Methods II Exam

Three kinds of shallow foundations

isolated pad footings, continuous strip, mat

Deep type of foundation is called?

high rise

Four types of pile materials

steel, concrete, wood, combo

Four methods of placement for piles

Driven, jetting, CIP, vibration

Three methods of load transfer

bearing, friction, sheet

Amount of bend in a wood pile

sweep

uniform top/bot in a wood pile

taper

Advantages of wood piles

a. long life if submerged

b. lightweight

c. available

d. inexpensive

e. high skin friction

disadvantages

a. susceptible to insects, fungi, rot

b. low allowable driving force

c. relatively low bearing capacities

d. limited length

Three types of cast in place concrete piles

1. Shell-less or augered 2. Shell or cased 3. Belled end bearing

Three types of precast concrete piles

1. shapes 2. post-tensioning 3. pressure treatment

Two types of steel piles

1. H pile 2. Tube

What is an H pile?

Equal strength both directions

What is a tube pile?

Open or closed bottom

Advantages of steel piles

High bearing capacity

Two disadvantages

can be misdirected by large bounders underground, need extra protection in salt water enviroments

Two composite pile uses

low water table, extend the length

Reinforced concrete covering over a group of piles

pile caps

To hold back water or lose material

cofferdam

deep excavations in poor soil conditions poured in sequence to hold back and stabilize the side of an excavation

slurry wall

Three types of form liners

wood, concrete, plastic

aesthetic or architectural function – gives a russification look

form liners

Four parts of the formwork

form sheathing (facing material), turnbuckles and bracing, snap ties, walers

Large sections of form assembled on the ground and “flow” by crane into position

gang forms

formwork that moves as the pour continues

slip forms

Methods for shoring up a slab, pouring, and continuing upward floor by floor with the previous floors supporting the weight of the next shore and pour sections above

shore and pour systems

Three types of shore and pour systems

scaffold shoring, wood shoring, pipe shoring

Temporary form in a footing, wall, or slab used to “stop” the pour at a designated location intended to be the starting point for the next pour.

pour stop/construction joint

Seven things that compose concrete mix designs

Mix ID number: name designated by the designer, Cured strength, Water to cement ratio, Weight of all components: water, aggregate and cement, Engineered allowable slump, Air content, Allowable admixtures

Compressive strength depends on which applications?

footings, piers, columns slabs, walls

A higher cement ratio in a mix design can give a better architectural appearance – polished or exposed slabs. Better workability = better finish given proper technique and skill. True or False?

True

How fluid or runny the concrete mix is

slump

how long the concrete has been mixed. Will start setting as soon as water is added

time

allowable water content can be a limiting factor: more water = higher slump = weaker concrete

water

water reducing admixtures also called plasticizers or super plasticizers – chemically increasing slump without adding water.

admixtures

concrete cast into a footing may not need to be as fluid and will have a lower slump – typically how high?

4’ 6”

pumped concrete or a long haul to the job may require added water or water reducing admixture to increase the workability of the mix – typically how much?

7”

What does a higher slump usually mean?

Longer setting time

Anything not aggregate, water or cement

admixtures

What does the admixtures NCA (non-chloride accelerator) do?

1% or 2% accelerator

What does the accelerator calcium nitrate do?

set accelerator

controlled size, micro air bubbles added to the mix to aid in freeze/thaw – expansion and contraction. Not ideal for exposed smooth finished concrete. Will spall the surface

air entrainment

structural admixture for less cracking, higher strength, and higher wearing surfaces. Can be architectural and structural in polished slabs or simply structural to aid or take the place of other reinforcement such as rebar or wire mesh

fiber

added into the mix to give an appealing integral texture

color or dyes

Five method of conveyance of concrete

redi mix trucks, pump trucks, trailer pumps, hopper crane, buggy

consolidating the concrete to remove air voids and give form facing material smooth finish

vibration

What does over vibrating cause concrete to do?

cement and aggregate separation

screeding and floating: 2x material to strike off the top and level our or power screed.

flattening

hand or machine troweling – walk behind power trowel or ride on trowel machine

finishing

Controlling how fast the concrete sets and at what temperature

curing

flooding a slab with water. Keep it wet keep it cool. Hot weather method for curing

water cure

spray on agent to chemical protect and seal the concrete as it cures

chemical cure

Helps retain heat in cold weather - control the temperature

blankets

ensuring the mix design is being met

testing and inspections

What do you need testing for/inspections?

slump, water content, air content, compressive strength, always check delivery tickets to make sure mix design is correct this is your job!