Website Cocoon
Green steel, clean cement - Low-carbon construction materials for the builders of tomorrow
About Cocoon
At Cocoon, we’re developing low-carbon construction materials for the builders of tomorrow. Steel and cement account for nearly 15% of global CO₂ emissions, and decarbonising these industries requires completely new approaches to mix design, testing, and implementation.
We’re now building our in-house concrete capability so we can qualify SCMs, validate performance against industry standards, and support deployment of our technology at pilot and demo-scale. To do this, we’re establishing a fully equipped concrete laboratory in London — and we’re looking for a Concrete Technologist to help make it happen.
Responsibilities:
The Role
We’re looking for a Concrete Technologist to design, mix, test, and manage concrete across an extensive experimental programme. You’ll help establish our concrete lab from the ground up, commission equipment, write SOPs, and deliver mechanical and durability testing to ASTM, BSI, and related standards.
You’ll run the full lifecycle of concrete development — from mix design and batching, through casting and curing, to compressive strength and durability testing — while keeping meticulous data records and maintaining a safe, well-organised laboratory. You’ll also support field trials, coordinate external testing, and contribute technical insights to our research and commercial teams.
This role is hands-on, varied, and central to Cocoon’s ability to qualify SCMs, validate performance, and scale towards real-world deployment.
Responsibilities
Concrete Development & Testing
- Develop concrete mix formulations across the experimental matrix (SCM replacement, admixtures, w/b ratios) to ASTM C1709 and BSI Flex 350.
- Plan batching schedules, specimen numbers, test timelines, and weekly execution plans.
- Optimise mix proportions and troubleshoot workability, flash setting, segregation, and strength issues.
- Operate the mixer and conduct fresh property tests (slump, density, air content, bleeding).
- Record batch data (temperature, timings, slump, w/b) and maintain full QA/traceability.
- Cast cubes and cylinders; manage curing tanks, curing regimes, and specimen conditioning.
- Perform compressive and flexural strength testing at 7, 28, and long-term ages.
- Prepare and run durability tests (RCPT, bulk resistivity, water absorption, sorptivity, permeability, drying shrinkage, sulfate resistance, carbonation depth).
Laboratory Setup, Management & Safety
- Write SOPs for all concrete lab processes and commission existing equipment.
- Identify, procure, and install the missing equipment required for the testing regime.
- Conduct baselining exercises for cement and industry incumbents.
- Maintain calibration, servicing, and safe operation of all equipment.
- Manage consumables (PPE, mould oil, aggregates, cement) and keep the lab organised and compliant.
- Ensure all risk assessments are in place and adhered to.
Data, Collaboration & External Coordination
- Maintain digital logs, record raw data, and align outputs with current data storage methods.
- Process and analyse test results; prepare technical reports and summaries, and present data for internal reviews, meetings, and partner updates.
- Advise on SCM qualification routes and recommend workflow improvements.
- Train team members in SOPs, mixing, fresh testing, and equipment use.
- Coordinate outsourcing for tests not done in-house and manage samples, logistics, and external data integration.
- Support small-scale field trials and demonstration pours, including onsite testing.
You’ll Succeed In This Role If You…
- Have hands-on experience in concrete testing, materials laboratories, or construction materials research.
- Are confident working to ASTM, BS EN, and other standards.
- Enjoy practical, repetitive experimental work and take pride in process discipline.
- Communicate clearly and maintain rigorous documentation.
- Thrive in a fast-moving environment with changing priorities.
- Are proactive, organised, and comfortable owning a lab space.
To apply for this job please visit jobs.recruit.charliehr.com.