DESIGN OF SURFACE SEALS

EXAMPLE $1(7)$

Situation

A section of road between Town A and Town B is to be resealed with a $13\mathrm{.}2$ mm single seal.

Details

Terrain:

Current Traffic:

Existing surfacing:

Texture depth

Rolling; maximum gradients of $5\%$ with slow$-$moving heavy vehicles travelling at $35k\frac{m}{h}$

Aggregate:

Heavy Vehicles $=\frac{75}{?}$ day $\frac{?}{?}$ lane

Light Vehicles $=\frac{500}{?}$ day $\frac{?}{?}$ lane

$9\mathrm{.}5$ mm single seal treated $3$ years ago with a fine slurry texture treatment

Texture depth is uniform on this section with an average of $0\mathrm{.}3$ mm

The aggregate delivered on site confirms to COLTO sepcifications ${?}^4$ with an ALD of $7\mathrm{.}9$ mm and a flakiness index of $15\%$

Binder: a $80/100$ penetration Grade Bitumen is selected, hot application rate $1\mathrm{.}09$

Nett cold binder required for a $0\mathrm{.}7$ m texture depth from $7$ mm and $8$ mm Single Seal Charts:

For $8$ mm ALD: min$1\mathrm{.}07\frac{e}{m^2}$max$1\mathrm{.}36\frac{e}{m^2}$

For $7$ mm ALD: min$0\mathrm{.}92\frac{e}{m^2}$max$1\mathrm{.}02\frac{e}{m^2}$

Adjustments

Existing texture depth, add $0\mathrm{.}19\frac{e}{m^2}$

Gradients: max $5\%.$ Reduce net cold binder by $5\%$ on up hills

Policies

A lean seal is preferred. Provide Minimum Application Rates only.

DESIGN

$1\mathrm{.}1$ Calculate ELV $/$ lane $/$ day

$(1)$

$1\mathrm{.}2$ Calculate the Nett cold binder required for a $0\mathrm{.}7$ m texture depth at the specified aggregate ALD. $(2)$

$1\mathrm{.}3$ Calculate the Nett cold binder required after adjustments $(2)$

$1\mathrm{.}4$ Calculate the hot binder application rate $(1)$

$1\mathrm{.}5$ Calculate the aggregate application rate $($See Annexure A$)(1)$