Mechanical properties and fracture behavior of basalt and glass fiber reinforced concrete: An experimental study

Improving the mechanical properties of recycled concrete aggregate using chopped basalt fibers and acid treatment

Basalt-based fiber-reinforced materials and structural applications in civil engineering

https://www.tpbin.com/Uploads/Subjects/1271c4da-5b73-47fc-bae4-65c490f4412e.pdf

FRP-strengthened RC slabs anchored with FRP anchors

The growth in metal use in the past few decades raises concern that supplies may be insufficient to meet demands in the future From the perspective of historical and current use data for seven major metals—iron, manganese, aluminum, copper, nickel, zinc, and lead—we have generated several scenarios of potential metal demand from 2010 to 2050 under alternative patterns of global development We have also compared those demands with various assessments of potential supply to midcentury Five conclusions emerge: (1) The calculated demand for each of the seven metals doubles or triples relative to 2010 levels by midcentury; (2) The largest demand increases relate to a scenario in which increasingly equitable values and institutions prevail throughout the world; (3) The metal recycling flows in the scenarios meet only a modest fraction of future metals demand for the next few decades; (4) In the case of copper, zinc, and perhaps lead, supply may be unlikely to meet demand by about midcentury under the current

Resource Demand Scenarios for the Major Metals.

Use of basalt fibers for concrete structures

This paper presents results from a study of the bond characteristics of high-strength steel reinforcing bars that conform to ASTM A1035. In the study, a total of 69 large-scale beam-splice specimens were independently tested at 3 universities. Concrete with nominal strengths of 5000 and 8000 psi (35 and 55 MPa) were used. Maximum bar stresses were compared with predictions obtained using the bond equations in the ACI 318-05 code provisions and those proposed by ACI Committee 408. Maximum stress levels of 120, 110, and 96 ksi (830, 760, and 660 MPa) were developed in No. 5, No. 8, and No. 11 (No. 16, No. 25, and No. 36) bars, respectively, not confined by transverse reinforcement. The failure of beams with spliced bars not confined by transverse reinforcement was sudden and produced explosive spalling of the concrete cover over the entire splice length. Providing confinement for No. 8 and No. 11 (No. 25 and No. 36) spliced bars using transverse reinforcement allowed stresses of up to 150 ksi (1035 MPa) to be developed. The design equations in ACI 318 showed a large percentage of the developed/calculated strength ratios below 1.0, indicating they should not be used in their present form for development and splice design with high-strength reinforcing steel The ACI Committee 408 equation is more conservative and provides a reasonable estimate of the strength for both unconfined and confined splices using a strength reduction factor of 0.82 and design parameters (cover, spacing, and concrete strengths) similar to those used in this study.

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Bond Characteristics of ASTM A1035 Steel Reinforcing Bars

This study seeks to quantify the benefits of using high-strength steel for concrete reinforcement and provides experimental evidence of its high strength capabilities. Test results are presented of six large-size concrete beams reinforced with either conventional- or high-strength steel and tested up to failure. The beams were constructed without web reinforcement to evaluate the nominal shear strength provided by the concrete. The shear behavior, ultimate load-carrying capacity, and mode of failure are presented. The applicability of the current ACI design code to large-size concrete beams constructed without web reinforcement is discussed. The influence of the shear span-depth ratio, concrete compressive strength, as well as the type and the amount of longitudinal steel reinforcement is investigated. Findings indicate that using high-strength steel alters the mode of failure from diagonal tension to shear compression failure and results in higher shear strength compared with using conventional steel. Findings also suggest that the current ACI shear design provisions are unconservative for large-size concrete beams without web reinforcement. The expression needs to account for the size effect and reinforcement characteristics.

Shear Behavior of Large Concrete Beams Reinforced with High-Strength Steel

Durability and long term behavior of FRP/foam shear transfer mechanism for concrete sandwich panels

Introducing openings in existing reinforced concrete (RC) slabs can severely weaken the slabs because of the cut out of the concrete and reinforcing steel. This paper reports field tests on the use of carbon fiber-reinforced polymer (CFRP) composite strengthening techniques to restore the flexural capacity of RC slabs after having openings cut out in the positive moment region. The uniqueness of this study is that the tests were performed on an existing multistory RC building that was scheduled for demolition. Five tests on five different slabs were conducted using three different strengthening techniques—namely, externally bonded (EB) CFRP plates, EB CFRP plates with CFRP anchors, and near-surface mounted (NSM) CFRP strips—to determine the most effective system for strengthening. Test results showed that the three strengthening techniques increased the load-carrying capacity of the slabs with openings, with the NSM technique being more effective than the EB technique. However, the use of CFRP anchors to mechanically anchor the EB plates prevented complete detachment, and hence enabled the restoration of the slab to its full flexural capacity.

Hatem M. Seliem

Papers

Use of basalt fibers for concrete structures

Bond Characteristics of ASTM A1035 Steel Reinforcing Bars

Shear Behavior of Large Concrete Beams Reinforced with High-Strength Steel

Durability and long term behavior of FRP/foam shear transfer mechanism for concrete sandwich panels

Case Study on the Restoration of Flexural Capacity of Continuous One-Way RC Slabs with Cutouts