Cement and chemical Grouting
Injection technique is used in civil engineering to improve the mechanical and permeability properties of soil, rocks and brick or concrete work.
From a functional point of view, two types of interventions can be identified:
• temporary intervention, to make excavation possible in unstable soil or under water table;
• permanent intervention for the consolidation of foundation soils, the creation of watertight structures, or the structural restoration of brick or concrete works.
From an operating point of view, grouting is divided into loose soil grouting and in rock grouting.
Rock fissure grouting is performed directly into the open borehole. In this case, downstage or upstage methods can be used. In both cases, borehole inclination must be defined depending on the position of soil layers and the direction of discontinuities, so as to affect the highest number of joints or fissures.
Grouting in weathered rocks or loose soil can be performed by using tubes fitted with check valves, which are driven into the ground after drilling. The valves are usually rubber sleeves that cover lengths of the tube featuring holes: they inflate under pressure and force the grout through the holes preventing it from flowing back.
Cement-based grouts are usually the choice for rock formations or loose coarse-grained soils. Cement grouts can be stabilized by means of prehydrated bentonite, whereas they are made less cohesive and more fluid by adding special formulations and deflocculating-fluidifying additives (MISTRA grouts). There is evidence in literature that successful grouting depends in the first place on the size of the solid particles of the injected grout compared to the dimensions of the gaps or rock fissures to be injected.
Uhandisi wa cement na kemikali ya Grouting Injection hutumiwa katika uhandisi wa ujenzi ili kuboresha mali ya mitambo na uingizaji wa udongo, miamba na matofali au kazi ya saruji. Kwa upande wa kazi, aina mbili za uingiliaji zinaweza kutambuliwa: uingiliaji wa muda, ili kuwezesha uchimbaji katika udongo usio thabiti au chini ya maji ya chini ya ardhi; uingiliaji wa kudumu kwa kuimarisha udongo wa msingi, uundaji wa miundo ya maji, au ukarabati wa muundo wa matofali au saruji. Kutoka kwa mtazamo wa uendeshaji, grouting imegawanywa katika grouting ardhi huru na katika grouting mwamba. Rock ufa grouting ni kufanyika moja kwa moja katika shimo wazi. Katika kesi hii, downstage au upstage mbinu inaweza kutumika. Katika kesi zote mbili, mwinuko wa shimo lazima ueleweke kulingana na nafasi ya tabaka za udongo na mwelekeo wa kutoendelea, ili kuathiri idadi kubwa ya viungo au ufa. Grouting katika miamba weathered au udongo huru inaweza kufanyika kwa kutumia mabomba vifaa na valves kurudi, ambayo ni kuendeshwa katika ardhi baada ya kuchimba visima. Valves ni kawaida rubber sleeves kwamba kufunika urefu wa bomba featuring mashimo: wao inflate chini ya shinikizo na kulazimisha grout kupitia mashimo kuzuia ni kutoka mtiririko nyuma. Kwa kawaida, mchanganyiko wa saruji hutumiwa kwa ajili ya miamba au udongo wenye chembechembe. Cement grouts inaweza kuwa imara kwa njia ya bentonite prehydrated, wakati wao ni alifanya chini cohesive na zaidi mtiririko kwa kuongeza formula maalum na deflocculating-fluidifying nyongeza (MISTRA grouts). Kuna ushahidi katika fasihi kwamba mafanikio grouting inategemea katika nafasi ya kwanza juu ya ukubwa wa chembe ngumu ya grout injected ikilinganishwa na vipimo ya mapengo au mianya mwamba kuwa injected.