Process to seal structural joints

A structural joint is sealed with the aid of an injection hose including a substantially liquid-impermeable base body which envelops a passage channel and which has exit openings distributed over the length of the base body for passage of injection liquid from the passage channel into the joint to be sealed. The exit openings open under internal excess pressure and I close under internal negative pressure. Following injection of the injection liquid into the joint to be sealed, the injection liquid remaining in the injection hose is drawn off from the passage channel.

BACKGROUND OF THE INVENTION 
The invention relates to a process to seal structural joints with the aid 
of an injection hose comprising a substantially liquid-impermeable base 
body which defines a passage channel and which has exit openings 
distributed over the length of the base body for the passage of an 
injection liquid from the passage channel into a joint to be sealed. 
The reliable and permanent seal of construction or expansion joints in 
structures, especially in concrete structures, presents a general problem. 
Due to the lack of space and traffic problems, construction is done 
increasingly underground, especially in densely populated areas. Typical 
examples are underground garages or underground streets. The reliable 
function and stability of these structures are largely dependent on their 
tightness with respect to penetrating water, and for this reason the 
majority of such structures currently are built of water-impermeable 
concrete. The concrete structure must ensure, in addition to its basic 
supporting and enveloping function, the function of satisfactory sealing. 
In so doing, the configuration and design of the construction and 
expansion joints thereof become important with regard to tightness and 
impermeability. 
Conventional joint guarantees frequently do not fulfill the demands imposed 
on them, resulting in considerable costs for cleaning and/or repairing 
leaky joints or cracks. For this reason, injection hoses of the type 
specified in DE-OS 35 12 470, DE-OS 33 20 875 and DE-GM 84 25 518 were 
developed to be built into the construction joints and through which an 
injection liquid is injected into the joint region in order to ensure that 
it will be water-tight. The injection process employs an injection hose 
and occurs usually when the curing of the concrete and thus the relaxation 
behavior typical of such building material has terminated. The injection 
liquid is injected into a passage channel of a substantially 
water-impermeable base body of the injection hose, from which it can issue 
through exit openings into the vicinity of the joint. The exit openings 
are covered as shown in DE-OS 25 12 470 or by means of strips that are 
made of compressible material and that are embedded in depressions 
disposed on the outside of the base body. The injection hose is held 
together by means of a hose or covering that is made of a liquid-permeable 
material and that envelops the base body and the strips. Owing to the 
injection pressure, the strips are compressed and the joints between the 
depressions and the strips are expanded in such a manner that the 
injection liquid can issue from the injection hose. Then the injection 
liquid can be left to harden, resulting usually in the joint being sealed 
by means of the injection liquid that has issued from the injection hose. 
However, the injection liquid also hardens in the hose interior, and it is 
impossible to check the quality of the seal. If in the course of time the 
interior of the structure shifts and thus the imperviousness of the joint 
is lost or, for example, the concrete cracks due to an overload, it no 
longer is possible to again pressure grout into the joint or crack, since 
the joint or crack no longer is accessible with the injection hose. 
Occasionally, it also happens that during initial pressure grouting the 
joint had large cavities or leaks, into which or through which large 
amounts of injection material have escaped laterally. Due to resultant 
pressure loss, the injection material could not reach all such joint 
regions, and porosity of the joint remained. In such case also, with the 
known method of using injection hoses it is not possible to seal 
subsequently the joint and check the joint seal for completion. 
SUMMARY OF THE INVENTION 
Therefore, the object of the invention is to ensure the quality and/or be 
able to check the seal of a joint formed by injection of an injection 
liquid, even over a prolonged period of time. 
This object is achieved by the invention in that the injection hose used 
has exit openings that open under internal excess pressure and that close 
under internal negative pressure, and that, following injection of the 
injection liquid into the joint to be sealed, the injection liquid 
remaining in the injection hose is drawn off before the liquid hardens. 
It is possible to draw off the injection liquid from the injection hose, 
for example an injection hose according to DE-OS 35 12 470, because the 
strips covering the exit openings are pulled shut on the base body by the 
negative pressure that is generated while drawing off the injection 
liquid, thus sealing the injection hose with respect to the joint. 
Therefore, injection liquid that issued from the hose during the previous 
injection process remains outwardly of the hose, even though it is still 
liquid, in the joint and is not drawn off with the liquid from the 
interior of the hose. 
