Publication

The effect of pore microstructure on strength and chloride ingress in blended cement based on low kaolin clay

Abstract

The objective of this study is to analyse the mechanical and durability properties of a high-performance mortars based on low grade kaolin clay and the effect of electrical conductivity and pore microstructure on the chloride penetration resistance. A total of six mixes were prepared with binary and ternary binders in which a high volume of cement was replaced by low-grade calcined kaolin clay, fly ash and limestone powder. The percentage of kaolinite in the clay used from the Southeast European region was less than 20%. The variations in compressive strength and chloride transport coefficient were analysed experimentally and related to the pore structure and electrical conductivity. Compressive strength, chloride migration and diffusion coefficients, and bulk conductivity were determined using mortar samples, while the pore size distribution was determined by mercury intrusion porosimetry (MIP) on hardened cement paste after 7,28, and 90 days of curing. To understand the capillary absorption of these mixtures, sorptivity indices were measured after 28 and 90 days. The experimental characteristics of the pore size distribution, such as mean pore entry radius (r(0.5)), permeable porosity (P), capillary porosity (?), and critical pore diameter (r(c)), were calculated using the cumulative data of the intruded volume as a function of pressure obtained by MIP. In addition, the extrusion-intrusion curve was used to calculate the pore entrapment fraction (alpha) and the degree of interconnectivity of the pore structure. The evolution of pore structure parameters was monitored for up to 90 days and their effects on strength and chloride penetration were studied in detail. The results showed that all mixes (even those with low kaolinite content) can be used in high performance cement systems and the pore structure has a limited effect on chloride penetration.

About this result
This page is automatically generated and may contain information that is not correct, complete, up-to-date, or relevant to your search query. The same applies to every other page on this website. Please make sure to verify the information with EPFL's official sources.
Related concepts (36)
Cement
A cement is a binder, a chemical substance used for construction that sets, hardens, and adheres to other materials to bind them together. Cement is seldom used on its own, but rather to bind sand and gravel (aggregate) together. Cement mixed with fine aggregate produces mortar for masonry, or with sand and gravel, produces concrete. Concrete is the most widely used material in existence and is behind only water as the planet's most-consumed resource.
Clay
Clay is a type of fine-grained natural soil material containing clay minerals (hydrous aluminium phyllosilicates, e.g. kaolinite, Al2Si2O5(OH)4). Clays develop plasticity when wet but can be hardened through firing. Most pure clay minerals are white or light-coloured, but natural clays show a variety of colours from impurities, such as a reddish or brownish colour from small amounts of iron oxide. Clay is the oldest known ceramic material. Prehistoric humans discovered the useful properties of clay and used it for making pottery.
Portland cement
Portland cement is the most common type of cement in general use around the world as a basic ingredient of concrete, mortar, stucco, and non-specialty grout. It was developed from other types of hydraulic lime in England in the early 19th century by Joseph Aspdin, and is usually made from limestone. It is a fine powder, produced by heating limestone and clay minerals in a kiln to form clinker, grinding the clinker, and adding 2 to 3 percent of gypsum. Several types of portland cement are available.
Show more
Related publications (75)

Influence of Low- to Medium-Kaolinite Clay on the Durability of Limestone Calcined Clay Cement (LC3) Concrete

Karen Scrivener, Matea Flegar

The kaolinite content is principally responsible for the durability performance of Limestone Calcined Clay Cement (LC3), which calls into question its global applicability. The clay supply has a significant impact on the LC3 system's reduced carbon footpri ...
MDPI2023

Durability Challenges of Low-Grade Calcined Clay Opposed to High-Volume Fly Ash in General Purpose Concrete

Karen Scrivener, Matea Flegar

With the decrease in availability of common supplementary cementitious materials (SCMs) such as fly ash in Europe, the search for appropriate SCMs should be dealt with locally. A com-bination of abundant low-grade calcined clay and limestone powder has pro ...
AMER SOC TESTING MATERIALS2023

Characterisation and hydration kinetics of beta-C2S synthesised with K2SO4 as dopant

Karen Scrivener, Franco Alberto Zunino Sommariva, Shashank Bishnoi, Sreejith Krishnan

In this study, a protocol for synthesising beta-C2S using K2SO4 as a dopant has been reported. Quantitative X-Ray diffraction was used to characterise synthesised samples. It was observed that it is possible to synthesise beta-C2S with high purity (>96 wt% ...
PERGAMON-ELSEVIER SCIENCE LTD2023
Show more
Related MOOCs (2)
Cement Chemistry and Sustainable Cementitious Materials
Learn the basics of cement chemistry and laboratory best practices for assessment of its key properties.
Sorption and transport in cementitious materials
Learn how to study and improve the durability of cementitious materials.

Graph Chatbot

Chat with Graph Search

Ask any question about EPFL courses, lectures, exercises, research, news, etc. or try the example questions below.

DISCLAIMER: The Graph Chatbot is not programmed to provide explicit or categorical answers to your questions. Rather, it transforms your questions into API requests that are distributed across the various IT services officially administered by EPFL. Its purpose is solely to collect and recommend relevant references to content that you can explore to help you answer your questions.