Experimental evaluations of load carrying capacity of post installed steel anchors

In this research, the ultimate load capacity of post-installed anchors for three adhesives (three brands: HIT-RE10, ROX-GU80 and DUBELLF1331) and grouts (FLO-GROUT2) were evaluated experimentally and compared with the reference cast-in-place anchors. A parametric study was conducted to assess the effects of the anchor diameter (10, 12, 16 mm), anchor embedded length (5d_b,10d_b, and 15d_b), the cleaning method and drilled hole size on the adhesive and grouted anchors. Also, the effect of the saturation of the concrete on the pullout capacity for adhesive and grouted anchors had been studied.   

Among the used three adhesive brands, the anchor adhesive Brand “HIT-RE10” appeared to have the largest bond capacity. Furthermore, apart from the small embedded length (5d_b), the experimental results showed that the ultimate load capacity of the post installed anchors was higher than the reference cast-in-place anchors. In the same embedded length range (>5db), the average bond stress decreased with the increase in the embedded length. With respect to the effect of increasing the embedment length and the diameter parameters, the results showed that there is a corresponding increase in the ultimate load capacity of both the adhesive and the grout anchors.

For the cleaning method parameter in the adhesive anchors, cleaning with Method I (air only) achieved a higher ultimate load capacity compared with cleaning using Method II (air plus wire brush) because wire brush tends to polish the drilled surface; however, in grouted anchors, cleaning using Method I (air plus wire brush) produced the larger capacity than cleaning using Method (II) because wire brush tend to remove dusts that remain in the drilled holes that produce a weaker bond between the grout and the concrete

The results showed also that cleaning holes of the adhesive anchors by Method III (washing with water and wire brush) produced the highest ultimate load capacity compared with the other two cleaning method. 

Regarding the adhesive/grout thickness parameter, the ultimate load capacity, a part from the 5db embedment length, increasing adhesive thickness with (+4mm, +8mm and +12mm) resulted in a higher final bonding strength. This behavior was opposite in the grouted anchors, where there was a reduction in the ultimate load capacity with the increase of the grout thickness; this behavior was more pronounced at smaller depth (5db,10db) rather than large depth (15db).

Further, the adhesive anchors installed into wet saturated concrete have larger ultimate load capacity compared with the anchors installed into wet saturated concrete. Both of grouted and adhesive anchors ultimate load capacity increased when the anchors installed in saturated concrete but there was a drop in the ultimate load capacity of grouted anchor if it was installed into wet saturated concrete because it will increase the water / grout ratio. Also grouted anchors installed into dry concrete had lower ultimate load capacity compared to the grouted anchor that  installed into saturated concrete.