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ETC 1250 Lesson 02d

# ETC 1250 Lesson 02d - Lesson#2d ETC125O Properties of...

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Unformatted text preview: Lesson #2d ETC125O - Properties of Materials - Chapter #2 - Pg 68 — 84 Tests - Surface Area - Surface Area to Volume Ratio of a quantity of aggregate is important: — In waste water fitters, organic matter is consumed by bacteria that live on aggregate surfaces. — If aggregate particles are to be bound together for strength, such as in concrete or asphalt Surface area = 4'11?l (4711" ) volume = 7’ Surface area Ratio = Volume Weight I Volume Relationships Density = v - Used to determine the volume of aggregate in relationship to its weight - The quantity needed is determined according to the volume it must occupy, but that quantity is ordered and measured for payment by weight Specific Gravity = SG - Used to determine the Solid Volume of Aggregate Introduction - Tests — Surface Area — Weight-Volume Relationships - Density - Specific Gravity - Voids — Deleterious Matter — Miscellaneous Properties - Sampling Tests - Surface Area - Particles that roughly approximate spheres have roughly the same surface to volume ratio — all other shapes have greater ratios - The larger the radius, then the smaller the Surface Area to Weight Ratio Surface area = 41."?2 I _ 4m” v0 ume — 3 Surface area _ Ratio = Volume Weight I Volume Relationships %Voids - In base material the voids between coarse aggregate particles are ﬁlled with ﬁne aggregate for stabilization - The volume of voids must be known to obtain the correct volume of ﬁne aggregate %Voids and Pores - In asphalt concrete, a percentage of the volume of the pores is filled with liquid asphalt material - Therefore, the correct quantity of asphalt cement for the mix includes enough to coat the particles plus enough to partially ﬁll the pores Weight / Volume Relationships k (Total) Volume (V) = . 1:”me id Mater + Pores + Voids -' 1M mm Saturated,SurfaceDryVo|ume Q Wssd): ' ' id Mater + Water in Pores id Volume Nod) = id Mater [Oven Dried) ule-uu .um. Iiwm Iai sot-cm— w‘u-iumw-«(M-w Wam- uwnnrwo imrwnnimuuuwoi .mn— Maui-u- we: nun-um ter + Water in Pores + Surface _- _ = - Saturated, Surface Dry Weight 6:9 ssd) = mun-lulu". och-mn- en Dry Weight (Wod) = rum-um mum “Hum-MN nun-um...- id Mater want"... u. unwni o‘ I!" am. Submerged Weight (Wsub) = ""‘"‘" Weight minus displaced water Density or Unit Weight — Example Calculate yd if an aggregate weighs 47.72 lb, has a moisture content of 6.3% (0.063), and occupies a volume of 0.498? W. where y = total density or unit weight (lblft3} W = weight of aggregate, including water (lb) V = volume (W) W = 47.72 lb V 0.4987 ft3 95.69 lblﬂ3 y = 95.69 lbl'l‘l3 90.02 lblﬂ3 1 + mc 1 + 0.063 Speciﬁc Gravity The ﬁrst two kinds of speciﬁc gravity listed are considered as a true speciﬁc gravity: 1 . Bulk speciﬁc gravity is based on ovewdry weight and saturated, surface—dry weight of the aggregate particles Bulk SG =Wod! (Wssd —Wsub) Apparent speciﬁc gravity is based on oven—dry weight and solid weight of the particles Apparent SG 2 Wodir [Wod —Wsub) . A type of speciﬁc gravity called effective speciﬁc gravity is used in the design of asphalt concrete Effective speciﬁc gravity = Wod (Wod —Wsub) + ‘E’nPore's Volume id Mater + Water in Pores “\$32533 ”swim. "".?.‘.;:L."..".‘J;.Tu'»'. Density (or Unit Weight) Terms Density or unit weight values for aggregates are expressed as - total density = y includes absorbed moisture - or dry density = yd. Weight (W) = measured weight, regardless of moisture content To calculate density we must know moisture content - Moisture Content (mc) = [[Wssd — Wod} } Wssd] Speciﬁc Gravity Whereas Density of a solid’s weight divided by it’s volume: Specific gravity is the ratio of density of a substance compared to the density of fresh water at 4°C (39° F) Since specific gravity is a ratio, so it has no units. — An object will ﬂoat in water if its density is less than the density of water (a speciﬁc gravity less than 1) and sink if its density is greaterthatthat ofwater (a speciﬁc gravity greater than 1) Speciﬁc Gravity - Example Wocl = Oven DryWeight= 5290g Wsub : Submerged Weight: 3450g Wssd : Saturated‘ Surface Dry Weight Z5480g Bulk SG =Wod:r (Wssd —Wsub) = 5290 H5480 — 3450) = 2.61 Apparent SG 2 Wod t [Wod —Wsub) = 5290 i’ (5290 —3450) : 2.88 ‘l’o Absorption = [(Wssd —Wod)tWod] x100% = [(5480 — 5290) i’ 5290] x 100% = 3 6% Voids - Calculate the percent solid volume and percent of voids in a ﬁne aggregate if it has an apparent speciﬁc gravity of 2.65 and a bull-( unit weight of111.3 lbl't’t3 Solid volume “it = UnitWelghtBuI x100% (565m x Unﬁtteightwm) Note: (SGEW x UnitWeightwm) 2 Unit lilteight‘,d 2111.3lbiW X10096 2.65 x 62.4 Ibit’ta = 613% % Voids = [SGE242 x Unit WeightNm} — Unit Weightgulkx 100% (SGEW x Unit Weight‘E) — Note: UnitWelghtod— UnitWeigntBulk= Unlttitteight‘m5 = (2.65 x 62.4Ibift3)—111.3|bift3 X1OD% [2.65 x 62.4 Ibiﬁl = 32.?% Tests - Deleterious Matter Lightweight pieces are particles in coarse or fine aggregate that have an SG substantially less than that of the aggregate as a whole Organic impurities are organic material, mainly tannic acid, sometimes found in fine aggregate Reactive aggregates are those which contain minerals which react with alkalis in Portland cement, causing excessive expansion of mortar or concrete Sampling & Testing Testing of samples is required for: - Preliminary investigation of a possible source of supply — Whether a rock formation, an aggregate deposit, or an industrial byproduct — The supplier makes this investigation before investing the money to extract and process aggregate - Acceptance or rejection of a source of supply by the buyer — Made by a prospective buyer who intends to buyr large quantities for one project or a series of projects — An example is a state public works department which approves or disapproves gravel or sand pits for state projects for the coming year or other period oftime Tests - Deleterious Matter - Frrabie particies are those which are easily crumbled between thumb and fore-ﬁnger Matenai finer than No. 200 sieve. Washed sieve analysis Soft particies are those that are marked with a groove after being scratched on a freshly broken surface by a pointed brass rod under a force of 2lb Miscellaneous Properties Toughness, which means resistance to abrasion and impact Soundness of aggregates means resistance to disintegration under weathering - Hydrophiiic aggregate "loves water“ — Hydrophilic aggregate does not maintain adhesion to asphalt when it becomes wet. Sampling & Testing ...And Testing of samples is required for: - Acceptance or rejection by the buyer of specified material from the supplier — Inspection and tests are performed as aﬁnal check for conformance to the agreement at the time of delivery - Control of removal and processing operations — The supplier assures himself that his product remains of consistent quality by testing rt Assignment . Page 85 Review Questions 10, 14, & 17 If you do not understand a question, email me at [email protected] or through myPHCCedu ...
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ETC 1250 Lesson 02d - Lesson#2d ETC125O Properties of...

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