Geopolymer foam concrete: An emerging material for sustainable construction

Properties and applications of foamed concrete; a review

The thermal conductivity (k-value) of cement-based materials like concrete is an important factor when considering the amount of heat transfer through conduction. The amount of heat loss through walls and roofs has a direct effect on the energy consumption of buildings. The steady state and transient methods are considered the two main thermal conductivity measurement approaches. The moisture content, temperature, type of aggregate, type of cementitious material and density of concrete are influential factors on the thermal conductivity. The aim of this paper is to review the techniques most commonly used to measure the thermal conductivity of concrete as well as to consider the factors affecting the thermal conductivity of cement-based materials. In addition, a general equation for predicting the thermal conductivity of concrete is proposed in this study based on data reported by researchers. The results of this review indicate that most researchers have measured the k-value of cement-based materials based on transient methods. The reported k-value in saturated conditions is higher than in dry conditions. Moreover, the measured k-value exhibits a declining trend with increasing temperature. It is concluded that using lightweight concrete in structural and non-structural building envelopes is a valuable method of reducing the amount of heat transfer and energy consumption owing to the lower k-value of lightweight concrete compared to normal weight concrete.

Thermal conductivity of concrete – A review

Evaluation of thermal conductivity, mechanical and transport properties of lightweight aggregate foamed geopolymer concrete

Effects of expanded polystyrene (EPS) particles on fire resistance, thermal conductivity and compressive strength of foamed concrete

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.

A classification of studies on properties of foam concrete

This paper reports the effects of variation in density, concentration and type of cation associated with sulphate on the expansion, mass and strength loss of foam concrete produced with two synthetic surfactants. Comparisons are made between behaviour of foam concrete of different densities and that of corresponding base mixes of mortar without foam. The investigations indicated that the expansion in sodium sulphate environment was up to 28% higher than that of magnesium sulphate environment which can be attributed to greater quantum of ettringite formation in sodium sulphate environment. The major deterioration mechanism in magnesium sulphate environment is disintegration of cementing material and this contributed to loss in mass of 1% and higher sulphate deterioration factor of 0.4 for specimens under very severe magnesium sulphate environment. Irrespective of the type of sulphate environment, the deterioration of foam concrete was lower than that of base mix.

Behaviour of foam concrete under sulphate environments

This study presents a detailed experimental investigation on the effects incorporating non-metallic fibers in hybrid form in self-compacting concrete (SCC). In this regard SCC was prepared with Alccofine and Metakaolin as partial replacement for cement in 15% and 20% respectively along with the hybrid fibre combinations namely abaca fibres (0.25%, 0.5% & 0.75%), polypropylene fibres (0.5%, 1%, 1.5% & 2%) and glass fibres (0.5%, 1%, 1.5%, & 2%). The fresh properties of SCC with and without hybrid fibre combinations were assessed through the standard tests such as slump flow, J ring and V-funnel tests. The conventional mechanical tests such as compressive strength test, split tensile strength test and flexural strength test were performed at 7 and 28 days. The experimental results reveal that the fresh properties of SCC were highly influenced by alccofine and Metakaolin adopted in this research. Furthermore, that the hybrid combination of abaca with polypropylene and glass fibres improved the mechanical properties of SCC and in particular the mix with 1% glass fibre and 0.25% Abaca fibre had shown better flexural and tensile strength behaviour. Microstructure analyses were also done to confirm the improvement in mechanical properties. The Scanning Electron Microscope images of the mix with 1% glass fibre and 0.25% abaca fibre showed less voids presence and presence of more hydrated components conveying that the usage of hybrid fibres had restricted the propagation of cracks there by reducing the percentage of voids and the use of metakaolin and alcofine helping in forming hydrated components at earlier stage leading to better strength.

https://iopscience.iop.org/article/10.1088/2053-1591/aca5ed/pdf

G. Indu Siva Ranjani

Papers

A classification of studies on properties of foam concrete

Behaviour of foam concrete under sulphate environments

A comprehensive study on physico-mechanical properties of non-metallic fibre reinforced SCC blended with metakaolin and alcofine