Combined Effect of Marble Waste as Powder and Aggregate Form on the Proprieties of the Mortar

Recycling and recovery of waste are now considered as a solution for the future to protect the environment. The marble processing workshops on the other hand, generate a large amount of waste in the form of powder and small parts. Due to these facts, the aim of this study is to valorize marble waste in the form of powder and crushed aggregates (sand) as additions in cementitious matrix building materials. The characterization of the materials used to formulate mortars based on natural dune sand with marble powder and mortars based on mixed sand (dunes sand and crushed sand) and marble powder was measure. In this sense, several series have been studied, varying the addition rate of the marble powder in order to reduce the porosity of the cement matrix, using crushed marble sand to increase the granular cohesion and using of a reducing water admixture (MEDAPLAST SP40) for more performance mortars. Very appreciable results were observed for a dosage of 15% of marble powder and for the combination of 15% of marble powder with 20% of crushed marble sand. This research recommends recycling 35% of marble waste in the cement matrix that contribute effectively to the preservation of the environment.

Strength properties of biopolymer treated clay/marble powder mixtures

Depending on their unique layer structures and chemical structures, soil problems such as swelling, settlement and loss of strength can be seen especially on clay soils when exposed to water. Settlement occurring on clay soils on which the structure is built, causes various damages in the building. Additionally, in the clay soil interacting with water, strength loss occurs due to the effect of the building load. Today, when soil improvement techniques are developed and diversified, clay soils can be stabilized by using different additives. A clay soil that has been improved by adding waste marble powder within the scope of this study in certain percentages (5%, 15%, 25%), biopolymer added clay / marble powder samples were obtained by interacting with locust bean gum in certain percentages (0.5%, 1%, 1.5%). There are many studies in the literature on improving clay soils using only marble powder or only biopolymer. In this study, marble powder and biopolymer were used together and thus, the feasibility of a more effective soil improvement has been investigated. The results showed that the unconfined compressive strength of the biopolymer added clay-marble powder mixtures are higher when compared with natural clay. Similarly, shear box test results showed that the unconsolidated-undrained cohesions and internal friction angles of the doped clay samples increased. It was observed that the strength values of marble powder-added clay increased after improving with biopolymer.

Management of Solid Waste Marble Powder: Improving Quality of Sodium Chloride Obtained From Sulphate Rich Lake/Subsoil Brines With Simultaneous Recovery of High Purity Gypsum and Light Basic Magnesium Carbonate

Marble industry worldwide produces large amount of non-degradable marble dust powder (MDP) waste during mining and processing stages. MDP mainly comprises of CaCO3 with small amounts of Mg, Fe or Si in various forms. In India, mainly in Rajasthan state, marble is quarried in huge amounts and MDP thus produced is collected improperly and dumped at any abandoned land or identified disposal sites leading to several environment hazards. On the other hand, the composition of sub soil/lake brines of Rajasthan is typical in nature as it does not have much Ca2+ and Mg2+ impurities but contains higher levels of SO42-. Therefore, the common salt (NaCl) produced from such brines is contaminated with Na2SO4 (8-30 wt%) depending upon SO42- concentration in the brine. Such a salt produced is neither suitable for edible purpose nor for industrial usage. Herein, we have reacted MDP with HCl, and the resulting solution (CaCl2 and MgCl2 slurry) is used in stoichiometric ratio of Ca2+ to SO42- in brines to produce high purity NaCl and gypsum (CaSO4·2H2O) via fractional crystallization. Remaining magnesium containing solution was reacted with Na2CO3 to prepare high purity light basic magnesium carbonate hydrate. Purity of crystallized NaCl, CaSO4·2H2O and MgCO3·6H2O has been ascertained through analytical and spectral methods (TGA, FTIR, P-XRD). Field emission scanning electron microscopy (FE-SEM) was used to elucidate morphology of crystals. The method reported for improving purity of NaCl along with CaSO4·2H2O and MgCO3·6H2O production from sulphate rich brines is simple and economic, and allow management of MDP generated in huge amounts, which poses problems of disposal and creates environment hazards.

Geopolymers as Alternative Sustainable Binders for Stabilisation of Clays—A Review

The need to transit to greener options in soil stabilisation has revamped research on the use of industrial and agricultural by-products in order to cut down on the current carbon footprint from the use of ordinary Portland cement (OPC) and lime related binders for the treatment of problematic soils. This study is a review on the use of geopolymers constituted by alkali activation of several industrial wastes such as pulverised fuel ash (PFA), ground granulated blast furnace slag (GGBS), metakaolin (MK), glass powder (GP), palm oil fuel ash (POFA), silica fume (SF), rice husk ash (RHA), volcanic ash (VA), and marble powder (MP) for the stabilisation of weak clays. The performance of stabilised clays as subgrade and subbase materials for road pavement construction was evaluated by comparing the 7 day UCS of the treated clays with the strength requirement for stabilised materials as outlined in BS EN 16907-4. The result of the study shows that geopolymers can be employed in improving the engineering properties of problematic clays to meet practical applications. Strength improvement was observed in the stabilised clays with increased precursor content, molarity of alkaline activator, and curing period.

Experimental Studies of Marble Concrete Prepared with Micro Silica and Rice Straw Ash

This experimental study is about the investigation of the concrete prepared with marble waste, micro silica and Rice Straw. Investigation is done by determining ad comparing the mechanical Strength properties and cost of Proposed concrete with the Normal conventional concrete. The different test on the marble concrete shows that the incrment in marble powder content increases the mechanical strength of concrete. Marble is costlier than the Coarse aggregate, so it also increases the cost of the concrete. Micro silica fills the voids in the concrete and helps in the increment of the strength. After the replacement of recycled aggregates and addition of the silica fume, Rice Straw ash can replace cement by 15% without any decrement in the strength of the concrete. Total water absorption of the concrete Decreases due to use of marble because it does not absorb any water.