Sulfuric Acid Test

Effects on Concrete Subjected to Sulfuric Acid

INTRODUCTION:

A claimed use of DRYCRETE Moisture Stop is as a protective barrier in Portland cement concrete wastewater structures.

Previous sulfate expansion testing has shown promising results.

A more aggressive, quick indication was desired to gauge the effectiveness of DRYCRETE Moisture Stop against attack from sulfur-based corrosives.

Figure 1: Sulfuric Acid Attack Cycle On Concrete (from Girardi)

EXPERIMENT:

Four concrete specimens, approximately 1 year of age, and approximately measuring 3” x 3” x 4” were obtained. These specimens had previously been exposed to flexural strength testing and had 4 to 6 fractured faces. The fractured faces and assumed accompanying micro-cracking were chosen to allow easier access for the corrosive solution. Beginning masses of each sample were determined.

Two of the samples were treated with DRYCRETE Moisture Stop and two were not. The samples were allowed to sit for 24 hours before testing. All four were submerged in a 3 molar concentration of sulfuric
acid ( H2SO4 ) for 26 hours.

Samples were removed, rinsed with tap water, dried by hotplate, and masses determined.

 

Figure 2: Test Setup

RESULTS:

Within five minutes of introducing the samples into the sulfuric acid, differences were observed between the control and experimental groups:

Notice the activity of the control (untreated) vs the relative inactivity of the treated sample as evidenced by bubbles.

Samples were removed at 26 hours, dried, and mass loss determined:

  BEGIN END  
Sample # Mass (g)  Mass (g)  % Loss 
1 (control) 718.6 708.2 1.45%
2 (control) 734.0 722.9 1.51%
3 (treated) 746.0 741.8 0.56%
4 (treated) 608.7 605.4 0.54%
Figure 4: Mass Loss Results – Approximately a 63% Mass Loss Reduction

 

Figure 3: Five (5) minutes into testing

 

PHENOLPHTHALEIN (pH) TESTING RESULTS:

Samples were broken open and subjected to a spray phenolphthalein (Rainbow Indicator by German Instruments.)

 

Specimen 1 & 2 are from the untreated cores and specimen 3 & 4 are from the treated cores.


 

 

Figure 5: pH Indicated By Phenolphthalein On Split Samples

 

 

 

CONCLUSIONS:

The samples treated with DRYCRETE Moisture Stop showed approximately 63% less mass loss than the control samples.

The pH gradient of the interior of the samples demonstrates that DRYCRETE Moisture Stop treated samples are retarding the ingress of acid and/or not allowing the acid to react with the interior of the concrete.

 

Figure 6: Closeup Of Sample 3 Showing pH Gradient

   

 

Note: The tests were conducted by the reputed moisture testing company Flood Testing Laboratories, Inc. in Chicago, Il. All tests were performed on site, under normal exterior atmospheric conditions during a period of heavy precipitation with record rainfall recorded during the month of June 2011.

Meets or exceeds the following testing criteria and guidelines

ASTM C-67 Section 7: Water Absorption
Water absorption of treated concrete was decreased by at least 90%.

ASTM C-67-Section 9: Suction
The rate of absorption of concrete (suction) was decreased by as much as 98%.

ASTM C-67-Section 10: Efflorescence
Efflorescence and leaching are eliminated.
 
ASTM C-67-Section 65: ORF Method, Dusting Resistance
Treated concrete is four times more abrasion (dusting) resistant.
 
ASTM C-672-760: Scaling resistance to Deicers
Treated concrete imparts excellent resistance to salt attack.
 
ASTM C-666: Freeze Thaw Resistance
Significanty Improves resistance to freeze-thaw damage.
 
ASTM C-856: Petrographic Analysis
Specimens have at least 50% greater density, which results in reduced permeability.
 
ASTM C-1585: Rate of Absorption of Water by Hydraulic Cement Concrete
Demonstrates a measurable reduction in water absorption after treatment of the concrete block.
 
ASTM D-2047: Slip Resistance
Wet and Dry testing showed that treated concrete had a much improved slip resistance.
 
ASTM E-96: Moisture Vapor Transmission
An effective barrier against water vapor emission, without loss of breathability reducing vapor emission by > than 75%.
 
ASSHTO T259-80: Chloride Ion Penetration
Reduces chloride intrusion in hardened concrete.
 
Reduces the depth of water penetration by 94%
 
CRD C-48-73: Hydrostatic Pressure Resistance
Sealed specimens at 45 psi, the equivalent of 115 ft of standing water while field testing has shown efficacy at near 300 ft.
 
CRD-52-54: Abrasion Resistance
Significantly increased abrasion resistance.


USDA Approved For Use in Food Processing Areas & EPA Compliant
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PREVENT BLUSHING

Whitening of concrete sealers – also known as ”Blushing”
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PREVENT SPALLING

When the water in concrete is able to freeze, it then expands & causes damage to concrete surfaces.
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PREVENT MOISTURE ISSUES

Leaves no surface residual to impede or hinder bonding of any coatings or adhesives.
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PREVENT EFFLORESCENCE

A white crystalline powder-like substance which forms on surface of concrete, stucco, brick or masonry.

PERMANENT CONCRETE PROTECTION

DRYCRETE is a product of Concrete Earth
601 N. 5th Ave • Kankakee, IL 60901
1-800-441-6646 • 630-257-5060 • 630-257-9006 FAX