if Very Difficult or Difficult; variable: easy_supplier_contact). The full ordinal variable treated as continuous in OLS is reported as a robustness check.
“Advised clients to use blocks” is a binary indicator equal to 1 if the contractor has recommended eco-blocks to private clients, and 0 otherwise.
“Peer uses blocks” (workers) is a binary indicator equal to 1 if the worker is aware of peer workers who have worked with eco-blocks, and 0 otherwise.
The following outcomes are pre-registered as exploratory due to limited statistical power, small sample sizes, or indirect intervention alignment. For contractors (government tender participants only, N=182): Proposed blocks in tender—whether the contractor has ever proposed eco-blocks in a government tender (baseline = 13.2%, MDE = 0.48 SD), classified as exploratory because the conditional sample (N=182, ~23% of contractors) yields an MDE substantially larger than the primary contractor outcomes (0.24–0.26 SD). The study is underpowered for confirmatory inference on this outcome.
For contractors (N=792): Knowledge index—a z-scored composite of correct responses on cost and quality comparisons between eco-blocks and fired clay bricks (z-mean of cost knowledge and quality knowledge items; baseline standardized mean = 0.33 SD, MDE = 0.22 SD), classified as exploratory as an indirect knowledge effect of the T1 information channel.
Block market access—a continuous index (0–1) measuring supplier accessibility, constructed as the average of perceived block availability and knowing a local supplier (baseline = 25.3%, MDE = 0.37 SD), classified as exploratory as a mechanism variable for the coordination channel.
Barrier perceptions index (contractors)—a z-scored index from 4 binary barrier items with meaningful baseline variation: blocks not easily available (60.5%), not preferred by clients (24.6%), not mentioned in tender (20.6%), and lack of awareness (14.4%).
Six additional barrier items excluded due to floor effects (<7% prevalence). Captures information and coordination frictions targeted by T1 (N=577 non-adopter contractors, MDE = 0.29 SD).
For procurement officers (N=152): Environment in top 3 bid criteria—whether the officer ranks environmental considerations among top 3 tender evaluation criteria (baseline = 2.6%, MDE = 0.58 SD), classified as exploratory due to small sample and floor effect.
Received quality training—whether the officer has received training on assessing eco-block quality in tenders (baseline = 21.1%, MDE = 0.57 SD), classified as exploratory.
Organized contractor training—whether the officer has organized training for contractors on eco block use (baseline = 9.9%, MDE = 0.56 SD), classified as exploratory as a multiplier-effect measure.
All four procurement officer outcomes are exploratory due to ~2 officers per upazila cluster, with MDEs ranging from 0.56 to 0.59 SD.
For private clients (N=528): Received info on eco-blocks—whether the client received information about eco friendly blocks in the past year (baseline = 12.5%, MDE = 0.30 SD), classified as exploratory because it is a supportive mechanism/manipulation measure rather than a focal confirmatory endpoint.
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After
The awareness index is the sum of two binary items: awareness that the government calls for concrete or soil blocks instead of fired clay bricks in all public construction, and receipt of any information or experience related to eco-blocks. The information item covers the past 6 months at baseline and the period since the baseline interview at endline, so that it spans the intervention (November 2025 to January 2026). Baseline means are 0.81 (contractors) and 0.53 (clients). Both items are reported beside each index and are not separate outcomes. Workshop attendees report receiving information almost by definition, so a significant index with a non-significant policy item is described as consistent with recall of treatment exposure, not as a gain in policy knowledge. The knowledge test counts correct answers to multiple-choice questions: for contractors four (0-4), on what blocks are made of, how their quality is checked, whether a hollow-block wall costs less than a brick wall, and how much cement and sand it needs; for clients the first and third (0-2). "Don't know" counts as incorrect, and the questions come before the awareness items.
Knows a local block supplier equals 1 if the respondent knows a local eco-block supplier; it is estimated separately for contractors and clients, with no test of a difference between them. Ease of contacting suppliers is asked of all contractors on a 5-point scale; the main measure equals 1 for moderate, easy or very easy, and the 5-point score is a robustness check. Advised clients equals 1 if the contractor has recommended eco-blocks to private clients. Proposed blocks in tender equals 1 if the contractor has ever proposed eco-blocks in a government tender; contractors who report no tender participation are coded 0, because participation could itself respond to treatment. Peer uses blocks equals 1 if the worker knows a nearby worker who works using eco-blocks; "don't know" answers are excluded at endline and their share is reported by arm. The skill test counts correct answers (0-3) on mortar ratio, block orientation and joint thickness; it is asked of all workers, and its headline contrast is T2 versus Control.
Endline-only measures use recall from the baseline interview. Project counts come from a project roster that also records whether each project was public or private and who specified the material. Suppliers contacted is analyzed as any and as two or more; people told as any and as three or more. The cost belief (5-point scale) is estimated on those who answer, beside the "don't know" indicator. The tender item is asked of all contractors, with those who did not bid coded 0.
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