Materials of contruction Module 1 part 1

PCC Paving

Portland cement concrete

HMAC

Hot Mix Asphalt Cement (400F)

WMAC

Warm Mix Asphalt Cement (200-275F)

PCC Paving (Rigid pavement)

12-18 inches and 28-day cure before drivable

Erosion Control

Heavy Stones (rip rap placed along shorelines)

HMAC (Flexible)

3-5 to 8-14 inches (Same day within hours) used on highway.

Aggregate Base Rigid

(Coarse)

Aggregate Base (flexible)

Fine

Volume of aggregate in PCC

60-75%

Volume of aggregate in HMAC

80-90%

Natural aggregates

* Sand


* Gravel
* Limestone

Manufactured Aggregates

* RPCC- Recycled Portland Cement Concrete
* RAC- Recycled Asphalt Concrete
* Slag

Aggregate Geology

Igneous→ Cooling magma (Extrusive, Intrusive)- Granite Basalt

Sedimentary → composition, crystallization heat and pressure (Limestone, Sandstone)

Metamorphic → already formed rocks given heat and pressure (Marble)

LA Abrasion Test

Acceptable abrasion values between 30-60% (Testing toughness of aggregate)

Freeze Thaw Durability

* “D” cracking
* Pop out

Aggregate Durability-Chemical-Alkali Silica Reaction (ASR)

A reaction between hydroxy ions in the alkaline cement pore solution in concrete & reactive forms of silica in the aggregate

Mechanical properties compressive

Strength of concrete or asphalt cannot exceed the strength of aggregate. Compressive strength of 5,000 to 50,000 psi

Void

Inter particle space

Pore

Intra particle space

Aggregate Properties (Physical)

* Physical


* shape & Texture
* Moisture
* Sp. Gr &UW
* particle Size distribution

Aggregate Properties (Mechanical)

Compressive

Aggregate Properties (Durability)

* Mechanical
* Chemical

Oven Dry (OD)

Dried in oven to Constant mass WOD

Dry SSD

Possible Stock Condition WStock

Saturated Surface dry (SSD)

moisture condition WSSD

Wet of SSD

Possible Stock Condition WStock

%MC

=Wstock- Wod/Wod\*100

%AC

WssD-Wod/ Wod\*100