Current methods to improve the engineering properties of sands are diverse with respect to methodology, treatment uniformity, cost, environmental impact, site accessibility requirements, etc. All of these methods have benefits and drawbacks, and there continues to be a need to explore new possibilities of soil improvement, particularly as suitable land for development becomes more scarce. This paper presents the results of a study in which natural microbial biological processes were used to engineer a cemented soil matrix within initially loose, collapsible sand. Microbially induced calcite precipitation (MICP) was achieved using the microorganism Bacillus pasteurii, an aerobic bacterium pervasive in natural soil deposits. The microbes were introduced to the sand specimens in a liquid growth medium amended with urea and a dissolved calcium source. Subsequent cementation treatments were passed through the specimen to increase the cementation level of the sand particle matrix. The results of both MICP- and ...

Microbially Induced Cementation to Control Sand Response to Undrained Shear

The GPR (Ground Penetrating Radar) conference in Hong Kong year 2016 marked the 30th anniversary of the initial meeting in Tifton, Georgia, USA on 1986. The conference has been being a bi-annual event and has been hosted by sixteen cities from four continents. Throughout these 30 years, researchers and practitioners witnessed the analog paper printout to digital era that enables very efficient collection, processing and 3D imaging of large amount of data required in GPR imaging in infrastructure. GPR has systematically progressed forward from “Locating and Testing” to “Imaging and Diagnosis” with the Holy Grail of ’Seeing the unseen’ becoming a reality. This paper reviews the latest development of the GPR’s primary infrastructure applications, namely buildings, pavements, bridges, tunnel liners, geotechnical and buried utilities. We review both the ability to assess structure as built character and the ability to indicate the state of deterioration. Finally, we outline the path to a more rigorous development in terms of standardization, accreditation, and procurement policy.

A review of Ground Penetrating Radar application in civil engineering: A 30-year journey from Locating and Testing to Imaging and Diagnosis

Microbial-induced calcite precipitation (MICP) is a novel ground improvement method to increase strength and stiffness of sand using natural biogeochemical processes. Cementation level and confining pressure are two important factors that control the behavior of MICP sand. The monotonic mechanical response of MICP cemented sand is systematically investigated using four cementation levels (untreated, lightly treated, moderately treated, and heavily treated) and three levels of effective confining pressure (100, 200, and 400 kPa). The results indicate that the stiffness, peak shear strength, and dilation increases with an increase in calcite content at a given effective confining pressure and the dilation is suppressed with an increase in effective confining pressure. This behavior is consistent with soil-like behavior; therefore, all the MICP soils presented herein are evaluated using critical-state soil mechanics and not an analogous fracture-mechanics framework. The experimental results also indi...

Influence of Confinement and Cementation Level on the Behavior of Microbial-Induced Calcite Precipitated Sands under Monotonic Drained Loading

A technique of cementing porous materials artificially using calcite is presented The technique depends on flushing a mixture of chemical solutions through a porous medium, leading to precipitation of calcite due to reaction of the solution ingredients The experimental procedures adopted to achieve the cementation are described The response of different soils to the cementation process is analysed The bond mechanism created by the calcite is illustrated, using optical and electron micrographs The paper discusses the factors that appear to determine the response of geomaterials to calcite treatment It has been found that the strength of a calcite-treated material increases with: (a) intrinsic strength of the individual grains, (b) density, (c) decreasing particle size of the host grains, (d) pre-coating of grains with calcite, and (e) roundness and non-angularity of soil grains The cementation technique described in this paper has proved successful in reproducing the mechanical behaviour of natural 

Cementation of porous materials using calcite

bons, hydrocarbon polymers, ethylene copolymers, styrenics, acrylics, polyacrylonitrile and copolymers, other C-C main chain polymers, polyethers, polyamides, polyesters, main chain aromatics, and polymer blends. Data for approximately 200 polymers are presented. Each sample is fully identified as to origin, molecular weight, molecular weight distribution and treatment immediately before the test. Specific volume under ambient conditions is also given for each polymer. This book is a careful and complete compendium of pressure-volume-temperature data of polymers.

Mechanics of porous continua

Calcium carbonate cementation of sand: A method for producing artificially cemented samples for geotechnical testing and a comparison with natural cementation processes

The purpose of this paper is to present long-term measurements in a full-scale study on a basal reinforced piled embankment that make it possible to validate calculations used for the design of the...

Long term measurements in the Woerden geosynthetic-reinforced pile-supported embankment

Rapid and Non-intrusive Measurements of Moisture in Road Constructions Using Passive Microwave Radiometry and GPR – Full Scale Test

Infrastructure is the backbone of our society. Citizens, companies and governments have come to rely on and expect uninterrupted availability of the road network. Extreme weather is an important factor for the reliability of the road network. At the same time it is generally understood that the climate is changing and that this will have significant effects on the road infrastructure. Since road infrastructure is vital to society, climate change calls for timely adaptation. Immediately, questions arise how to deal with the large uncertainties involved in the projections of future climate, how to assess their effects on the road infrastructure and related socio economic developments, and how to integrate adaptation into decision making. The ROADAPT project was commissioned under the CEDR Call 2012 ‘Road owners adapting to climate change’. It adopts a risk based approach using the RIMAROCC framework (Risk Management for Roads in a Changing Climate, developed under a previous ERA NET ROAD project). The approach addresses cause, effect and consequence of weather-related events to identify the top risks that require action with mitigating measures for climate change adaptation. Output of the ROADAPT project is a single ROADAPT-RIMAROCC integrating guideline.

Arjan A.M. Venmans

Papers

Calcium carbonate cementation of sand: A method for producing artificially cemented samples for geotechnical testing and a comparison with natural cementation processes

Long term measurements in the Woerden geosynthetic-reinforced pile-supported embankment

Rapid and Non-intrusive Measurements of Moisture in Road Constructions Using Passive Microwave Radiometry and GPR – Full Scale Test

Climate Change Risk Assessments and Adaptation for Roads – Results of the ROADAPT Project☆

Total engineering geology approach applied to motorway construction and widening in the Netherlands: Part II: Pilot site in tidal deposits