Soil stabilization

About: Soil stabilization is a research topic. Over the lifetime, 3161 publications have been published within this topic receiving 48437 citations.

Immobilization of Heavy Metals in Contaminated Soils—Performance Assessment in Conditions Similar to a Real Scenario

Abstract: Soil “health” is becoming an increasing concern of modern societies, namely, at the European level, considering its importance to the fields of food, clean water, biodiversity, and even climate change control. On the other hand, human activities are contributing more and more to induce contamination in soils, especially in industrialized societies. This experimental work studies different additives (carbon nanotubes, clay, and Portland cement) with the aim to evaluate their effect on heavy metals, HMs (lead, cooper, nickel, and zinc) immobilization in a contaminated soil in conditions similar to a real scenario. Suspension adsorption tests (fluid-like condition) were performed aiming to supply preliminary information about the adsorption capacity of the soil towards the different HMs tested, while percolation tests (solid-like conditions) were performed aiming to evaluate the HMs immobilization by different additives in conditions similar to a real situation of soil contamination. Results showed that soil particles alone were able to retain considerable amounts of HMs (especially Pb and Cu) which is linked to their fine grain size and the soil high organic matter content. In conditions of good dispersion of the additives, addition of carbon nanotubes or clay can rise the HMs adsorption, except in the case of Zn2+ due to its low electronegativity and high mobility. Moreover, the addition of cement to the soil showed a high capacity to immobilize the HMs which is due to the chemical fixation of the HMs to binder hydration products. In this case, HMs immobilization comes associated with a soil stabilization strategy. The results allow to conclude that the additives, carbon nanotubes and clay, have the potential to minimize HMs mobility in contaminated soils and can be a valid alternative to the usual additive, Portland cement, when tested in conditions similar to a real on-site situation, if the objective is not to induce also soil stabilization, for instance, to enable its use for construction purposes. The results obtained can help designers and decision-makers in the choice of the best materials to remediate HMs contaminated soils.

Reactions and Strength Development in Portland Cement-Clay Mixtures

Abstract: THE ULTIMATE GOAL WAS TO GAIN INSIGHT INTO THE REACTIONS OCCURRING IN PORTLAND CEMENT-SOIL MIXTURES SOILS OF THE FREDERICK, IREDELL, AND LLOYD SERIES COMMONLY FOUND IN VIRGINIA WERE INVESTIGATED THE EFFECT OF THEIR CHEMICAL, MINERALOGICAL, AND ENGINEERING PROPERTIES AND SOIL WEATHERING STAGE ON SUCH PROCESSES AS THE DETERIORATION OF THE SOIL CONSTITUENTS, THE PRODUCTION AND CONSUMPTION OF CALCIUM HYDROXIDE, AND STRENGTH DEVELOPMENT OF THE MIXTURES IS DISCUSSED INVESTIGATIVE TECHNIQUES USED INCLUDED X-RAY DIFFRACTION AND MICROSCOPIC ANALYSES, AND CHEMICAL ANALYSES OF WATER (FOR CALCIUM) AND HYROCHLORIC ACID (FOR SILICON, ALUMINUM, AND IRON) LEACHATES OF THE MIXTURES THE FREDERICK SOIL CONSTITUTENTS DID NOT APPRECIABLY REACT WITH THE CEMENT, ALTHOUGH SOME OF THE CLAYS IN THE SOIL WERE SLIGHTLY DETERIORATED AFTER CEMENT TREATMENT THE CLAYS AND PROBABLY OTHER CONSTITUENTS IN THE B-AND C-HORIZONS OF THE IREDELL AND LLOYD SOILS SUFFERED DETERIORATION AFTER CEMENT TREATMENT, AS INDICATED BY THE RELEASE OF LARGE AMOUNTS OF SILICA AND ALUMINA AND BY THE DIMINUTION OF MINERAL X-RAY PEAKS WHEN THE MAJOR CLAY MINERAL IN THE SOILS WAS CONSIDERED, THE SOILS SUFFERED DETERIORATION AFTER CEMENT TREATMENT FROM GREATEST TO LEAST IN THE FOLLOWING ORDER: MONTMORILLONITIC SOILS, KAOLINITIC SOILS, ILLITIC SOILS THE INSTABILITY OF THE C-HORIZON IREDELL SOIL CONSTITUENTS IN A CEMENT SYSTEM APPEARED RELATED TO MINERALOGY THE MINERALS WERE NOT GREATLY WEATHERED AND WERE SUSCEPTIBLE TO THE HARSH CONDITIONS OF AN ALKALINE ENVIRONMENT THE GREATEST QUANTITIES OF CALCIUM HYDROXIDE WERE CONSUMED WITH KAOLINITE AS THE DOMINANT CLAY MINERAL IT APPEARS THAT REACTION OF CALCIUM HYDROXIDE WITH THE SOIL CONSTITUENTS WAS DIRECTLY PROPORTIONAL, AND THE DEVELOPMENT OF STRENGHT WAS INVERSELY PROPORTIONAL, TO THE MAGNITUDE OF THE CLAY-SIZE FRACTION /AUTHOR/

