<h3><span style="color:#2c3e50">THE TYPICAL</span>&nbsp;<span style="color:#e74c3c">FORMULATION OF GRC</span></h3>

<table border="1" style="width:100%">
	<tbody>
		<tr>
			<td>Cement</td>
			<td>50 kg</td>
			<td>50 kg</td>
		</tr>
		<tr>
			<td>Fine aggregate</td>
			<td>50 kg</td>
			<td>50 kg</td>
		</tr>
		<tr>
			<td>Glass fibre</td>
			<td>4.5-5%</td>
			<td>2-3.5%</td>
		</tr>
		<tr>
			<td>Plasticiser</td>
			<td>0.5 kg</td>
			<td>0.5 kg</td>
		</tr>
		<tr>
			<td>Polymer</td>
			<td>5 kg</td>
			<td>5 kg</td>
		</tr>
		<tr>
			<td>Water</td>
			<td>13.5 litre</td>
			<td>14.5 litre</td>
		</tr>
	</tbody>
</table>

<p>&nbsp;</p>

<h3>THE SPECIFICATION&nbsp;<span style="color:#e74c3c">OF GRC</span></h3>

<p>Unlike traditional concrete, which is classified by its compressive strength, GRC is classified by its flexural strength or Modulus of Rupture (MOR). GRC is categorised into three grades, Grade 8, Grade 10 and Grade 18, with each grade identified by its corresponding MOR value .Over the last 50 years, GRC best practice standards have been developed and applied across Europe, America, Asia and Australasia that set the benchmark for producing high quality GRC. For more detailed information about the production standards for GRC products, refer to the International Glass Reinforced Concrete Association, &quot;Specification for the manufacture, curing and testing of GRC products, Third Edition - March 2010&quot;.</p>

<ul>
</ul>

<h3>THE TYPICAL STRENGTH PROPERTIES OF GRC&nbsp;<span style="color:#e74c3c">AT 28 DAYS AFTER MANUFACTURE</span></h3>

<table border="1" style="width:100%">
	<tbody>
		<tr>
			<td>Ultimate strength (MOR) MPa</td>
			<td>20-30</td>
			<td>10-14</td>
		</tr>
		<tr>
			<td>Elastic limit (LO R) MPa</td>
			<td>7-11</td>
			<td>5-8</td>
		</tr>
		<tr>
			<td>Interlaminar strength MPa</td>
			<td>3-5</td>
			<td>NA</td>
		</tr>
		<tr>
			<td>In-planar strength MPa</td>
			<td>8-11</td>
			<td>4-7</td>
		</tr>
		<tr>
			<td>Compressive strength MPa</td>
			<td>50-80</td>
			<td>40-60</td>
		</tr>
		<tr>
			<td>Impact strength Kj/m2</td>
			<td>10-25</td>
			<td>10-15</td>
		</tr>
		<tr>
			<td>Elastic modulus GPa</td>
			<td>10-20</td>
			<td>10-10</td>
		</tr>
		<tr>
			<td>Strain to failure %</td>
			<td>0.6-1.2</td>
			<td>0.1-0.2</td>
		</tr>
		<tr>
			<td>Dry density t/m3</td>
			<td>1.9-2.1</td>
			<td>1.8-2.0</td>
		</tr>
	</tbody>
</table>

<p>&nbsp;</p>

<p>GRC is typically manufactured by &#39;Spray&#39; or &#39;Premix&#39; production techniques. The choice of production technique is determined by the specific project requirements and depends on factors such as strength, size, specifications, etc. Sprayed panels can be constructed with a larger glass fibre content (5-6%) than premixed structures (2-3%) creating a stronger material. While premixed GRC is generally not as strong as sprayed GRC, the production technique is easily automated and can be a quicker way to create smaller structures.</p>

<ul>
</ul>

<h3>SP<span style="color:#e74c3c">RAY</span></h3>

<p>The &#39;Spray&#39; production technique involves spraying layers of mix into fibreglass or rubber moulds. The first layer is a cement/aggregate mix that forms the surface and subsequent layers contain chopped glass fibres. The spray gun contains both the grout nozzle and glass chopping gun so that the grout and glass fibres are sprayed simultaneously. Each layer is compacted with rollers to create the required thickness, typically 10-15mm.It takes 2-4 hours to produce the GRC unit and the unit is then left in the mould for an additional 18 hours. Polythene and a polymer curing compound are used to prevent moisture loss before the unit is exposed to the elements. The unit can be fixed with stiffening ribs or support restraints.</p>

<ul>
</ul>

<h3>PRE<span style="color:#e74c3c">MIX</span></h3>

<p>The &#39;Premix&#39; production technique involves pouring or pumping a cement/fibre mix into a mould, similar to other precast production processes. The mix is compacted using vibration or by adding other components to the mix. The unit is left in the mould to set and is demoulded the following day. As with the &#39;Spray&#39; method, polythene and a polymer curing compound are used to maintain moisture within the unit before it is exposed to the elements. For the typical formulation of spray or premix GRC components, click here for Technical Information.</p>

<ul>
</ul>

<p><img src="http://localhost/creative/html/creative-frc/premix.jpg" /></p>
