By CA User 0 Comments

Concrete Strength Analysis of a Rural Bridge Deck

The project consisted of the rehabilitation of a 165 ft. long rural steel girder bridge. The concrete bridge deck was to be replaced with a cast-in-place, high performance concrete deck to be supported by the existing steel beams. During the final days of construction, CA was retained to determine the cause of the low concrete strength test results and slow early-age concrete strength gain. CA’s forensic engineering investigation included the review of quality control strength test results and concrete production data, extraction and testing of concrete core samples, a petrographic examination, and a general assessment of the concrete surface quality. CA’s investigation contributed to opening the bridge to traffic only several days after the investigation was completed.

By CA User 0 Comments

Investigation into the Cause of Cracking in Precast Post-Tensioned Concrete Beams

The construction of Highway 10 in Puerto Rico has been one of the largest and longest highway projects in the island. This highway runs through Puerto Rico’s scenic mountains and was expected to be completed in 2015. Cracking in the precast, post-tensioned concrete beams manufactured on-site resulted in concerns to the public authorities requiring immediate action. CA provided construction consulting services during construction of various post-tensioned concrete beams and sections of Highway 10. CA inspected many of the beams where cracking was observed, visited the concrete production facilities on-site, observed casting operations, and evaluated field data including, but not limited to, internal concrete temperatures of the concrete beams. In addition, CA’s investigation included a review of concrete mixture proportions, material information, concrete quality control testing results, curing, and demolding practices to determine the causes of the concrete cracking observed and propose remediation procedures.

By CA User 0 Comments

Power Plant Scrubber Mass Concrete Foundation

The project consisted of a cast-in-place reinforced mass concrete foundation at a power plant in Texas. The foundation was 94.5 ft. in diameter, nine (9) ft. thick, contained two (2) mats of reinforcing steel consisting of four (4) layers of large diameter (No. 11) bars, approximately 2,600 cubic yards of concrete, and was supported by 339 piles for the addition of a 525 ft. tall reinforced concrete chimney. The structural integrity and capacity of the foundation was questioned due to owner observed construction defects during concrete placement. CA’s investigation included, among others, review of structural concrete design calculations, a finite element structural analysis model to evaluate internal stresses, non-destructive testing of concrete, core sampling, assessment of the concrete production methods and logistics, and  numerous site visits to conduct field investigations and condition assessments totaling over 1,400 man-hours. CA’s extensive investigation uncovered the cause(s) of the distress and structural deficiencies.

By CA User 0 Comments

Indoor Concrete Topping Placement Recommendations

Construction at a university recreation and wellness center required a concrete topping slab in the main entrance and lobby areas. CA provided structural engineering consulting services including, but not limited to, improvements to the concrete placement activities and incorporation of necessary measures to reduce the potential for drying shrinkage cracking. CA’s experience with concrete toppings and understanding of concrete placement fundamentals contributed to successfully addressing the project’s needs and its unique conditions. CA provided recommendations for the concrete placement including reducing structural restraint and bond, implementing drying shrinkage cracking control and appropriate curing methods, and using proper joint design and layout.

By CA User 0 Comments

High School Cast-in-Place Concrete Crack Investigation

A high school in Bellaire, TX consisted of a cast-in-place, reinforced concrete, slab-on-ground with intermediate grade beams and drilled piers. CA was retained to investigate distress that included cracking in the floors and walls in several buildings of the high school. CA performed, among others, a general condition survey, photographic and schematic documentation, and a relative elevation survey of the floor. CA also evaluated original plans, drawings, and project specifications for comparison with the as-built structure. The quality of concrete was also examined to determine the presence of any construction defects or deficiencies in the concreting operations.

By CA User 0 Comments

Apartment Complex Parking Lot Pavement Assessment

CA was retained to investigate the cause(s) of the distress observed in the concrete pavement parking lots at a complex in Murphy, Texas. The complex was comprised of four buildings and each had one or two concrete pavement parking lots surrounding it that were connected with inner drives throughout the complex. The parking lots consisted of both heavy and regular duty pavements. CA’s site visits consisted of performing a detailed survey of the cracked areas in the pavement including photo documentation, collection of concrete cores and soil samples, and observation of the demolition of selected areas of pavement. The results from the forensic examination of the concrete cores, soil samples, and construction records provided the necessary data for CA’s expert opinions regarding concrete repair methods for the pavement areas.

By CA User 0 Comments

Litigation Support for a Regional Waterline Project

CA served as a structural engineer expert witness after performing an extensive forensic engineering investigation into determining the possible cause(s) for the premature failure of a 48 inch diameter precast concrete section of a pipeline extending about 28 miles. The pipeline was built to feed raw water from Lake Stillhouse Hollow to Lake Georgetown, Texas. The investigation conducted included a condition survey of failed sections of concrete pipe, the evaluation of construction related documents, quality control sampling and testing of the soil, backfill, and pipe materials, structural analysis of the pipe design, and evaluation of the construction means and methods, among others.

By CA User 0 Comments

Warehouse Floor Forensic Investigation and Analysis

CA was retained to perform an evaluation of the structural integrity of a slab-on-grade warehouse floor exhibiting distress including cracking and spalling along the contraction joints and construction joints. Cracks appeared in the slab-on-grade, and spalling or flaking occurred near construction and control joints. Concern was also raised about the cracking in the mezzanine of the structure. CA engineers conducted a condition survey and performed non-destructive testing (NDT) for the entire complex, including the use of CA’s ground penetrating radar services.  Both the visual assessment and the NDT were performed to find the reason for cracking and to see if both the slab-on-grade and the mezzanine met specifications. CA’s forensic engineering investigation determined that the slab-on-grade and the mezzanine did in fact meet the specifications for the project. The test program showed that there was no structural or serviceability damage in either the slab-on-grade or the mezzanine and recommended options for fixing the cracks.

By CA User 0 Comments

Port of Valdez Marine Terminal Condition Assessment and Cost Analysis

This project involved the condition survey and life-cycle assessment of the three process facilities related to the ballast water treatment at the Valdez Marine Terminal located in Valdez, Alaska. CA conducted an on-site condition survey of the Gravity Separator Tanks, the Dissolved Air Flotation Facility, and the Biological Treatment Tanks, all of which exhibited evidence of significant deterioration. The condition assessment study included documentation of the distress present in the concrete substructures and structural steel superstructures of the three facilities including concrete non-destructive testing and concrete sampling. Concrete samples for chloride ion content testing, petrographic analysis, and corrosion testing were extracted and existing data from in-place cathodic protection systems was evaluated. Recommendations for structural repair and remediation related to the present condition and future serviceability of the facilities were prepared and a rehabilitation construction cost analysis was presented.

By CA User 0 Comments

Regional Health Science Center Cracked Concrete Repair

The Regional Academic Health Center is an extension of University of Texas at San Antonio Medical School located in Harlingen, Texas. During the construction of the first floor cast-in-place reinforced concrete elevated slab, significant cracking of the structural members occurred. CA was retained to investigate the cracked floor system and to determine whether remedial action was necessary. CA’s investigation consisted of a condition assessment and structural analysis of the floor system. CA determined the cracks to be cosmetic in nature and not structural. CA developed a concrete crack repair remediation plan consisting of sealing the cracks using a high molecular weight methacrylate. CA was responsible for supervising the concrete restoration services and verifying the performance of the repair.