Lime stabilization using preconditioned soils

Abstract: THE SCOPE OF THIS INVESTIGATION WAS TO STUDY THE DEVELOPMENT OF A NEW METHOD OF BASE CONSTRUCTION USING LIME STABILIZATION WITH A DIFFERENT CONCEPT THAN THE CONVENTIONALLY ACCEPTED ONES. IN THIS CONSTRUCTION METHOD, A FIRST APPLICATION OF LIME IS USED TO CONDITION THE SOIL CONSTITUENTS, A SECOND, TO STABILIZE THE CONDITIONED MATERIAL. THIS NEW METHOD WAS ADOPTED AFTER A STUDY OF DIFFERENT SOIL-LIME PROJECTS AND THEIR LABORATORY TESTS, THE MAIN OBJECTIVE BEING SUBSEQUENT FAILURES AND THEIR REASONS. ALL TESTS, AND FIELD EXPERIENCE, LED TO THE CONCLUSION THAT TO OBTAIN THE DESIRED PROPERTIES OF STABILIZATION WITH THESE TYPES OF SOILS THEY MUST BE TREATED WITH LIME BEFORE BEING STABILIZED AND MUST BE COMPACTED WITHIN 48 TO 72 HR AFTER THE SECOND APPLICATION OF LIME. A FURTHER TIME STUDY OF THE SOIL-LIME REACTION WAS MADE, BASED ON INFORMATION YIELDED BY THE SOIL CHARACTERISTICS TESTS. THESE TESTS REVEALED THAT LIME HAS AN INITIAL REACTION, TAKING PLACE DURING THE FIRST 48 TO 72 HR AFTER MIXING, AND A SECONDARY REACTION, WHICH STARTS AFTER THIS PERIOD AND CONTINUES INDEFINITELY. ALSO, AN INVESTIGATION OF MOISTURE-DENSITY RELATIONS OF SOILS POINTED OUT THE EFFECTIVENESS OF CONDITIONING BEFORE STABILIZATION. CONDITIONED MATERIAL PRODUCED HIGHER DENSITIES AT LOWER MOISTURE CONTENTS AFTER STABILIZATION. /AUTHOR/

Long-Term Durability of Ordinary Portland Cement and Polypropylene Fibre Stabilized Kaolin Soil Using Wetting–Drying and Freezing–Thawing Test

Abstract: Soft soil stabilization frequently uses cement, lime, fly ash, etc., but very limited studies were conducted on the long-term durability of stabilized soil. The present study deals with the long-term durability of commercially available kaolin soil stabilized with ordinary Portland cement (OPC) and polypropylene fibre using a much more realistic approach, where the effect of weathering action can be observed in each cycle. Laboratory investigations were conducted to find the percentage loss of stabilized soil during wetting–drying and freezing–thawing tests, which are used as a durability indicator of cement and cement–fibre-stabilized soil. The stabilized soil encounters seasonal cycles of monsoon and summer in long run of its service life, which is simulated in rapid harsh weathering cycles in a laboratory setup. Kaolin soil samples were stabilized using different percentages of cement and mix of cement–fibre combination and were subjected to 12 cycles of wetting–drying and freezing–thawing cycles separately to determine the percentage loss of soil in accordance with the ASTM standards. Results of wetting–drying tests indicate that kaolin soil stabilized with cement and fibre combination survived up to 12 cycles, but only 10% cement + 0.5% fibre was durable against wetting–drying test based on percentage loss. Results of freezing–thawing tests indicate that only the kaolin soil stabilized with 10% cement, 5% cement + 0.5% fibre, and 10% cement + 0.5% fibre survived up to 12 cycles and are durable against freezing–thawing test based on percentage loss which satisfies the Portland Cement Association’s durability specification.