Cement mix for injection into very long annular gap, e.g. for sewer repair - contains Portland cement, liquidiser and lead cpd. to stabilise viscosity without impairing green strength and final strength

摘要

Hydraulic binding injection material consists of a mixt. of cement (I) with 50-100% Portland cement (IA) and cement additives, comprising naphthalenesulphonic acid polycondensate (IIA) with a deg. of condensation of n = 5-10 as liquidiser (II) and opt. 0.4-2.0 (wt.)pts. antifoam (III) and up to 0.05 pt. blowing agent (IV). It is made ready for injection by mixing with water. The novelty is that 1-10 pts. cpds. (V) are added. Amts. are w.r.t. 1000 pts. (I) throughout. Pref. (V) are basic Pb carbonate (VA) (2PbCO3.Ph(OH)2), Pb-2 acetate (Pb(CH3COO)2.3H2O) or Ob 2,4-oxide (Pb3O4), esp. 1-3 pts. (VA). (II) is a mixt. of (IIA) and a sulphonic acid-modified acetone/HCHO condensate (Na salt) (IIB) in 1:2 to 2:1 ratio, pref. in an amt. of 7-10 pts. (I) has a Blaine value less than 5500 cm2/g. (IV) is Al powder and (III) alkoxylated fatty acid esters. Up to 10 pts. microsilica (VI) may be added. USE/ADVANTAGE - The material is esp. suitable for restoring sewer pipes laid with little gradient, where it is usually necessary to inject the mix into a gap ca. 10 mm wide between the inner liner and wall of the pipe. Great lengths can be filled from a single injection point, since (V) stabilise the viscosity for a long period without impairing the green strength. Hydrostatic pressure can be used for filling.