Investigation and Repair of Rain Damaged Concrete

Carrasquillo Associates investigated and characterized the surface distress occurring at an elevated post-tensioned concrete slab in a parking garage that is part of a high-rise building under construction in downtown Austin, Texas. CA’s investigation included an examination of the extent of distress or unsound concrete in an area within one level of the parking garage equal to approximately 10,000 square feet, where rain had affected the fresh concrete surface soon after it had been placed. CA conducted a site visit to the parking garage to perform a visual examination and condition survey, and to obtain core samples from the concrete deck. The cores were studied by a concrete petrographer, who determined the extent of rain damage within the depth of each core. CA utilized this determination in developing a repair plan for the affected concrete surface to restore its serviceability and long-term durability. This project provides an example of CA’s expertise in recognizing a structural or materials problem and its root cause, assessing how it will affect the structure, and offering a repair solution that efficiently and reliably restores the structure.

Residential Alkali Silica Reaction Distress Investigation

CA investigated a residential concrete foundation slab where the interior finished concrete floor exhibited visible distress consisting of exudations on the surface of the concrete. These exudations included some consisting of clear, sticky gel and others consisting of hardened, opaque-white deposits. CA completed a condition survey, elevation survey, and concrete core sampling on site. The condition survey showed concentrated distress at and immediately around the grade beams where the vapor barrier was discontinuous and little distress in the slab areas between grade beams. The petrographic examination of the cores found that the observed distress in the cores extracted from the distressed areas was the result of alkali‑silica reaction (ASR). In this case, the aggregate near the surface exuded the gel to the surface of the concrete. Due to the site grading in combination with the discontinuous vapor retarder, moisture was being transmitted through the concrete at the grade beams resulting in the ASR distress. The lack of ASR in the slab areas between the grade beams indicated that with adequate under-slab moisture-proofing, the concrete was performing adequately.

Warehouse Foundation Slab Distress

CA investigated claims of poor construction of a 160,000 sq. ft. warehouse foundation slab. CA completed a site visit to the warehouse to document and verify the general condition, geometry, and construction of the interior concrete slab on grade, exterior paving, and eastside retaining wall. CA completed a crack map of the interior, documented other forms of distress such as joint distress and honeycombing, documented the joint type, and measured the joint layout and depth. While completing the site visit, the removal and replacement of a portion of the interior slab on grade was being completed independent of CA’s work. CA observed portions of this work and examined select portions of the slab on grade which were removed to determine concrete thickness and reinforcement location and depth. CA developed alternative repair strategies for the observed distress.

Forensic Investigation of Exterior Brick Masonry Deterioration

Carrasquillo Associates investigated widespread distress in exterior brick masonry at two residences in Midland, Texas. CA reviewed, evaluated, and synthesized extensive literature pertaining to brick mineralogy and deterioration mechanisms in order to fully understand the many facets and possible root causes of the observed distress and ongoing mechanisms of deterioration. CA conducted multiple site visits to study, observe, and document the brick masonry deterioration and to obtain numerous brick samples from the exterior residential façade and landscaping features. Several brick samples were subsequently tested for physical properties according to ASTM standards, including absorption and compressive strength. The chemical composition and mineralogy of several specimens were studied using x-ray fluorescent (XRF) and x-ray diffraction (XRD) techniques in order to comprehensively investigate the types of raw materials used in production and to assess the degree of vitrification achieved during brick firing. This project provides an example of CA’s expertise in deciphering the contributing players in material degradation, such as brick masonry deterioration, and displays CA’s ability to manage material testing through multiple laboratories for one particular study or project.

Forensic Engineering Investigation & Analysis of Bridge Overlay Failure

The Pulaski Skyway Bridge Project consisted of a steel truss bridge supporting a concrete bridge deck with repairs where the top 1.5 inches of concrete bridge deck was replaced with a latex modified concrete topping along the entire length. Shortly after, the repairs began to exhibit premature failure in the form of reflective cracking around the perimeter of the repaired area, then debonding, followed by cracking of the patch repair material causing eventual potholes in the bridge deck. CA’s investigation involved, among others, review of daily log reports, expert reports, and other relevant documents, and a site visit during which a visual condition survey was performed to determine the cause(s) of the observed premature patch repair failures in the bridge deck.