After the injection liquid located in the injection hose is drawn off, the 
passage channel is free again and the injection hose is available for 
another injection operation. By means of a post-injection of injection 
liquid, the joint regions that were not completely filled during the first 
injection operation can be filled immediately following the first 
injection operation. But post-injection also can be conducted after a more 
or less longer period of time, should the joint have been demonstrated to 
be porous or in the course of time new cavities or cracks are to be filled 
and sealed with injection liquid. Even the injection liquid remaining in 
the injection hose during the post-injection operation can be drawn off 
again from the injection hose under the same conditions as during the 
first injection operation, so that the hose is available for reuse. 
After emptying the injection hose of the injection liquid following the 
first or subsequent injection operation and hardening of the injection 
liquid in the joint to be sealed, it is also possible to introduce water 
under specific pressure (for example by connecting to a water line a 
public supply network) into the injection hose. In this manner the 
imperviousness of the joint can be checked. Such checking for 
water-tightness can also be repeated at arbitrary time intervals. 
So that a reinjection operation or an operation of testing or checking for 
imperviousness is not prevented by residual injection liquid that has 
remained in the injection hose and, having hardened, plugged the hose, it 
is important to remove the injection liquid as completely as possible from 
the injection hose. This can be done, according to the invention, in an 
advantageous manner by means of application of partial suction pressure. 
To remove completely the residual injection liquid remaining in the 
injection hose from the hose, the injection hose can also be rinsed with 
water and/or compressed air can be blown therethrough after the injection 
liquid has been drawn off. 
The post-injection operation effected according to the invention, in order 
to seal totally or reseal the construction joints immediately after the 
injection liquid has hardened in the joint region or after a prolonged 
period of time, is carried out advantageously at a higher pressure than is 
the first injection operation. It has turned out that by means of such 
post-injection operation at raised pressure, even previously non-injected 
regions in the vicinity of the injection hose or even small pores or 
structural defects can be filled individually. 
The imperviousness of the joint can be checked or tested with water under 
pressure, preferably according to the invention in such a manner that the 
pressure is maintained over a prolonged period of time, for example for a 
few days. Thus, a reliable judgement concerning the imperviousness of the 
joint can be made. 
In accordance with another preferred feature of the invention, synthetic 
resins which harden reactively and can be mixed with water, resins based 
on vinyl ester, polyurethane resins, or ultrafine mortar with liquid 
additives can be used as the injection liquid. Even epoxy resins are 
suitable. Desired are injection materials which swell when stressed with 
water, thus additionally supporting the sealing of the joints and cracks. 
This swelling can be almost reversed by drying out the injection material. 
Injection liquids based on silicate mortar with hardening systems suitable 
for a particular application also are conceivable. Both vinyl ester-based 
resins and ultrafine mortar are water soluble in the fresh state, so that 
emptied injection hoses and apparatuses easily can be cleaned by rinsing 
with water and are then available again for post-injection, which may or 
may not be necessary, or for checking or testing the impermeability of a 
joint. Polyurethane resins that also can be used as the injection liquid 
are not water soluble. Therefore, they are post-injected, according to the 
invention, preferably only within the curing time thereof. With this 
injection medium the hose system is less easy to clean. It is within the 
scope of the invention to use different injection liquids for the 
individual injection operation.

The sole FIGURE is a cross sectional view of an injection hose which can be 
used preferably for the process of the invention. 
