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This paper assesses the possibility of utilisation of clay–waste tyre rubber mixes as construction materials for geotechnical structures. Rubber granulates (Rg) and rubber fibres (Rf) were blended with 2.5, 5, 7.5 and 10% clay content. The various combinations of clay–rubber granulates (CRg) and clay–rubber fibres (CRf) were subjected to the sequence of compaction, strength, consolidation and swelling pressure tests. A linear decrementing trend of compaction parameters was observed with an increase in Rg and Rf contents. An insignificant rise in unconfined compressive strength (UCS) and splitting tensile strength (STS) of clay was observed with the addition of Rg and Rf up to 5 and 2.5%, respectively. Higher inclusions had reduced the UCS and STS of clay. However, a continual increase in failure strain was observed with an increase in Rg and Rf contents. The compression index of CRg and CRf mixtures was found to increase with the increase of Rg and Rf contents. A continuous decrease in the soaked California bearing ratio and swelling pressure (σs) of CRg and CRf mixtures was observed with the increase in Rg and Rf contents. In view of code requirements, the pre-requisite treatment of CRg and CRf mixtures should be carried out before field applications.

The geotechnical behavior of fly ash mixed with lime and alccofine is discussed in this paper. The specimens were prepared and cured using the burlap technique for 7, 14, and 28 days. The results of this study showed that the unconfined compression strength, split tensile strength, California bearing ratio, and flexural strength of a fly ash containing 6% lime and 2% alccofine (referred to as the “reference mix”) improved as the curing time increased. After the durability cycles, the reference mix showed a significant increase in the unconfined compressive strength. For the unconsolidated undrained and consolidated drained triaxial tests, the deviator stress and cohesion increased while the friction angle decreased as the curing time increased. The volumetric strain response of the reference mix shows an initial compression followed by large dilation. In the consolidated drained test, the dilatancy behavior of the reference mix suppressed, as the curing time increased. The improved behavior of the fly ash–lime–alccofine mix could boost the construction of rural roads.

The investigation aims to check the effect of variation of gypsum and water content on the engineering properties of expansive soil by different experiments, namely, mini compaction test, Atterberg limit’s test, and unconfined compressive strength test along with microstructural analysis. The effect of gypsum (0%, 2%, 4%, 6%, 8%, and 10%), water content (ωopt − 3%, ωopt, and ωopt + 3%), and curing period up to 28 days on the strength of bentonite-gypsum mixtures was highlighted. The results of bentonite-gypsum mixtures showed an increment in maximum dry unit weight and decrement in the optimum water content up to 4% inclusion of gypsum. A gradual reduction in the liquid limit and plastic limit of bentonite-gypsum mixtures was observed with the increase in gypsum content and curing period. The unconfined compressive strength of the bentonite-gypsum mixtures increased continuously with the increase in gypsum content, water content, and curing period. The microstructural behavior of bentonite-gypsum mixtures showed evidence of pozzolanic product formation along with densification of the composite. The multiple regression analysis was also carried out to establish the relationship between the strength and maximum dry unit weight, liquidity index, and the additive content as well as curing period.

This paper focuses on the effect two forms of waste rubber tyres of granulate (Rg) and fibre (Rf) categories on the compaction–strength–consolidation–swell–durability behaviour of uncemented/cemented clayey soil. The effect of incorporation of five proportions 0%, 2.5%, 5%, 7.5% and 10% Rg/Rf (by weight of soil) and three proportions 0%, 3% and 6% cement (by weight of soil) was assessed. Reduction in maximum dry unit weight (γmax) and optimum water content (ωopt) of clayey soil and cemented clayey soil was observed with the incorporation of ruuber granulates (Rg) and rubber fibres (Rf). Both unconfined compressive strength (UCS) and split tensile strength (STS) of the clayey soil were primarily controlled by the amount of cement and waste rubber tyres and it was found to be decreased with the enhancement in rubber content. But addition of Rg and Rf was found to improve the ductility and strain hardening behaviour of cemented clayey soil, prosperously under unconfined compression. Inclusion Rg was found to be ineffective to overshadow the brittleness of the cemented clayey soil subjected to tensile loads. The inclusion of higher rubber content had lowered the strength of cemented significantly. Decline in the California bearing ratio (CBR) value, swelling pressure (σs) and increment in the compression index (Cc) and weight loss during wet/dry cycles were observed with the incorporation of Rg and Rf in cemented clayey soil. The results of all performed tests were cross checked and compared with various Indian standards to reach at the optimum dose of Rg and Rf that can be added to cemented clayey soil for its possible applications in back filling, construction of embankment (for rural roads), sub-grade course, sub-base course and slide slope of canal. The form of waste rubber tyre i.e. Rg and Rf had significant effect on the geotechnical characteristics of cemented clayey soil. Overall, Rf had outperformed the Rg, considering all evaluated geotechnical properties. Maximum dose of Rg and Rf to be added in cemented clayey soil should not be more than 5% and 7.5%, respectively.

