A new generation of self-healing detectable grouts

Lead Research Organisation: University of Strathclyde
Department Name: Civil and Environmental Engineering

Abstract

Billions of tons of cement are injected into the ground world-wide each year to increase ground strength and to create barriers to water flow. Examples of its use in construction include building foundations, reservoir dams and tunnel walls. This activity is termed 'permeation grouting'. Use of permeation grouts are recorded as far back 1802, when cement grout was injected into holes in the ground beneath a sluice at Dieppe to stabilise the foundations, which were failing. More recently, £5M was spent injecting over 42,000 tonnes of cement grout into the ground to stabilise mine workings for the construction of the Emirates Arena and the Sir Chris Hoy Veladrome for the 2014 Commonwealth Games in Glasgow. Whilst technology has substantially improved over the last two centuries, the basic principles of cement grouting have remained largely the same.

A key aim of this project is to revolutionise the grouting industry by developing the first 'detectable' grout. A fundamental issue with all grout injection is the inability to detect where the grout has gone once it has been injected into the ground. This lack of knowledge can result in significant grout wastage, drilling of unnecessary wells, a lack of data for efficient injection and an inability to detect 'gaps' in grout walls where containment of water is critical; for example in dams and surrounding waste disposal sites.

The ability to detect the location of grout beneath the ground, both during and after grout injection will transform industry practice. It will allow for more efficient design of grout walls, will reduce the risk of un-grouted 'gaps' in the rock through which water can leak, and will minimise the volume of cement needed. Cement production accounts for 5% of the worlds CO2 emissions to the atmosphere each year, hence this research will have a positive impact on meeting global climate emission targets.

Planned Impact

Grouting campaigns can represent a significant environmental and financial cost. Cement production globally is estimated to account for up to 5% of global CO2 emissions; 900 kg of CO2 are emitted for the fabrication of every ton of cement. For the 2014 Commonwealth Games, for example, 41,430 tonnes of cement grout was used to stabilise disused mine workings for construction of the Emirates Arena and the neighboring Sir Chris Hoy Veladrome in Glasgow, at a cost of over £5M and an environmental impact of >37 million tonnes of CO2 emissions. Both of the proposed new technologies have the potential to make a significant impact on the financial and environmental cost of grout curtains. The detectable grout will enable minimisation of cement use, as well as increasing the reliability of the grout curtain by identifying any rock volumes into which the grout has not penetrated. The strong, self-healing non-cementitious grout, combining microbially-induced mineral precipitation with silica sol, can lead to a more environmentally acceptable alternative to current ultra-fine cements. Both developments have the potential to secure a leading technological edge for UK-based industry if proof of concept can be achieved. In particular, the detectable grout has the potential to become commonplace within what is a global billion-pound construction industry.
 
Description We are looking to replace traditional cements for sealing cracks in rocks to create barriers to water flow. Cements have a high carbon footprint.
We have shown that we can use bacteria to precipitate minerals (calcium carbonate) to seal rock fractures instead. Calcium carbonate is natural mineral that is common the ground and is more environmentally friendly than cement.
Exploitation Route We are exploring taking this forward with industry.
Sectors Construction,Energy,Environment

 
Description This research is linked to that in the BANDD consortium, so the impacts are the same. The findings from this work have been used to propose a solution for restoration of the twelfth century Eglise Monolith, St. Emilion, France. This is a commercially in confidence project with the French ground engineering company Soletanche Bachy. The church is currently closed to the public due to concerns over structural safety; the building stone in the columns is sufficiently degraded as to be structurally unsound. We are proposing to inject bacteria and precipitate calcite to strength the existing building stone. A decision has not yet been made as to whether the proposal will be accepted. The findings from this research are also the subject of an ongoing partnership with BAM Nuttall. We are working to take the microbially induced calcite technology to market as a alternative to traditional ground improvement techniques and to rock fracture cement grouting. Additional funding has been secured from the Royal Academy of Engineering/BAM Nuttall (£475k to support a Professorial Fellowship) and the Construction Scotland Innovation Centre (£187k). The new technology could significantly reduce the carbon footprint of the construction industry.
Sector Construction
Impact Types Cultural,Economic

 
Description Delivering Enhanced Through-Life Nuclear Asset Management
Amount £2,160,698 (GBP)
Funding ID EP/R004889/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Academic/University
Country United Kingdom
Start 11/2017 
End 10/2022
 
Description Innovate UK - nuclear technologies call
Amount £587,000 (GBP)
Funding ID 44213-320262 
Organisation Innovate UK 
Sector Public
Country United Kingdom
Start 07/2015 
End 06/2018
 
Description Innovation award
Amount £187,000 (GBP)
Organisation Construction Scotland Innovation Centre 
Start 04/2018 
End 03/2020
 
Description Royal Academy of Engineering Professorial Fellowship
Amount £475,000 (GBP)
Organisation Royal Academy of Engineering 
Sector Learned Society
Country United Kingdom
Start 11/2017 
End 10/2022
 
Title Data for: "Microscale analysis of fractured rock sealed with microbially induced CaCO3 precipitation: influence on hydraulic and mechanical performance" 
Description "Contains spreadsheets that can be opened with Microsoft EXCEL (or similar): 1) Fig4-shear_data.xlsx X-ray CT reconstructed 3D TIFF stack used in Figures 3, S2, S7. Can be opened with free image processing software ImageJ (or similar): 1) FG2.tif (429 MB) 2) FG3.tif (263 MB) 3) FG4.tif (214 MB) X-ray data processed to produce aperture maps used in Figures 3 & S7. Can be opened with most image processing software (e.g. ImageJ): 1) FG2_aperture_map.tif (~10 MB) 2) FG3_aperture_map.tif (~10 MB) 3) FG4_aperture_map.tif (~10 MB) X-ray data processed in 3D TIFF stack format to produce aperture maps for the sensitivity analysis Figure S2. Can be opened with free image processing software ImageJ (or similar): 1) FigS2d_aperture_map.tif (100 MB) " 
Type Of Material Database/Collection of data 
Year Produced 2018 
Provided To Others? Yes  
Impact
 
Title Data for: "X-ray CT and multiphase flow characterization of a 'bio-grouted' sandstone core: the effect of dissolution on seal longevity" 
Description Raw X-ray CT data of the rock core. Data has been reconstructed with no further processing and is in .v2 format (can be opened with ImageJ and Matlab). Each directory is a separate scan and corresponds with the scan number of Appendix A Supplementary data, Table.S1. Where repeat scans were made, these are contained in sub-directories titled ""series1"", ""series2"" etc. 
Type Of Material Database/Collection of data 
Year Produced 2017 
Provided To Others? Yes  
Impact Unknown 
 
Description Collaboration with University of Stanford 
Organisation Stanford University
Country United States 
Sector Academic/University 
PI Contribution We are moving forward with several follow-on joint projects with Stanford. We will have research student exchange and will have access to their X-Ray CT scanner for a period of 1 year.
Collaborator Contribution Access to X-Ray CT scanner and multiphase flow apparatus.
Impact Journal paper currently in review. 4 joint PhD studentships 2 funded by strathclyde, 2 by Stanford
Start Year 2014