DETAILED DESCRIPTION OF THE INVENTION 
An injection hose 1 includes a base body 2 having a substantially hollow 
cylindrical wall and thus defining a central cylindrical passage channel 3 
that extends over the length of the hose. Injection liquid can be 
introduced into the passage channel 3 from one or both ends of the 
invention hose 1 or optionally also at connections provided between the 
ends, in order to distribute the injection liquid over the length of a 
joint that is to be sealed and is assigned by the injection hose 1. Four 
depressions 4, 5, 6 and 7, which extend over the entire length of the base 
body 2, are provided at identical angular intervals around the 
circumference of the base body 2. To produce a flow connection between the 
passage channel 3 and the depressions 4, 5, 6, 7, the hose wall has radial 
openings 8, 9, 10 and 11, which are distributed over the length of the 
hose and which open, on the one hand, into the passage channel 3 and, on 
the other hand, into the depressions 4, 5, 6 and 7. Disposed in the 
depressions 4, 5, 6 and 7 are respective strips 12, 13, 14 and 15, which 
are made of a reversibly compressible material and whose shape is 
complementary to the shape of the depressions 4, 5, 6 and 7. The base body 
2 and the strips 12, 13, 14 and 15 which are disposed in the depressions 
4, 5, 6 and 7 and which have outer surfaces substantially flush with the 
outer circumference of the base body 2, are enveloped by a hose 16 made of 
a thin liquid-permeable material or a material that dissolves under the 
effect of the injection liquid. In this manner the strips 12, 13, 14, and 
15 are held securely in their depressions 4, 5, 6 and 7, even if the 
pressure of the injection liquid is applied from the inside. Concrete 
components are reliably prevented from penetrating from the outside 
through the openings 8, 9, 10 and 11 into the passage channel 3, since 
with the pressure raised from the outside the strips 12, 13, 14 and 15 
merely close even better then openings 8, 9, 10 and 11 that are arranged 
in longitudinal rows. If, in contrast, the injection liquid pushes from 
the passage channel 3 from the inside outwardly against the strips 12, 13, 
14, and 15, such strips are compressed due to the nature of the material 
thereof, and the joints between the surfaces bordering the depressions 4, 
5, 6 and 7 and the strips 12, 13, 14 and 15 are expanded in such a manner 
that the injection liquid can issue from the injection hose 1 uniformly 
over its length and its circumference into the joint to be sealed. 
Following hardening of a building material, e.g. concrete, defining a joint 
and following completion of the relaxation behavior typical of the 
building material, injection liquid is injected into the passage channel 3 
of the injection hose 1. The injection liquid flows through the exit 
openings 8, 9, 10, 11 into the surrounding environment of the joint, in 
order to seal the joint. Following such injection, the not yet hardened 
injection liquid remaining in the injection hose 1 is drawn off by 
application of a negative pressure through the passage channel 3. In so 
doing, the strips 12, 13, 14, and 15 lying in the depressions 4, 5, 6 and 
7 are pulled inwardly due to the negative pressure generated within base 
body 2 and thus close the openings 8, 9, 10 and 11. Thereby, the interior 
of the injection hose 1 is sealed with respect to the joint, and the 
injection liquid that has escaped from the injection hose during injection 
is not sucked back into the injection hose 1. The injection material is 
sucked out of the injection hose 1, e.g., with a vacuum system. 
Subsequently, the injection hose 1 is rinsed with rinse water until the 
rinse water is clear and no longer exhibits any traces of injection 
material. Thereafter, compressed air is blown through the injection hose 1 
in order to remove as completely as possible the rinse water from the 
injection hose 1. Thus, the hose is suitable for post-injection 
operations. 
After the original injection liquid which has escaped into the joint region 
has hardened, e.g. after two hours, further injection liquid can be 
post-injected. By the application of fresh grout of such post-injection 
operation, other joint regions, which remained eventually without any 
grout and which the original injection material could not yet reach, e.g. 
due to leaks during the first injection process, can be filled. Then the 
injection hose 1 is cleaned again in the manner described above. Following 
hardening of this injection liquid in the joints, a further post-injection 
operation can be conducted, but preferably at a raised pressure. In this 
manner, previously non-injected regions in the vicinity of the injection 
hose 1 can be filled individually, even small pores or structural defects. 
Following emptying of the injection hose 1 of injection liquid, joints can 
be tested with water for imperviousness. To this end, water is injected 
into the emptied injection hose 1 preferably with a pressure corresponding 
to the construction site. The pressure is maintained over a prolonged 
period of time, e.g. several days. Leakages in the construction joints can 
be recognized by the eventual escape of water. If such leaks occur, 
further sealing can be effected with injection of material during renewed 
post-injection operations. 
Water-miscible, reactively hardenable synthetic resins, vinyl ester-based 
resins, ultrafine mortar with liquid additives, polyurethane resins, 
silicate mortar-based liquids can be used as the injection liquid. The two 
first aforementioned injection liquids are water soluble in the fresh 
state, so that emptied injection hoses and apparatuses can be cleaned by 
rinsing with water and are then perfectly suitable for post-injection, 
should it be necessary. Polyurethane resin is not water soluble, so that 
cleaning the injection hose 1 is difficult. Such injection resin should be 
post-injected within its curing time, i.e. before the polyurethane 
hardens. For individual injections, various different injection liquids 
are used. Furthermore, the volume of the injection resin can be increased 
by swelling upon contact with water, thus achieving additional reliability 
with respect to the later expansion of the joints, e.g. through settling. 
With the process according to the invention, construction joints with a 
width greater than 0.1 mm can be sealed.