The Indirect Tensile Strength (ITS) was used to characterise the soil stabilising
properties of a urea-formaldehyde (UF) resin. The test soil was brown shale gravel.
Synergistic strength improvements were obtained when combining the resin with
anionic bitumen emulsion and dosing both at 2%. Performance levelled off above
these concentrations. For full strength development, the soil moisture content must
be reduced to below 3%. Optimum indirect tensile strength is obtained at
formaldehyde to urea molar ratio of 2:1. Soil strength increases as the reaction pH is
lowered but the need for adequate application times restricts it to pH > 4,5. The
experimental results also suggest that the presence of appropriate organic matter is
critical for effective soil stabilisation with UF resin.
Die Indirekte Treksterkte (ITS) is gebruik om die
grondstabilisasie-eienskappe van ‘n urea-formaldehied hars (UF) te kwantifiseer. Die
toetsgrond was ‘n bruin skaliegruis. Kombinasie van die hars met ‘n anioniese
bitumen emulsie toon sinergistiese sterkteverbetering wanneer beide doseer word op
die 2% vlak. Werkverrigting plat af bokant hierdie konsentrasies. Vir volle sterkteontwikkeling
moet die grondvogtigheid verlaag word tot onder 3%. Optimale indirekte
treksterktes word behaal met ‘n formaldehied-tot-urea molverhouding van 2:1.
Grondsterkte neem ook toe soos die reaksie pH verlaag word maar vir pH < 4,5 word
die beskikbare aanwendingstyd ontoereikend. Die eksperimentele resultate dui ook
daarop dat die teenwoordigheid van ‘n geskikte organiese fraksie in die grond krities
is vir effektiewe stabilisasie met UF hars.
