Harbor Dredge Materials
Introduction
Harbor Dredge Material (HDM) is a natural, clay, pozzolan material found on the seabed of ports world-wide. Dredging activities make this material abundantly available for reuse in the manufacture of ‘green’ cement and related products.
Activated for use as an admixture / component in a cement design mix by the environmentally friendly Hill Process, HDM can provide the scalable solution to cement production needs and the reduction of harmful GHG emissions.
The production of green cement made with HDM can also provide a scalable solution to the potentially harmful containment challenges of the vast quantities of this material.
The Use of Harbor Dredged Material
Resource Materials Testing Laboratory is one of several sources of pozzolanic certification of HDM. As a certified pozzolan, HDM is available for use as a Supplemental Cementitious Material.
HDM can replace the current usage of manmade pozzolan (fly ash, etc.) making it a green admixture. Current sources of manmade pozzolans are limited and diminishing.
The Hill Process: A Breakthrough Technology in Pozzolan Activation
The Hill Process (patent pending) uses a mechanical process to activate natural pozzolans for use as Supplementary Cementitious Materials in manufacturing cement. Without the use of heat, natural pozzolan material; including Harbor Dredge Material (HDM), is brought to a reactive state making them clean and green.
Although natural pozzolans were ‘created’ by the heat of a volcano and man-made pozzolans mimic this process through the use of high heat kilns, The Hill Process is an innovative technology that is used in activating all types of natural pozzolan. The current high-heat, GHG emitting , process of activating clays and other natural pozzolans is replaced by a ‘clean’ process that releases no potential toxins into the atmosphere. .
Illustration: Natural Volcano
Illustration 2: Artificial Volcano
Illustration 3: The Hill Process
Clays as Pozzolans / Supplementary Cementitious Material (SCM)
“Calcined clays are the only potential materials available in large quantities to meet the requirements of eco-efficient cement-based materials by reducing the clinker content in blended cements or reducing the cement content in concrete. More than 200 recent research papers on the idea of replacing Portland cement with large amounts of calcined clay are presented and discussed in detail.”
“The search for alternative materials to replace ordinary Portland cement has been the object of work that enhances the investigation of the use of pozzolanic materials and the reduction of the carbon footprint with supplementary cementitious materials. However, not all materials are available to meet the large-scale demand for cement replacement. A relevant exception is the calcined clay, a material found worldwide that, when subjected to appropriate heat treatment, presents pozzolanic reactivity and can be used as a supplementary material to cement.”
Pinheiro VD, Alexandre J, Xavier GC, Marvila MT, Monteiro SN, de Azevedo ARG. Methods for Evaluating Pozzolanic Reactivity in Calcined Clays: A Review. Materials (Basel). 2023 Jul 2;16(13):4778. doi: 10.3390/ma16134778. PMID: 37445092; PMCID: PMC10343760.
View article here: https://pubmed.ncbi.nlm.nih.gov/37445092/
“It is a well-established fact that activated clays can be used to blend with Ordinary Portland Cement as a Supplementary Cementitious Material . The Hill Process changes the currently accepted practice of heat activation -which emits vast quantities of HGH, to a clean, non-polluting solution that meets the need for a vast quantity of SCMs.”
Jaskulski R, Jóźwiak-Niedźwiedzka D, Yakymechko Y. Calcined Clay as Supplementary Cementitious Material. Materials (Basel). 2020 Oct 23;13(21):4734. doi: 10.3390/ma13214734. PMID: 33113987; PMCID: PMC7660299.
View article here: https://pubmed.ncbi.nlm.nih.gov/33113987/
Pozzolan Materials as Admixture for Cement / C618
“Pozzolans are the most often used mineral admixture in the modern concrete industry. The pozzolanic reaction occurs during the hydration process when the siliceous or siliceous / alumina components along with calcium hydroxide chemically combine together to form cementitious properties.
Pozzolan admixtures in concrete improve the workability with a lesser amount of water, it increases the resistance of concrete to attack by salts and sulphates, and it leaches out calcium hydroxide.”
Dodson, V.H. (1990). Pozzolans and the Pozzolanic Reaction. In: Concrete Admixtures. Springer, Boston, MA. https://doi.org/10.1007/978-1-4757-4843-7_7
Also see the Test Results in section #1, Resource Materials Testing, Test #1; for chemical makeup of C618 qualified pozzolans.
HDM Performance Testing: SAI and Ordinary Portland Cement
Harbor Dredge Material has been tested for Strength Activity Index (SAI) and certified to meet the ASTM C618, standards. Further testing by Neocrete Laboratories has shown that Harbor Dredge Material when used as a SCM can create a concrete stronger than Ordinary Portland Cement
See testing results below and in section #1, Resource Materials Testing, “Physical Analysis,” Test #1; for chemical makeup of C618 qualified pozzolans.
Recycled Harbor Dredge Material & Green Cement
In our world today, we use the term, ‘green’ to define many commodities that we use daily. Green delineates the ‘how’ a commodity is produced, and its attributes are the sum of its environmental benefits.
Construction materials (cement) can be accurately classified as green when it uses at least one recycled material as one of its components. Reusing activated Harbor Dredge Material as a Supplementary Cementitious Material is a scalable solution to meet the needs of a ‘green’ economy.
Harbor Dredge Materials -Benefits to Green Cement
Answers regarding Carbon in HDM
What type of carbon does HDM contain and is it detrimental to concrete? “There may be some carbon present in HDM, but not elemental carbon unless some coal fly ash was inadvertently spilled into the bay. …As far as carbon in concrete, carbon is present in many forms, usually referred to as ‘organic’ carbon and ‘inorganic’ carbon (elemental or skeletal / when present alone.”
“…elemental carbon can be compared to charcoal or activated carbon. This form is rarely found in natural pozzolans. On the other hand, …activated carbon is a problem in ‘ready-mixed’ concrete because it interferes with the air-entrainment process .
What is the source for carbon in HDM? “The most likely source of carbon found in HDM is from plants. This type of carbon is monitored by the ASTM 311 test for air entrainment in concrete. The total amount of carbon found in most HDM is 3.5% or less, this is not detrimental, and it may act as an air-entraining agent.
Dr Robert Smith, PhD. Resource Materials Testing, http://www.rmtiflyash.com/index.php
A Clean method of Drying of Harbor Dredge Material (HDM)
Harbor Dredge Material is a valuable ‘green’ resource for the industrial world, but conventional means of processing are expensive and potentially environmentally unfriendly. When processed without heat, HDM is an environmentally friendly, scalable solution for producing a Supplementary Cementitious Material for use in manufacturing cement.
“The popularity of heat drying of wastewater sludge has increased over the past several years because it can reduce sludge mass and volume…. However, drying sludge using conventional combustion-heated dryers is energy-intensive.
“The dryer (heat-pump) constructed was essentially a closed-loop air system. The air used for drying is dehumidified to recover the latent heat of vaporization, re-heated using the recovered heat, and recirculated in a closed environment. The closed-loop layout eliminates emissions of dust, malodorous gases, and volatile compounds, obviating the need for exhaust treatment otherwise required to meet environmental regulations.”
Read more here: https://iwaponline.com/wpt/article/15/2/404/73876/Heat-pump-drying-of-industrial-wastewater-sludge
Gang Yuan, Khim Hoong Chu; Heat pump drying of industrial wastewater sludge. Water Practice and Technology 1 June 2020; 15 (2): 404–415. doi: https://doi.org/10.2166/wpt.2020.029