Search

It is well known that geopolymer products can be made using materials that are rich in silica and alumina with alkalis as polymerisation agent. The chemical reaction, also known as poly-condensation, takes place with the assistance of thermal and/or mechanical activation. This paper discusses the production of moderate-strength geopolymer cubes using two sources of locally available raw materials, viz. soil and brick powder (BP). Instead of using industrial by-products such as fly ash and ground granulated blast furnace slag an attempt has been made to produce lime–pozzolana cement (LPC) on a very small scale and use it as an activator. The major objective was the production of geopolymer cubes which can eventually be used in masonry applications. Initially, a series of tests were conducted, by varying the proportion of soil and brick powder, to produce cubes with moderate strength (3.5–10.0 MPa). The studies revealed that the strength gain was due to contribution of pozzolanic reaction as well as polymerisation. The strength gain has been further enhanced by thermal activation at ambient temperature and mechanical activation by inter-grinding of LPC, BP and soil. This paper provides the details of production and characterisation of LPC and the strength characteristics of geopolymer–LPC-based cubes.

Strength and quality of load bearing masonry is dictated by the properties of masonry unit, mortar and interaction between them. Currently the construction industry is dominated by cement and cement-based products, but parallelly there have been extensive studies in trying to reduce quantity of cement and promote use of alternative cementitious materials. In this regard a masonry unit and mortar combination has been developed which is lime pozzolana cement (LPC) and geopolymer (GP) based, satisfying the strength and serviceability criteria required for the masonry construction. After the experimental investigations, the computation of embodied energy and cost has been carried out which indicate that the designed LPC-GP masonry to be a promising alternative to the conventional cement-based products. The associated advantages of these bricks have also been highlighted through a case study.

Small-scale production of low-cost cements can be an alternative to the conventional cement in the masonry applications. Lime-based products can potentially replace ordinary Portland cement (OPC) in the production of masonry mortar. Lime–pozzolana cement (LPC) is one such binder which can be produced using low capital-intensive infrastructure. They can be used as alternatives to conventional mortar in low-rise load-bearing masonry applications. A variety of locally available ingredients can be used along with LPC to produce moderate-to-high-strength mortars. This paper provides the details of the mortar mixes which have been produced using predominantly soil and brick powder. An attempt has been made to mobilize the strength gain not only through the hydration of the LPC and pozzolanic materials but also through low-molar alkaline activation. It is well known that alkaline solution can be used with reactive silica and/or alumina, and alkali activation can be achieved even at ambient tropical temperatures. This paper provides the details of how the alkaline solution was optimized. Mortars need to be evaluated for strength and workability. All the strength properties needed for classification of mortar have been evaluated. It is found that the strength development depends on the combination of pozzolanic reaction and geopolymerization. All the mixes achieved adequate strength for application in masonry construction. The masonry properties are comparable to cement mortar, and some values have outperformed.

Soil-based blocks and binders have emerged as sustainable alternative to masonry units, and alkali-activated polymers (geopolymers) are being studied as alternatives to cement. This study attempts to stabilise soil using a combination of geopolymerisation and hydration. Strength gain and applicability of soil-based LPC-industrial by-products-geopolymer mortar is studied. In order to optimise the usage of alkaline materials, a series of parametric studies were carried out. A combination of LPC and fly ash led to wet compressive strength of more than 10.0 MPa while a combination of LPC and ultra-fine slag resulted in strength of nearly 20.0 MPa.