The utilisation of end-of-life tires nowadays has become a matter of great distress across the globe when left unattended. These tires have been proved to be a malady on the environment causing severe pollution and health hazards. Hence, the potential use of end-of-life tires has been crucial, especially due to the uncontrolled population rise in urban areas which demands construction on undesirable soil. This paper examines the load–deformation behaviour of rubber fibre–reinforced cemented clayey soil through laboratory tests such as unconfined compressive strength (UCS) and split tensile strength (STS) tests. The clayey soil was stabilised with 3 and 6% cement content, and the inclusion level of rubber fibres was kept at 0, 2.5, 5, 7.5 and 10%. A total of 360 specimens, 180 specimens each for the UCS and STS tests, were prepared in accordance with their optimum moisture content and maximum dry unit weight and cured for 7, 14 and 28 days. The study revealed that adding rubber fibres (up to 2.5%) to clayey soil leads to marginal improvement in UCS and STS. Note that by inclusion of rubber fibres to cemented clayey soil causes a decrease of UCS and STS. Maximum increase of absolute toughness and toughness index of cemented clayey soil was observed with the addition of 7.5% rubber fibres. Test results showed that inspite of the decrease in UCS and STS of cemented clayey soil with the augmentation of rubber fibre content, there were decreases in initial stiffness and improvements on ductility and hardening in the post-peak region. From this study, it could be concluded that rubber fibres up to 7.5% can be incorporated in the cemented clayey soil.

An experimental program was undertaken to study the effect of inclusion of pond ash and randomly distributed polypropylene fibres on the strength behaviour of cement-stabilized clayey soil. In the present investigation, 19 combinations of fibre-reinforced cement-stabilized clayey soil-pond ash mixes at three different percentages of pond ash (i.e. 10, 20 and 30%) and two different percentages of polypropylene fibres (i.e. 0.5 and 1%) of length 6 and 12 mm with 5% cement content were prepared. The combinations of clayey soil-cement-pond ash-fibres were subjected to a series of standard proctor test, unconfined compressive strength and split tensile strength tests. Based on favourable test results obtained, it can be concluded that partial replacement of cement-stabilized clayey soil by pond ash with the inclusion of polypropylene fibres causes a significant increase in strength, decrease in the stiffness, and rate of loss of post-peak strength. The fibre inclusion changed the brittle behaviour of the composite to ductile. The inclusion of 1% fibres of 6 mm length or 0.5% fibre of 12 mm length has the same impact on the unconfined compressive strength and split tensile strength of the mixtures. The study demonstrates that pond ash can be used successfully as partial replacement of the clayey soil by using reinforcement and cement.

The present study investigates the geotechnical characteristics of cemented clay-crumb rubber mixture through a series of compaction, UCS, STS, CBR, one-dimensional consolidation and swelling pressure tests. Crumb rubber (0.8–2 mm size) and cement content in the mixtures were 0%, 2.5%, 5%, 7.5%, and 10%, and 0%, 3%, and 6% by the dry weight of the specimens, respectively. The results of experimental research indicated that incorporation of crumb rubber in cemented clayey soil decreases the UCS and STS but prosperously able to overcome the brittleness of cemented clay in compression and tension. The CBR values of the composite having 6% cement were found to be propitious for its use as road sub-base with light traffic. It was also noticed that crumb rubber helps in reducing the swelling pressure and compression index of the mixes, which make it is a good candidate for lightweight fill material behind the retaining walls and embankment construction. Incorporation of crumb rubber in uncemented and cement clayey soil potentially reduces the reinforcement cost and deteriorating impact of waste tire disposal on the environment.

In a comprehensive laboratory study, different tests namely, standard Proctor tests, unconfined compressive strength (UCS) and split tensile strength (STS) tests were performed for evaluating the compaction and strength behaviour of the cement-stabilized, and sodium hydroxide treated coir fibre reinforced clay-pond ash mixtures. The treated coir fibres and pond ash of 0.5–1.5% and 10–30%, respectively, were added to the stabilized cement (2% and 4%) clayey soil. A series of compaction tests were carried out for studying the compaction characteristics. The cylindrical specimens of dimension 38.1 and 76.2 mm were prepared at desired densities and cured for 7, 14, and 28 days, after which they were, subjected to a series of unconfined compressive strength and split tensile strength tests. The investigation showed that the dry unit weight of the mixtures decreases and water content increases with the addition of pond ash and fibres. The inclusion of fibres and pond ash in the cementitious clay caused an increase in the unconfined compressive strength, split tensile strength and axial strain at failure. Compared with the clayey soil, the incorporation of pond ash (10%) and treated coir fibres (1%) in the cement-stabilized clay with 4% cement content improved the unconfined compressive strength and split tensile strength, i.e. 3.72 and 3.83 times growth in unconfined compressive strength and split strength respectively. The incorporation of treated coir fibre reduced the stiffness, rate of loss of post-peak strength and changed the behaviour of the composite from brittle to ductile.

The original version of this article unfortunately contained a mistake. The name of the second author was spelled incorrectly. The correct name of the second author is “Shaik Hussain.”