Aerated concrete is characterized by the presence of large voids deliberately included in its matrix to reduce the density. This study reports the investigations conducted on the structure of cement-based autoclaved aerated concrete (AAC) and non-AAC with sand or fly ash as the filler. The reasons for changes in compressive strength and drying shrinkage are explained with reference to the changes in the microstructure. Compositional analysis was carried out using XRD. It was observed that fly ash responds poorly to autoclaving. The process of pore refinement in fly ash mixes is discussed with reference to be formation of Hadley grains as well as fly ash hydration. The paste-void interface in aerated concrete investigated in relation to the paste-aggregate interface in normal concrete revealed the existence of an interfacial transition zone.

K. Ramamurthy

Department Of Civil Engineering

Cements

Composition

Compressive strength

Density (specific gravity)

Fillers

Fly ash

Hydration

Interfaces (materials)

microstructure

Scanning electron microscopy

Shrinkage

X ray diffraction analysis

AERATED CONCRETE

AUTOCLAVING

Compositional analysis

DRYING SHRINKAGE

HADLEY GRAINS

PORE REFINEMENT

Concretes

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Microstructural investigations on aerated concrete

Cement and Concrete Research

Though foam concrete was initially envisaged as a void filling and insulation material, there have been renewed interest in its structural characteristics in view of its lighter weight, savings in material and potential for large scale utilization of wastes like fly ash. The focus of this paper is to classify literature on foam concrete in terms of constituent materials (foaming agent, cement and other fillers used), mix proportioning, production methods, fresh and hardened properties of foam concrete. Based on the review, the following research needs have been identified: (i) developing affordable foaming agent and foam generator, (ii) investigation on compatibility between foaming agent and chemical admixtures, use of lightweight coarse aggregate and reinforcement including fibers, (iii) durability studies, and (iv) factors influencing foam concrete production viz., mixing, transporting and pumping. © 2009 Elsevier Ltd. All rights reserved.

Cement and Concrete Composites

A classification of studies on properties of foam concrete

Knowledge of sorption characteristics like absorption and sorptivity of building materials are of importance as they affect the durability and other properties. In the case of lightweight concrete like aerated and foam concrete, the moisture movement behaviour becomes more complex as such concretes contain much larger volume of air voids. This paper is aimed at investigating the sorption-related properties of foam concrete as affected by its composition and pore structure. Water absorption by complete immersion and sorptivity are measured for various mixes with different fly ash replacement levels for sand and different foam volume. It was found that sorption values are lower than the corresponding base mix (without foam) and the values reduce with increase in foam volume. It is also found that sorption depends on the filler type, density and pore structure and also on permeation mechanisms. © 2007 Elsevier Ltd. All rights reserved.

Sorption characteristics of foam concrete

Aerated concrete is relatively homogeneous when compared to normal concrete, as it does not contain coarse aggregate phase, yet shows vast variation in its properties. The properties of aerated concrete depend on its microstructure (void-paste system) and composition, which are influenced by the type of binder used, methods of pore-formation and curing. Although aerated concrete was initially envisaged as a good insulation material, there has been renewed interest in its structural characteristics in view of its lighter weight, savings in material and potential for large scale utilization of wastes like pulverized fuel ash. The focus of this paper is to classify the investigations on the properties of aerated concrete in terms of physical (microstructure, density), chemical, mechanical (compressive and tensile strengths, modulus of elasticity, drying shrinkage) and functional (thermal insulation, moisture transport, durability, fire resistance and acoustic insulation) characteristics.

Structure and properties of aerated concrete: A review

Autoclaved Aerated Concrete

Pore structure of cement silica fume systems Presence of hollow-shell pores11This paper was originally submitted to Advanced Cement Based Materials on 21 August 1997 and accepted on 24 August 1998. The paper was received at the Editorial Office of Cement and Concrete Research on 28 August 1998 and accepted in final form on 14 September 1998.

Microstructural alterations in fly ash mortars: Study on phenomena affecting particle and pore size

Interfacial Transition Zone in Concrete

Journal	Data powered by TypesetCement and Concrete Research
Publisher	Data powered by TypesetElsevier Science Ltd, Exeter
ISSN	00088846
Open Access	No