Concrete Technologist

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 building an in‑house concrete capability to qualify supplementary cementitious materials (SCMs), validate performance against industry standards, and support deployment of our technology at pilot and demo‑scale.

As a Concrete Technologist you will design, mix, test, and manage concrete across an extensive experimental programme. You’ll help establish our laboratory in London, commission equipment, write SOPs, and deliver mechanical and durability testing to ASTM, BSI, and related standards. This role is hands‑on, varied, and central to Cocoon’s ability to qualify SCMs, validate performance, and scale toward 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.

Qualifications

• Hands‑on experience in concrete testing, materials laboratories, or construction materials research.
• 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.
• Proactive, organised, and comfortable owning a lab space.

What We Offer

• A chance to build Cocoon’s concrete lab from the ground up.
• The opportunity to generate data that feeds directly into demo‑plant development.
• Hands‑on experience with a wide range of mechanical and durability tests.
• Collaboration with researchers, commercial teams, and external laboratories.
• Clear growth opportunities as our concrete and materials programmes scale.
• A competitive salary and stock options, plus 28 days of annual leave.

Apply Now – If you’re excited about developing and testing low‑carbon concrete, and helping Cocoon scale toward real‑world deployment, we’d love to hear from you.