By markweaver66 August 29, 2013
Work done twice already due to poorly laid finishes. Both stamped concrete finishes peeled. Do yourself a favor and find a pro before you call Paul the owner. After several calls still no answer. He won't stand behind his work and he does very poor work. Still waiting for a call from him to fix what he's been paid for. Think twice before you call "contractor" like windy hill concrete Lancaster PA ...read more
What makes a great lime for true lime mortars? Higher calcium content leads to quicker carbonation and a more durable mortar. Magnesium and other impurities either don’t react or react slowly with CO2. But is high-calcium lime enough to make a good lime-only mortar? No. Food-grade calcium hydrate is pure, but does not have high surface area for CO2 reactivity. A calcium hydroxide slurry for deacidification is more likely to have high-surface area, but may not be high-calcium. Limes manufactured for Portland cement need to be “dead burned” (sintered) so the lime and Portland (hydraulic) reactions don’t compete. A “soft-burned” lime (maintained at 900°C) has a porous “coral-like” surface that is derived from firing the lime optimally to drive off CO2 (see below). Lime for Portland-based masonry mixes continues to be fired beyond this stage until the pores close up again. This material adds plasticity to stiff and brittle Portland, but would not provide porosity or reactivity for lime-only mortar. When a soft, self-healing, porous, and breathable surface is desired, then a high-calcium, “softburned” lime is ideal. Only a purpose-made architectural lime putty will have high surface area (greater than 30 m2/g) and porosity that comes from “soft burning” and the chemical purity of a consistently high calcium content. Together these characteristics ensure all of the lime is acting as a binder (cementing the aggregate particles). Architectural lime putty makes great mortar without Portland cement or pozzolans. And only lime mortars are consistently compatible with historic lime-only mortars that rarely exceed 200 p.s.i. and allow full water and vapor movement to the exterior of a wall. Remember, the role of mortar is to cushion the masonry units and accommodate movement while eliminating point-loading. Lime mortars meet this requirement fully. The lime cycle is a closed loop. Calcium Carbonate [CaCO3, i.e. limestone, oyster shell] is fired to drive off the CO2, making Calcium Oxide [CaO, quicklime]. When water is introduced during the volatile process called slaking, calcium hydroxide is formed [Ca(OH)2]. Lime putty is calcium hydroxide. As water leaves the lime, carbon dioxide from the air begins to take its place, once again reacting with the lime to create Calcium Carbonate again. There is an increase in mass associated with carbonation that counteracts shrinkage from water loss. What if we slake calcium oxide ourselves? Good quality control in manufacturing Sample A produced an optimum lime putty. The same oxide slaked by hand without precise control of water feed rate and temperature created the inferior putties, C and D. Reactivity is created through careful control in firing and slaking. Small particles and high surface area create longer decantation times (the time necessary for a particle to settle out). Viscosity is related to surface area and plasticity. Greater plasticity and water-holding capacity mean better working properties and contribute to low shrinkage from water loss. True lime mortars set (carbonate or “cure”) by reacting with atmospheric CO2, creating a sort of man-made limestone. Hydraulic mortars (Portland cement, bagged mortar mixes, and hydraulic limes and cements) set by reacting with water. The firing of all mortar constituents drives off CO2, but the reabsorption of this CO2 by lime mortars makes it a more environmentally-responsible building choice. Lime mortars are also less fuel intensive to produce than Portland-based mortars. Blog post attributed to www.preservationscience.com ...read more
By Lancaster Lime Works January 28, 2015
Concrete was traditionally considered for outdoor functioning, such as sidewalks. When used indoors, concrete used to be thought of as simply a foundation. Concrete slabs in homes are usually covered with carpet, tile, or linoleum. This is changing, however, with concrete resurfacing. ...read more
Should you be looking to create a floor for your shower you will need to mix the cement that will act as your shower’s base. This will need to be done regardless of whether you plan on leaving the floor bare or installing tile. ...read more