Structural Analysis & Investigation of Retaining Wall Failure in Houston

CA was retained to investigate the failure of a retaining wall at a refinery in Houston, Texas, assess the original design and structural adequacy of the wall for its intended purpose, and to determine the cause(s) of the failure. CA’s investigation consisted of reviewing and evaluating construction related documents, including plans and drawings, contract documents, review of legal documents and correspondence, review of expert reports submitted by all parties, review of structural plans and a structural analysis of the structure.

Repair and Rehabilitation of Cooling Basin

A cooling basin constructed as an addition to an existing co-generation cooling system consisted of cast-in-place concrete with walls approximately 60 ft. tall. Shortly after the cooling basin was constructed, the owner expressed concerns that the basin was leaking. CA was retained to observe the repairs performed to the basin walls by a third party hired and to certify that all repairs were performed according to industry standards of practice. CA’s activities included numerous site visits, non-destructive testing, evaluation of existing conditions, and observed on-site testing by other parties. CA provided the client with additional repair options and procedure recommendations.

Forensic Investigation of Light-Rail Track

The project consisted of cast-in-place, concrete pavement, light-rail track sections at road intersections in Seattle, WA. The pavement system at the road intersections consisted of a bonded overlay system made up of 12 in. thick portland cement concrete pavement bottom layer with a 5 in. thick bonded topping layer. CA was retained to investigate and determine the cause(s) the observed the distress which consisted of hairline cracking in the bonded topping layer of the pavement. CA’s investigation included the review of construction documents and several site visits to perform detailed condition surveys including photographic documentation. CA determined the cause of the distress and recommended repair and remediation options.

Concrete Materials Consulting & Structural Analysis for Christopher Columbus Statue in Puerto Rico

Located atop a hillside on the northern shores in the city of Arecibo, Puerto Rico, a Christopher Columbus Statue is being erected and is projected to be completed by late summer of 2015. The Statue consists of over 2,000 exterior pieces of copper and bronze connected to an interior structural steel frame for a total weight of over 600 tons. The structure was originaly designed by Russian sculptor Zurab Tsereteli in 1991 to commemorate the 500th anniversary of Columbus’ 1492 arrival to the Western Hemisphere. CESG’s contribution to the project included consulting services in regards to the mat concrete foundation consisting of the structural design, project specifications’ development, material condition assessments, and construction management. In addition, CESG’s project involvement also included the development of the concrete mixture proportions, concrete placement sequencing, quality control, temperature and maturity monitoring, and implementation of early age protection to the mass concrete elements. Over 1,500 cubic yards of concrete were placed in approximately 8 hours of which all concrete loads were accepted, there was no evidence of cracking with in the mat foundation mass concrete elements, and all the concrete compression strength tests exceeding the 28-day specified design strength in 7 days.

Continuously Reinforced Concrete Pavement Interstate Highway Concrete Crack Repair

This project consisted of conducting a forensic investigation into the cause(s) of the observed random cracking in the continuously reinforced concrete pavement (CRCP) highway sections of Loop 375 in El Paso, Texas. During this investigation, CA conducted a visual inspection of the CRCP sections exhibiting distress, performed an examination of the concrete pavements being investigated, reviewed reports from other investigators, evaluated the concrete production records, and reviewed construction related documents including weather conditions and construction daily reports. The observed distress consisted primarily of random plastic shrinkage cracking. Findings indicated that high evaporative weather conditions, lack of protection of the concrete surface, and poor concrete curing practices contributed to the distress observed. Partial depth and full depth cracks were repaired at CA’s direct using a high molecular weight methacrylate crack sealer. Removal and replacement of the distressed concrete was not necessary.