Analyzing the Addition of Calcium Chloride (CaCl2) to the Opus Caementicium Recipe in Order to Improve Setting-Time, Self-Healing Properties, and Compressive Strength

School Name

Spring Valley High School

Grade Level

11th Grade

Presentation Topic

Engineering

Presentation Type

Non-Mentored

Abstract

Concrete is one of the most used building materials on the planet due to its durability, versatility, price, and setting time, with the most common type being OPC. OPC has a lifespan of around 70-100 years in standard applications, however it is significantly lower in maritime environments, about 30-70 years. Harbours are crucial for trade and the economy, and breakwaters are required to protect the coastline from waves. Calcium Chloride (CaCl2) is a modern concrete accelerant which can decrease the setting time of concrete, as well as increase water absorption, creating a more porous concrete. Roman concrete is an ancient building material and has self-healing properties when in contact with seawater or rainwater, but it is slow to set. This works by incorporating lime clasts, causing an exothermic reaction when in contact with water, creating reaction-ready calcium for pore and crack filling. Quicklime or slaked lime was used in “hot mixing” to create an environment with intact high-surface area lime clasts. It was hypothesized that the addition of CaCl2 into the Roman concrete mixture would decrease the setting time, increase compressive strength, and improve the self-healing ability. Concrete samples were created by mixing pozzolanic ash, calcium oxide, aggregate, water, and CaCl2. Samples were tested for setting time using toothpick-depth analysis, compressive strength with a CTM, and self-healing ability with visual inspection. It was found that the addition of CaCl2 into Roman concrete decreased setting time by approximately 34.7%, reduced compressive strength by 31.69%, and nullified the self-healing properties.

Location

Furman Hall 201

Start Date

3-28-2026 11:45 AM

Presentation Format

Oral and Written

Group Project

No

COinS
 
Mar 28th, 11:45 AM

Analyzing the Addition of Calcium Chloride (CaCl2) to the Opus Caementicium Recipe in Order to Improve Setting-Time, Self-Healing Properties, and Compressive Strength

Furman Hall 201

Concrete is one of the most used building materials on the planet due to its durability, versatility, price, and setting time, with the most common type being OPC. OPC has a lifespan of around 70-100 years in standard applications, however it is significantly lower in maritime environments, about 30-70 years. Harbours are crucial for trade and the economy, and breakwaters are required to protect the coastline from waves. Calcium Chloride (CaCl2) is a modern concrete accelerant which can decrease the setting time of concrete, as well as increase water absorption, creating a more porous concrete. Roman concrete is an ancient building material and has self-healing properties when in contact with seawater or rainwater, but it is slow to set. This works by incorporating lime clasts, causing an exothermic reaction when in contact with water, creating reaction-ready calcium for pore and crack filling. Quicklime or slaked lime was used in “hot mixing” to create an environment with intact high-surface area lime clasts. It was hypothesized that the addition of CaCl2 into the Roman concrete mixture would decrease the setting time, increase compressive strength, and improve the self-healing ability. Concrete samples were created by mixing pozzolanic ash, calcium oxide, aggregate, water, and CaCl2. Samples were tested for setting time using toothpick-depth analysis, compressive strength with a CTM, and self-healing ability with visual inspection. It was found that the addition of CaCl2 into Roman concrete decreased setting time by approximately 34.7%, reduced compressive strength by 31.69%, and nullified the self-healing properties.