<instructions>Your goal is to analyze the following comment and estimate how highly it will be upvoted by the Hacker News community.</instructions><comment><author>philipkglass</author><text>&lt;i&gt;The report exposes quite the paradox: We desperately need these infrastructure projects to transition to a carbon-neutral world, but in doing so we will have to emit a massive amount of carbon.&lt;/i&gt;&lt;p&gt;Massive compared to &lt;i&gt;what&lt;/i&gt;? This article highlights that a single wind turbine uses a lot of concrete. But per the latest IPCC assessment, wind power over its life cycle already has the &lt;i&gt;lowest&lt;/i&gt; median CO2 emissions of any electricity source. Sure, look for even cleaner ways to make materials, but this rhetoric is terrible. It lets fossil shills bludgeon you with your own words later: &amp;quot;see, environmentalists say coal burning emits massive amounts of carbon dioxide, but they say the same about switching to wind power, so there&amp;#x27;s no rush to change things.&amp;quot;&lt;p&gt;Here&amp;#x27;s a recent review article about curbing CO2 emissions from cement:&lt;p&gt;&lt;i&gt;Global strategies and potentials to curb CO2 emissions in cement industry&lt;/i&gt;&lt;p&gt;&lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;s3.amazonaws.com&amp;#x2F;academia.edu.documents&amp;#x2F;39977040&amp;#x2F;1-s2.0-S0959652612006129-main.pdf?AWSAccessKeyId=AKIAIWOWYYGZ2Y53UL3A&amp;amp;Expires=1530469511&amp;amp;Signature=iO7NNWFleA6%2F%2F8NF2ta4wIRigTA%3D&amp;amp;response-content-disposition=inline%3B%20filename%3DGlobal_strategies_and_potentials_to_curb.pdf&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;s3.amazonaws.com&amp;#x2F;academia.edu.documents&amp;#x2F;39977040&amp;#x2F;1-s...&lt;/a&gt;&lt;p&gt;It provides actual numbers and suggestions. Only half of cement&amp;#x27;s CO2 emissions per ton come from the chemistry inherent in calcining calcium carbonate to produce calcium oxide and carbon dioxide. The rest comes from the fossil sources of energy used to process materials. Like most industrial processes, it can cut emissions significantly just by switching input energy sources. Also, as someone else mentioned, concrete absorbs atmospheric CO2 as it cures. It&amp;#x27;s mostly the fossil combustion embedded in its production that drives emissions over its full life cycle.</text><parent_chain></parent_chain></comment><story><title>Are we stuck with cement?</title><url>https://theoutline.com/post/5124/are-we-stuck-with-cement-environmental-impact</url></story>
<instructions>Your goal is to analyze the following comment and estimate how highly it will be upvoted by the Hacker News community.</instructions><comment><author>madaxe_again</author><text>This article talks as though Portland cement is the only cement. It isn’t.&lt;p&gt;I’ve spent the past few years working in my free time on the restoration of several old buildings, under the guidance of my wife, who is a conservation mason, much of which has comprised removing cement and gypsum plaster and replacing them with lime mortar, lime plaster, and other lime products as appropriate.&lt;p&gt;While it’s true that most lime products aren’t as strong as cement, and are permeable to water vapour, their CO2 impact is much, much smaller - and many applications which currently see the use of Portland could as easily use appropriate lime-based products. Breathability is a &lt;i&gt;good&lt;/i&gt; thing in most structures - most damp that you see in buildings arises from impermeable materials and condensation.&lt;p&gt;As to strength, lime-Portland blends exist which can create impermeable and strong concrete with less environmental footprint, and I’ve been experimenting with mixing lime with various different aggregates and plasticising agents - resulting in some interesting materials - ground pumice and slate in varying proportions produce very strong (high tensile and compressive properties) and impermeable materials - I was inspired by Roman concrete.&lt;p&gt;Here’s a tiny bit of further info on CO2 footprints, from a company I’ve bought several tonnes of NHL from:&lt;p&gt;&lt;a href=&quot;http:&amp;#x2F;&amp;#x2F;ecolime.co.uk&amp;#x2F;c02-quick-facts&amp;#x2F;&quot; rel=&quot;nofollow&quot;&gt;http:&amp;#x2F;&amp;#x2F;ecolime.co.uk&amp;#x2F;c02-quick-facts&amp;#x2F;&lt;/a&gt;</text><parent_chain></parent_chain></comment><story><title>Are we stuck with cement?</title><url>https://theoutline.com/post/5124/are-we-stuck-with-cement-environmental-impact</url></story>